Agrodok 36

Preparation of dairy
products

Pauline Ebing
Karin Rutgers

This publication is sponsored by: ICCO, Interchurch organisation for development cooperation© Agromisa Foundation and CTA, Wageningen, 2006.
All rights reserved. No part of this book may be reproduced in any form, by print, photocopy,
microfilm or any other means, without written permission from the publisher.
First English edition: 1985
Sixth revised edition: 2006
Authors: Pauline Ebing, Karin Rutgers
Editor: Tineke van der Haven
Illustrator: Bertha Valois
Design: Eva Kok
Translation: W.J. Guijt (revision: Catharina de Kat-Reynen)
Printed by: Digigrafi, Wageningen, the Netherlands
ISBN Agromisa: 90-8573-062-7
ISBN CTA: 978-92-9081-341-5

Foreword
This Agrodok is meant to serve as a manual for those who want tostart small-scale production of dairy products in developing countries.
The booklet introduces the reader to small-scale dairy production
using simple techniques. It also gives an idea of the opportunities
available to earn some income through cheese making. Locally there
is often much knowledge available on production of dairy products.
We would advise you to get acquainted with such methods in yourarea before starting on your own. We would also suggest that you not
introduce Western dairy products if there is no need to do so,
especially if local dairy products are already being made.
The authors have used information provided by the late J.C.T. van den
Berg of the Wageningen Agricultural University in the Netherlands,
who had much experience with factory production of dairy products inthe tropics. The recipes described in this Agrodok have been drawn
from various sources. We would greatly appreciate it if you would
write to us about your experiences with the recipes in this book andwith information on other local recipes. Where possible, they will be
included in a future revised edition.
The sixth, revised edition has been updated with some technologicalknowledge about dairy science and dairying techniques andexperience in extension service. However it is utterly impossible tocover the whole field of dairy technology. To do this, one needs basic
knowledge of dairy chemistry, physics and microbiology, in addition
to hygiene and handling of the milk on farm level. Therefore thisbooklet has to be considered as an introduction. Interested readers
have to extend their knowledge by means of further reading andprofessional training in some important dairy techniques. The list ofliterature references and useful addresses may be of help.
Tineke van der Haven
Wageningen, August 2006

Foreword

3

Contents
1
1.1
1.2
1.3

Introduction
What is this booklet about?
Why process milk?
What problems can arise?

2
2.1
2.2
2.3
2.4
2.5

Significance of milk and dairy products for humans 10
Milk as food
10
Composition and characteristics of various types of milk 12
Infant nutrition13
Lactose intolerance
15
Milk and dairy products in the diet
16

3
3.1
3.2
3.3

HygieneDeterioration due to micro-organisms
Contamination of milk with extraneous matter
Hygienic production, storage and processing of milk

18
18
22
22

4
4.1
4.2
4.3
4.4

Processing techniques
Pasteurisation
CoolingSouring by fermentation or acidification
Creaming

28
29
31
33
33

5
5.1
5.2
5.3
5.4
5.5

Starter cultures
The development of lactic acid bacteria
Cultivation of starter cultures of lactic acid bacteria
Growth of starter cultures
Maintenance of starter cultures
Preparing your own culture

35
35
36
37
40
41

6
6.1
6.2

RecipesCreamSour cream

44
45
46

4

Preparation of dairy products

6
6
6
8

6.3
6.4
6.5
6.6
6.7
6.8
6.9

ButterButtermilk and sour milk
Ghee
Koa
Rabi
Yoghurt
Kefir

46
50
51
52
52
53
55

7
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8

CheeseUtensils for making cheese
The quality of milk used to make cheese
Coagulation of the milk
Separating curd and whey
The use of cheese whey
Collection and preservation of the curd
Maturation of the cheese
Cheese recipes

59
62
64
64
67
68
69
71
73

Further reading

82

Useful addresses

83

Appendix 1: Measures

86

Contents

5

1

Introduction

1.1

What is this booklet about?

Livestock is usually kept for various reasons in the tropics such as
traction, the provision of meat, wool, hair, skins and manure which,when dried, can be used as fuel. Milk is often no more than a byproduct of animal husbandry, although it is a valuable foodstuff.
Furthermore, keeping livestock can be a way of saving. In the event ofan emergency, animals can be sold to provide money. As such, animalhusbandry is also a kind of insurance against, for example, disease andcrop failure.
It is not by accident that a certain kind of milk-producing animal is
kept in a specific area. This is due to climatic conditions, locallyprevalent diseases, available fodder, the possibilities for the owner totake risks, additional tasks that the animal is expected to do, religion
and tradition and the preference for products that the animal produces.
Keeping dairy animals often leads to a surplus of milk. If milk
production is higher than consumption in a certain area, the surplus
can either be sold on the market, or it can be processed so that it does
not go off. If the quantity of milk to be processed is small (up to 100
litres at a time), this activity is considered to be small scale. This
Agrodok deals with the small-scale processing of milk using simple
equipment.

1.2

Why process milk?

There are many reasons to process milk into dairy products, such as
the following:? Many dairy products can be kept longer than fresh milk, therefore
the milk does not have to be consumed immediately.
? The demand for fresh milk may be limited, and there may be moreinterest in dairy products.

6

Preparation of dairy products

? If the daily amount of fresh milk for sale is limited, it may be more
economical to process the milk into less perishable products, store
them, and sell them later in greater quantities.
? There may be no market for fresh milk close by, and only preserved
products can be sold at markets at a greater distance.
? Greater financial gain may be obtained.
Apart from these reasons, it should also be realised that many
population groups in Asia and Africa cannot or can hardly consume
milk because of so-called lactose intolerance. Lactose intolerance
implies that the body is almost or entirely unable to digest the milksugar, lactose, which is found in milk. Only small amounts of milk (upto 200 ml) consumed several times a day can be digested. Dairy
products in which a proportion of the milk sugar is converted during
production, such as cheese, curd, yoghurt and sour milk or buttermilk,
do not cause many problems in this respect.

Figure 1: Milk products

Introduction7

Before processing surplus milk, one must consider whether it isprofitable to do so. The processing is not always easy and there may
be losses. For example, a waste product of cheese making is whey,
which contains many valuable nutrients. If the whey is not used, avaluable part of the milk is lost. Furthermore, while milk is being
processed quality deterioration may occur and it can go off. Only
when milk is drunk immediately can you be sure that nothing is lost.

1.3

What problems can arise?

Small-scale processing of milk means the processing of small
quantities of milk, up to 100 litres at a time, using simple implements
and as little extra equipment as possible. Processing milk in the tropics
can be difficult because of the high temperatures and high relative
humidity often found there. These conditions present special problems
in choosing the right kind of dairy products. Their storage life must
always be taken into account.
High temperatures are bad for cheese making, especially for maturingcheeses. High temperatures also cause the bacteria already present inmilk to multiply quickly. Milk sugar then turns sour, leading to thecurdling of milk. However, these lactic acid bacteria are not harmful
to humans.
Thorough cleaning of dairy utensils and equipment is essential.
Anyone handling milk must also pay great attention to hygiene. Lackof hygiene can contaminate milk with other types of bacteria, which
turn it sour and reduce its storage life. The prevention ofcontamination is especially difficult when milk is collected fromvarious places and processed centrally. Addition of even a small
quantity of infected milk contaminates the total quantity of the milk.
A further problem is the lack of equipment. One has to try to manage
with simple dairy equipment, but even this can be difficult to find forsmall-scale milk processing. Electricity is usually not available soelectric equipment (e.g. for cooling) cannot be used unless a generator

8

Preparation of dairy products

is installed. Additives such as rennet for cheese making are often
difficult to obtain in the tropics.
The following chapters discuss the importance of milk in the diet,hygiene and milk processing techniques.
The second part of the booklet gives guidelines for heating, coolingand fermentation and for the processing of cream, butter, ghee, sour
dairy products and cheese.

Figure 2: Sheep provide milk, meat, wool, skin, pelts and manure

Introduction

9

2

Significance of milk and dairy
products for humans

2.1

Milk as foodMilk contains components thatare essential to humans such asproteins, carbohydrates, fat,water, all the B-vitamins,
vitamins A and D, calcium andphosphorus. It also provides
energy.
An important protein in milk iscasein (in many cases 80% of
the milk protein). This is the Figure 3: Main components of milkbase for cheese making. Casein
is linked to calcium phosphate, which is why milk contains a
relatively large amount of this salt that is a very important nutrient forhumans and animals.
In addition to casein, milk contains whey proteins (20% of the milk
protein). The whey proteins are in most cases not incorporated in thecheese; they remain in the whey. Whey proteins (globulins andalbumins) have a very high nutritive value.
Milk protein is of a high quality. This means that the human body canuse a large part of the protein efficiently. Proteins in various otherfoodstuffs have a complementary effect. In combination with cereals,
potatoes, meat, eggs or nuts in one meal, the body can use an evengreater percentage of the milk protein.
Apart from milk, there are other animal protein sources such as fishand meat. Vegetable protein, which is also important in making the
body's proteins, is found in cereals and pulses. Protein is needed by

10

Preparation of dairy products

the body for growth, replacement of worn-out body proteins and the
production of compounds that the body needs.
Milk sugar (lactose) is a carbohydrate, a necessary component to keep
the body going. Our bodies burn carbohydrates in the same way anoven burns wood. Through this combustion, energy is released which
is used by our bodies for many kinds of activities.
Milk fat is present in the form of small fat globules, which have alower weight than the other components of the milk. When cow milk
is allowed to stand, these globules collect on top of the milk and forma layer of cream. Buffalo milk also forms some cream on top, butother kinds of milk, such as that of sheep and goats, hardly form alayer of fat at all. For these types of milk one needs to separate thecream from the milk. Milk fat is easy to digest. The body uses fat as afuel or stores it as fat reserves.
Milk is also an important source of minerals and vitamins. It contains
large quantities of calcium, which can easily be absorbed by the bodyafter digestion and is important for the formation of bones (theskeleton). Milk is also an important source of vitamin B2 (Riboflavin),but there is little vitamin C in milk. Therefore a person's diet must also
include vegetables and fruits in order to ensure a sufficient supply ofvitamin C.
Milk is able to compensate for a lack of certain nutrients in amonotonous diet because of the great diversity of nutrients it contains
and the high value of milk protein. It can therefore greatly improve thequality of the diet. Products derived from milk contain these nutrientsto a greater or lesser extent. Milk is especially desirable for vulnerable
groups, for instance babies, toddlers, children and pregnant andnursing mothers. Always strive for a healthy, varied diet, which apartfrom milk also includes cereals, pulses, vegetables, fruits and if
possible meat or fish.

Significance of milk and dairy products for humans

11The various types of milk differ in various ways, including nutritional
value. In the next pages this is dealt with in more detail.

2.2

Composition and characteristics of various
types of milk

The composition of mother's milk and milk from cow, buffalo, goat,
sheep, camel, donkey and lama is shown in table 1. The figures intable 1 show that the composition of the milk of non-ruminants, e.g.
mother’s milk and mare milk, differs distinctly from the milk of
ruminants (cow, goat, sheep, etc.). This may be partly explained bydifferences in the digestive system of the two groups.
Apart from the differences in cream formation there are other
differences between the various kinds of milk. There is a lot of provitamin A (carotene) in cow milk, giving it its yellow colour, but notin buffalo, goat or sheep milk. In the milk of goats and sheep the
carotenoids are already converted into the colourless vitamin A. This
is why only cow milk is yellow in colour.
Table 1: Composition of various types of milk (source: FAO
Nutritional Studies 27)
Milk source
Human(mother’s) milk
Friesian cow
Guernsey cow
Indian buffalo
Goat
Sheep
Mare
Donkey
Camel
Lama

12

fat (%)

protein (%)

lactose (%)

calcium (%)

energy(cal/100g)

4.6

1.2

7.0

0.0

73

3.5
4.7
7.5
4.5
7.5
1.6
1.5
4.2
3.2

3.3
3.2
3.8
3.3
5.6
2.2
2.1
3.7
3.9

4.6
4.7
4.9
4.4
4.4
6.0
6.2
4.1
5.3

0.1
0.1
0.2
0.1
0.2
0.1
0.1
?
?

62
75
100
71
105
47
46
70
65

Preparation of dairy productsBuffalo milk curdles sooner than cow milk. Unless the preparation isadjusted, cheese made from buffalo milk will mature more slowly andhave a drier consistency than cheese made from cow milk. Goat milk
can have an unpleasant smell; this can be prevented by boiling themilk as soon as possible after milking. Between some goats or breedsof goats there may be a difference in the taste of the milk.
Cow milk accounts for 91% of the world's milk production. Buffalo,goat and sheep milk account for 5.9%, 1.6% and 1.7% respectively.
Although there are enormous regional differences we can generally
say that, if it is to be drunk, milk from cows or buffaloes is preferredto that from goats and sheep. This is because of the more neutral
flavour of cow milk and buffalo milk.
Goat and sheep milk are, just like the milk of cows and buffaloes,
popular for making cheese and soured milk products (especially sheepmilk). Camel milk is usually drunk. Mother’s milk is the most ideal
food for a suckling infant. Nonetheless, many substitutes have beendeveloped which find a ready demand. We shall pay more attention to
infant nutrition in the next section.

2.3

Infant nutrition

Mother’s milk is best suited to the needs of a baby, and contains
certain components that protect an infant against infectious diseases.
All the nutrients a baby needs, except iron and vitamin C, are to befound in sufficient quantities in mother’s milk. At birth, a baby has astore of iron in its liver, which it uses up during its first 6 months. Anykind of supplementary feeding is only necessary after 3 months, as themother's milk then no longer supplies all the nutrients the infant needs.
Fruit juice and mashed fruit provide additional vitamin C, which theinfant then needs. Supplementary feeding of energy-giving foods isalso desirable. Mixing small quantities of milk powder into mashedfood can considerably improve the food's value (especially the valueof its protein).

Significance of milk and dairy products for humans13

It is advisable to continue breastfeeding as long as possible because
mother's milk is often the only source of animal protein for a baby. If
the mother cannot breastfeed, does not have enough milk or dies,bottle feeding is a solution and the best substitute. However, inpractice often too much water is added to the (artificial) baby food,
which is usually bought in powder form. It becomes too watery and istherefore not nutritious enough. Moreover, artificial foods are costly
and require good hygiene. Dilution with water is often a cause of
infection because the available water may be polluted. Water used forbottle feeding must first be boiled, but sterilising water by boiling uses
a lot of fuel, which is often in short supply. By using a cup or a spoon
it is easier to maintain the necessary hygiene rather than a bottle
because they are easier to clean.

Figure 4: Breastfeeding is the healthiest and most hygienic way tofeed a baby

Money might be better spent on essential necessities of life than on
artificial infant food if the latter is not strictly necessary. If a baby
cannot digest milk, you will be forced to use milk products, which do
not contain lactose. This is the case with inherited lactose intolerance.
We shall discuss this in more detail.

14

Preparation of dairy products

2.4

Lactose intolerance

Lactose intolerance means that the human body is almost, or entirely,
unable to digest the milk sugar, lactose, which is present in milk
because the body lacks the enzyme lactase. Lactase splits the lactose
into glucose and galactose. The latter two mono-saccharides can easily
be absorbed in the intestine.
Undigested lactose can be converted by the microbial flora in theintestine into lactic acid and gases. Consumption of larger quantities
of milk thus causes flatulence, stomach cramps and diarrhoea.
‘Lactose intolerance’ is thus often called ‘lactase deficiency’.
There are different forms of lactose intolerance among children:? Congenital lactose intolerance. In this case, a baby cannot digest
milk because the baby lacks the enzyme lactase, necessary for the
breakdown of lactose into glucose and galactose.
? Lactose intolerance among children who are 2-5 years old. From theage of two years lactase activity in a child decreases and the child
may have problems due to insufficient lactase by the time he or she
is 4-5 years old. Consumption of small quantities of milk (one glassat a time) usually does not cause any problem. It is also possible toprevent problems by eating fermented milk products, in which partof the milk sugar has been converted, such as cheese, yoghurt andbuttermilk.
? Lactose intolerance as a result of intestinal disease and/or
malnutrition, especially in babies and toddlers. The lactose activity
is temporarily decreased making it necessary to use lactose-freemilk products for a short time. Cheese and fermented products likeyoghurt, in which milk sugar has been converted, are also suitable.
Apart from lactose intolerance, the use of milk also depends on otherfactors, which we will now discuss.

Significance of milk and dairy products for humans

15

2.5

Milk and dairy products in the diet

Diet refers to the way people feed themselves and the foodstuffs they
use to do so. This is strongly influenced by people’s traditions andreligion, their economic position, their place in society and thepossibilities offered by their natural surroundings. It is not surprisingthat each population group has its own diet. The use of milk and dairy
products can also be looked at when examining the diet.
Here are a few examples of how the factors mentioned above can
influence the role and form of milk and dairy products in the diet.
? The cow is a sacred animal in India; therefore the rennet used incheese making may not be taken from a calf's stomach.
? If milk or dairy products have to be bought, money is needed.
? In densely populated areas, people are forced to use all available
land for crops that give a maximum yield, or crops that can bedirectly consumed by the people. This limits the land available fordairy farming.
? It may not be possible to keep cattle in certain regions, e.g. thehumid tropics, due to the natural environment. For example, inhumid areas of West Africa cattle cannot be kept because they are
the host of the tsetse fly, which transmits sleeping sickness.
For these reasons, milk and dairy products in the diet can be of greateror lesser importance in one area or another. Economic and social
situations are especially subject to change and dietary patterns changewith them.
New foodstuffs may be introduced to (partly) substitute others.
Adoption of new products is often no easy matter; sometimes
centuries-old traditions may have to change. Also, taste and othercharacteristics such as texture are important in the acceptance of new
kinds of food. Something that may be considered very tasty in one
place, may not be appreciated elsewhere.

16

Preparation of dairy products

Figure 5: Camel milk is a very popular food in parts of Africa andthe Middle east

Significance of milk and dairy products for humans17

3

HygieneMilk should be handled with care. There are several factors that canmake milk go off and become unsuitable for further consumption.
These include:? the presence of too many micro-organisms in the milk
? contamination by diseased animals (tuberculosis, brucellosis) and/or
people? bacterial and/or chemical conversion of certain substances in themilk? contamination of the milk with antibiotics (used for treatment ofdiseased animals), disinfectants, pesticides and so on.
The above-mentioned factors always cause some deterioration of milk.
In some cases it is only the flavour that is affected, but usually the
structure and smell of milk also change. In the case of contamination
with antibiotics and disinfectants, the milk’s appearance does notchange, but fermentation, which is necessary for processing the milk,
is inhibited.
We will first discuss the way micro-organisms cause the deteriorationof milk. Then precautions which can be taken to minimise the impactof these factors will be explained, and some suggestions for cleaningand disinfection will be given.

3.1

Deterioration due to micro-organisms

Bacteria, yeasts and moulds are all called: micro-organisms.
Micro-organisms are very small and cannot be seen with the naked
eye. They are found everywhere in nature: in the air, water, and soil
and also in food and milk. Micro-organisms can multiply very rapidly.
Milk in the udder of a healthy animal contains almost no microorganisms (aside from lactic acid bacteria). After the milk leaves the18

Preparation of dairy productsudder contamination with, sometimes harmful, micro-organisms willtake place during milking, milk handling, transport and storage. Milk
may be contaminated with micro-organisms originating from the skinof the animal, the milker’s hands, the milking utensils or the air.
Most micro-organisms are not harmful, but some can cause diseases
like salmonella infection, dysentery, tuberculosis (in man and inanimals), diphtheria and typhoid. These disease-causing microorganisms are called pathogenic bacteria. Through inadequate
hygiene, diseases can be transmitted from person or animal to person.

Figure 6: Diverse sources of contamination: a shows badly
cleaned utensils contaminating milk; b improper milking is also asource of contamination; c shows multiplication of micro-organisms
during storage; d heating kills the micro-organisms.

Micro-organisms can multiply very rapidly in milk. Temperature plays
an important role in the life of micro-organisms. Their growth canstart at a temperature of about 4°C. It is therefore very important toHygiene19

store milk or milk products at a temperature no higher than 4°C;
otherwise deterioration will take place rapidly. Above 20°C, bacteria
multiply at an incredible speed.

Figure 7: Temperature and deterioration

Most micro-organisms are killed during pasteurisation, e.g. at atemperature above 63°C for a period of at least 30 minutes. But a few,
the so-called spore-forming bacteria, will survive more intense
heating. They can give problems like off flavours and coagulation inpasteurised milk.
Yeasts and moulds
Yeasts are micro-organisms that can ferment sugars into alcohol, gas
and other substances. They are about 5-10 times larger than bacteria.
Reproduction usually takes place through budding. Yeasts usuallygrow in an acid environment; they need oxygen and they canwithstand rather high concentrations of acids.

In dairy products, yeasts are usually found in soured products like sour
milk or buttermilk, sour whey, butter, and curd and on the surface ofcheese. When present in large numbers, they produce gas and theycause undesirable off flavours of the product.
Moulds are string-like micro-organisms. The fine threads, called
mycelium, are large enough to be seen with the naked eye. To develop
they need atmospheric oxygen, and they thrive best in humid and acidconditions. Moulds multiply by forming spores. These float easily
through the air and can often be found on poorly maintained ceilings

20

Preparation of dairy products

and walls. Their mobility makes them an important source of
infection.
Moulds can be seen on the surface of butter or cheese in the form ofcoloured spots. For some soft cheeses (like Camembert and Brie)
moulds are essential for ripening. In general, moulds are harmless, butsome produce poisonous toxins (mycotoxins), such as aflatoxin in
peanut products.
Cells and spores of moulds and yeasts are destroyed by pasteurisation(heating the milk 30 minutes at 63°C or 20 seconds at 72°C).
Bacteria
Bacteria are single-cell micro-organisms that multiply by cell division.
Raw milk and many dairy products contain many different kinds ofbacteria. Environmental conditions (such as acidity, temperature,humidity or amount of oxygen) can change, making conditions lessattractive for one group of bacteria but at the same time creating
optimal conditions for another type. This is why some families ofbacteria will always be found in milk or dairy products (lactic acidbacteria).

An exception must be noted, which is dried products like milk
powder. Micro-organisms cannot grow without water and therefore thenumber of bacteria in uncontaminated milk powder will be low.
Bacteria found in milk can be divided into two groups: useful andharmful. Lactic acid bacteria (e.g. Streptococcus lactis) are useful.
They produce lactic acid, which is not harmful and gives milk a fresh,sour taste. Moreover lactic acid is a good preservative for the sour
products. Pathogenic bacteria (those that cause diseases in humans)cannot grow in acid products. When producing certain dairy products
like soured milk, yoghurt and cheese, good use is made of these
specific properties (see chapter 5).

Hygiene21

Sometimes milk is spoiled by the growth of bacteria that do not
produce lactic acid. In this case, certain disease-causing bacteria candevelop and whey separates from the milk. This usually happens after
long storage of pasteurised milk. The smell is unpleasant and the taste
bitter. Such milk should not be consumed.

3.2

Contamination of milk with extraneous
matterExtraneous substances must be prevented from entering into the milk.
These can be dangerous to one’s health or cause unpleasant flavours
and smells, reducing the suitability of milk for further processing.
Some examples are cleaning and disinfecting agents, medicine,pesticides and pieces of metal or glass. The feed given to animals,
such as some weeds, onions and cabbage, can also influence the tasteof the milk. This can be avoided by feeding the animals after milking.
Good hygiene can reduce deterioration. How to achieve a good levelof hygiene will be discussed in the following pages.

3.3

Hygienic production, storage andprocessing of milk

Contamination occurs when micro-organisms enter into the milk.
Possible sources of contamination during production, storage andprocessing are:? inflammation of the udder (mastitis)? the animal itself: skin of teats and udder? conditions at the milking place (floor, dung, dust, dirty water, etc.)? the person milking? utensils and equipment used during processing? the air and environment
It is no easy task to keep micro-organisms out of milk. Much depends
on the person who is milking, the care taken of the animals and thecleanliness of the utensils. If everything is well sanitised and kept
clean, relatively few micro-organisms will enter into the milk. Good

22

Preparation of dairy products

hygiene is of major importance. In addition, milk - if not used orprocessed immediately - should be cooled after milking and kept cool.
Good hygiene measures therefore:? Prevent contamination of the milk.
? Prevent bacterial growth through good refrigeration of the milk.
Hygiene during milking
There are several possible causes of contamination during milking.

In a normal, healthy cow very low numbers of bacteria are foundinside the udder and the teats. Cows possess various mechanisms toprevent the entry of bacteria. To avoid problems while milking, it isimportant that an animal become accustomed to the activity. It willthen know that it will be milked, and will react positively to it. Such
positive behaviour can start if, for instance, it hears milk cansclanging, feels its udder being cleaned, etc. Then the animal is easier
to milk and gives more milk. Stress and unrest make the cows move
too much and kick; consequently more dirt and manure can enter into
the milk.
When a cow has an udder infection (mastitis), its milk will becontaminated with the bacteria that cause the udder infection, and thatmay produce pus and sometimes blood. Milk from these animals
should not be used in any way. Mastitis can be prevented bymaintaining good hygiene and avoiding injury to the teats during
milking. An infected udder is not always easy to see. When an udder
infection occurs, it is advisable to remove milk from the udder veryfrequently (e.g. every 3 hours by hand). The number of microorganisms in the udder is thus reduced. Be aware, however, thatmilking an infected udder by machine or by hand is often painful forthe animal. The animal will kick frequently and this can be an
important source of contamination of healthy cows.
Bacteria can be transferred from the skin or teats to the milk, evenwith healthy dairy cattle. It is therefore important to clean the udder

Hygiene23

before milking. Wipe the udder clean with a dry, clean, preferably
disposable cloth to prevent infection. If the teats or udder are reallydirty, they must first be washed with clean, hand-warm water and aclean cloth and then dried with a clean towel. Cleaning the udder
improves the cleanliness of the milk and makes milking easier. Skinand hair can also be sources of infection.
Do not feed animals first before milking, it may create a lot of dust.
See to it that the floor is clean, and be careful when clearing dung,
mud or dust. A clean, well-illuminated milking place and fresh
surrounding air are essential to maintaining good hygiene. Insects
such as flies and cockroaches can also be sources of infection. Try tocontrol them as they can carry many bacteria and viruses.
When milking, the milk is caught in a pail or bucket. Dirty milking
equipment is the main source of infection of milk.
If residues of milk remain in the equipment because of impropercleaning and drying, bacteria will develop in these residues. Thesebacteria are already accustomed to the milk and will multiply rather
quickly during transport and storage of milk in the equipment. Usepails and buckets that are smooth on the inside, for instance seamlessmetal buckets.
All milking equipment should be thoroughly cleaned immediately
after each use. Use soap or other detergents if necessary. Make surethat the water used is clean. If you are in doubt, boil it for several
minutes or add chlorine. Very important: after cleaning, the equipment
should be stored upside down in such a way that the inside of thebuckets and cans dry. This prevents the remaining bacteria fromgrowing.
The person milking plays the most important part in maintaining
proper hygiene during production. He or she keeps an eye on thecondition of the animal, chooses the milking place and cleans all theequipment. He or she should have clean hands and wear clean clothes.

24

Preparation of dairy products

If the milker suffers from tuberculosis, salmonella infection, dysentery
or some other disease, the risk of contamination of the milk becomesvery high; it would be wise to have somebody else take over. This isalso the case if the milker has open wounds or ulcers.
Hygiene during storage and processing
By now you should know that milk should be processed as quickly as
possible after milking and that it should be properly stored in order tominimise its chances of spoiling.

It is best to filter fresh milk through a filter or clean cloth. This willremove visible dirt that might have entered into the milk. Clean or
replace the cloth during filtering or filter the milk several times. The
cloth should be thoroughly cleaned after use and then left to dry in thesun.
In tropical conditions, raw milk, i.e. non-pasteurised milk, goes off
within a few hours. It must therefore be kept cool and quickly
pasteurised and again cooled to a temperature of 4°C if possible.
Properly pasteurised and cooled milk can be kept for a few days, evenin a warm climate.
If you are not able to cool milk below 10°C, then do not mix different
batches. Even if the older milk is still good, you will end up with anincrease in bacterial growth and reduction of the overall quality. Useclean equipment for storage. Containers that are clear, such as glass,should be stored in the dark as light reduces the quality of milk. Clean
your equipment with clean water.
Cleaning and disinfection
Utensils must be cleaned in such a way that all dirt, food residues,
feed and micro-organisms are removed from the surface of theequipment. Dirty saucepans, jugs, milking equipment and utensils
should be cleaned immediately after use. Washing soda (sodium
carbonate) dissolved in hot water is an excellent cleaning agent. It
may be useful to disinfect equipment in order to kill any remaining

Hygiene25

harmful micro-organisms. You can use a chloride solution such as
bleach (sodium hypochlorite).

Figure 8: Cleaning utensils

A proper way of cleaning your equipment is the following:? Start cleaning immediately after milking, so that milk residues will
not dry and stick on the buckets and utensils.
? Rinse well with water.
? Scrub the tools in a hot soda solution (1.5 tablespoons of soda to 5
litres of water), using a small amount of water to dissolve the soda
before adding it to the rest of the water.
? Rinse well with hot water.
? Buckets, tubs, etc., should be turned upside down on a rack duringstorage; the water can then drain and no dirt or dust can enter. Let
the utensils dry to prevent bacterial growth.

26

Preparation of dairy products

Well-cleaned tools are nearly sterile, only a small part of the bacteria
remains on the tools. If these tools dry during storage hardly any
bacteria will be present. In that case disinfection is not necessary.
Tools which are used for storage of pasteurised milk or for cheese
making and which do not get a heat treatment together with the milk
can be disinfected after cleaning or before use. Proceed as follows:? Clean all your equipment properly. The following step will beineffective if the utensils are not clean to start with.
? Disinfect in a chloride or bleach solution after cleaning or shortly
before use. Add 2 tablespoons of bleach per 4.5 litres of water.
It is advisable to use stainless steel equipment, cheesecloth andwooden utensils. Tools or any other equipment made from aluminium
should not be washed in a strong soda solution, as soda attacks
aluminium. Iron utensils will rust in a strong chloride solution.
Therefore rinse and dry these utensils immediately after cleaning anddisinfection.
If you have no cleaning agents -like soda- or disinfectants, you candisinfect your equipment as follows:? Thoroughly clean the utensils using clean water.
? Rinse with a soap solution.
? Dry the equipment on a rack in the sun upside down or rinse withboiling water.
WARNING: Take care that acid cleaning agents (e.g. nitric acid) and chlorine
never come in contact with each other as very poisonous fumes can beformed.
Cleaning agents and disinfectants are chemicals that - if not diluted - canirritate the skin. Direct contact should therefore be avoided; wear gloves, if
possible. Do not use any disinfectants other than chloride (bleach). As
cleaning agents and disinfectants are dangerous products, they should belocked away in a safe place, where no unauthorised person can get at them.
Label the bottles clearly.

Hygiene27

4

Processing techniques

Milk can be stored longer if it has been processed. Extended storage ispossible if you are able to control the growth of micro-organisms. The
processing technique used will determine the storage life of the milk
and dairy products. The following rules should be followed during the
production, storage and processing of milk.
? Always wash your hands and avoid putting them in the milk if notnecessary.
? See to it that all equipment used during processing is properly
cleaned and disinfected if needed.
? Take care that no dirt particles or insects enter into the milk.
? Try to prevent the use of copper utensils. (Copper can give off
flavours in butter and milk.)? Do not expose milk to sunlight; store it in a dark place.
? The use of a thermometer is recommended.
? Make sure that milk used for consumption has always been boiled
or pasteurised.
? Never store raw (i.e. unheated) milk if it is not immediately cooled
below 4°C.
? Never drink raw milk because it may contain pathogenic bacteria
like tubercular bacteria and salmonella.
The following processing techniques will be dealt with in this chapter:? pasteurisation? cooling? souring (acidification)? creaming.
Heating and cooling are in fact ways to preserve milk, but for
convenience we will deal with them under the heading of processing
techniques.

28

Preparation of dairy products

4.1

Pasteurisation

As you by now know, milk contains certain micro-organisms that can
spoil it. These bacteria grow best at temperatures between 10°C and
40°C. It is therefore important to cool milk as quickly as possible.
This can be difficult in the tropics if no cold water or refrigerators areavailable.
Most bacteria will be destroyed during heating. The most effective
temperature depends on the heating time. In other words, heating for alonger period at a lower temperature can be as effective as heating fora shorter period but at a higher temperature.

Figure 9: Pasteurisation

In figure 9, we see:a Direct pasteurisation of milk in a saucepan (method A below)b Pasteurisation of milk in bottles (method B below)
Pasteurisation improves the safety and storage life of a product, while
the taste hardly changes and the loss of vitamins is minimal. A
distinction is made between low and high pasteurisation (see table 2).
Although high pasteurisation initially kills more bacteria, the resulting
milk can usually not be kept as long, because the high pasteurisation
temperature stimulates spores of some bacteria to germinate.
Moreover, the taste of high pasteurised milk has more or less theProcessing techniques29

flavour of boiled milk. Pasteurised milk can be kept for about one
week at 4-6°C if no re-infection takes place.
The pasteurisation temperature to be used depends on the product to
be made of the milk.
? Low pasteurisation is used for milk for direct consumption andcheese.
? High pasteurisation is used for yoghurt, butter and kefir.
Table 2: Time–temperature combinations for pasteurising milk

low pasteurisinghigh pasteurisingtimetemperature
remarks
30 minutes
63°C
quantities >5 litres
3 minutes
68°C
small quantities
20 seconds
72°C *)
industrial equipment
2 minutes
82°C
20 seconds
85°C *)*) continuous flow system; not for small-scale processing

If there is no thermometer to measure the exact temperature, heat themilk to its boiling point.
Pasteurisation methods
The following method A is suitable if you are able to accurately
control both temperature and time. Method B is more hygienic, if theexact temperature of the milk is unknown.

You will need:? raw milk, a heat source, a saucepan with a thick bottom that issmooth on the inside, a thermometer and a means of cooling themilk that has been heated? for method A: a clean wooden spoon? for method B: glass jars with lids or bottles with tops, or plasticbags and sealing equipment.

30

Preparation of dairy products

Method A
Put the milk in a clean saucepan and heat it to 68°C, stirringcontinuously. Keep the milk at that temperature for at least 3 minutes.
Method B
Clean the glass jars with lids or bottles with tops. Fill them with milk
and close the lids. Submerge the jars and bottles in a large pan filledwith water. Heat everything to 80°C and keep it at that temperature forat least 10 minutes.

When using method A, let the milk cool down as quickly as possible.
The best storage temperature is 4°C. The proper storage temperature
for a soured milk product or cheese can be found in chapters 6 and 7.
If you are using method B but are not able to maintain a constanttemperature of 80°C, the best alternative is to heat the water in the pan
until it boils and keep it boiling for some time. It is important to store
the pasteurised or boiled milk at 4°C. At this temperature it can be
kept up to one week. Handle the boiled or pasteurised milk with care
to prevent re-infection.

4.2

Cooling

Storing milk at a low temperature will greatly reduce the growth ofbacteria. Bacteria develop much slower in cold milk. The best storage
temperature is 4°C. If this temperature cannot be achieved, store themilk in a dark place at the lowest temperature possible: see table 3.
Table 3: Quality of raw milk after storage for 24 hours under
different temperature and hygiene conditions
Storagetemperature (°C)
4
10
20
35

Very hygienic
conditions
good
good
poor
bad

Hygienic
conditions
good
poor
poor
bad

Processing techniques

Unhygienic
conditions
poor
poor
bad
bad

31

Without cooling, raw milk will spoil within a day.
Put the hot pasteurised or boiled milk in a clean container (the hightemperature will disinfect the container). Let it cool down as quickly
as possible, preferably in a large pan with cold water (refresh thewater if it warms up). The best temperature for storage is 4°C. Cooling
down in air, e.g. in a cold cellar or a refrigerator is very ineffective as
the transfer of cold by air is very slow. If you use a pan with cold
water make sure that no water enters into the milk because it would
contaminate the milk again. Add ice cubes to the cooling water, if
available. Stir both the water and the milk during cooling with a clean
spoon, using different spoons. Figure 10 shows how to cool milk.
As mentioned above, properly pasteurised or boiled milk can be kept
for about one week if stored at 4°C. At 10°C it will spoil quickly; if it
is 15°C or warmer, it should be consumed the same day (see table 3).

Figure 10: Cooling pasteurised milk

32

Preparation of dairy products

4.3

Souring by fermentation or acidification

Another way of increasing the shelf-life of milk is to ferment it into
soured milk products. Part of the milk sugar is converted into lactic
acid by bacteria, for example by the yoghurt bacteria Streptococcus
thermofilus and Lactobacillus bulgaricus or the bacteria that grows atroom temperature Streptococcus lactis.
Fresh raw milk can be left to sour spontaneously, but then you cannot
control which bacteria are growing. It is better to sour the milk withthe help of specific lactic acid bacteria as a starter culture after themilk has been pasteurised. Quality and taste are influenced by the
products that the different lactic acid bacteria produce.

4.4

Creaming

Cream is made from the fat that rises to the surface of cow milk. A
layer of fat forms on the surface of the milk after it has been left tostand for at least half a day. After a day this layer contains about 20%
fat. The simplest way of collecting it is by skimming it off the top of
the milk. Sheep and goat milk do not cream easily. You will need acreamer or centrifugal separator to obtain good results. You should be
able to get about 1 - 2 litres of cream from 10 litres of milk.
The skimmed milk which remains after the removal of the cream isstill very nutritious, because it contains nearly all the protein of themilk. You can either drink it or use it for the production of sour milkor cheese.
Sour (fermented) cream and sour (fermented) milk are produced byincubation of inoculated fresh cream or fresh milk. A culture of lactic
acid bacteria is used for inoculation of the fresh milk or the fresh
cream.
Butter (80% fat) and buttermilk are made by churning cream or milk.
One hundred litres of milk with a 4% fat content produces 20 - 30
litres of cream, which yields about 4 kg of butter. However, butter is

Processing techniques33not an important product in tropical countries because it melts easily
at high temperatures and it is expensive. There is generally little
demand for butter. Butter and cream can be used to make ghee. Ghee
keeps better than cream and butter as it contains practically nomoisture; it is almost pure milk fat.

Figure 11: The milk of buffaloes is rich in fat

34

Preparation of dairy products

5Starter cultures

In tropical countries it is often difficult to prevent raw milk fromspoiling before consumption. One way to avoid this is to allow themilk to acidify or ferment. This is done by adding lactic acid bacteria
to fresh milk. The addition of lactic acid bacteria is called inoculation.
There are several groups of fermented milks. The principal differences
between these groups are:? type of milk used (cow, goat, sheep, buffalo, camel or mare)? type of fermenting flora? the way the milk is processed either before or after fermentation.
Various kinds of lactic acid bacteria produce various kinds of sour
milk. Yoghurt, dahi, laban, nono, kefir and koumiss are all produced inthis way. These products differ in flavour, colour and consistency.

5.1

The development of lactic acid bacteria

Bacterial growth shows a specific pattern comprising the following
consecutive stages: adaptation phase (A), a period of rapid
multiplication (B), a stabilisation period (C) and a decreasing phase(D). See figure 12.

Figure 12: Development of lactic acid bacteria
Starter cultures35

After inoculation with the bacteria, the milk starts souring. In practicethe whole souring cycle takes one to two days. In this period one canrecognise the four growth phases of bacteria as follows.
Adaptation phase
During this period, bacteria, of which only a relatively small number
is present, have to adapt to their new environment. Multiplication isstill very slow. The length of the adaptation period depends on thetype of bacteria, their viability, the temperature of the milk andwhether there are any bacterial growth inhibiting factors present.
Period of rapid multiplication
The bacteria, after adjusting to their new environment, multiply
rapidly and start fermenting milk sugar (lactose) into lactic acid. The
milk gets thicker because of coagulation of the proteins and the taste
becomes sour.
Stabilisation period
During this stage, the number of bacteria remains constant. The reason
for this is that they do not thrive in the acidic milk.
Decrease of the number of bacteria
Due to the exhaustion of the nutrients of the food source and the
production of lactic acid, the bacteria become inactive and die aftersome time.
Note: The gradual inactivation of the bacteria is the reason why you must not
wait too long before adding part of a desirable bacterial culture to fresh milk
(inoculation).

5.2

Cultivation of starter cultures of lactic acidbacteria

Starter cultures of lactic acid bacteria can be obtained from specialised
firms and laboratories or from other dairy plants. Most of the starter

36

Preparation of dairy products

cultures from the laboratories and specialised firms are freeze-dried;
dairy plants generally have fresh (liquid) starter cultures available.
If starter cultures cannot be obtained easily, it is recommended thatyou cultivate and maintain your own cultures. That way it is notnecessary to buy a fresh starter culture each time you want to makecheese or a soured milk product. If fresh raw milk is stored at ambient
temperatures the bacteria in the milk (including the lactic acidbacteria) will develop, after some time acid will be formed and themilk will curdle. The lactic acid bacteria that develops can be used forthe fermentation of the product; see section 5.5.
During this spontaneous souring, however, undesirable microorganisms could contaminate the milk. It is therefore better to use acommercial starter culture. When small quantities of products are
made, a small amount of fresh yoghurt, whey or sour milk (orbuttermilk) can be used as a starter culture. Experience has shown thatthe use of a starter culture produces a more consistent and better
product than the use of naturally soured milk.
It is difficult to keep the starter culture fresh and active, especially
under tropical conditions and with limited resources. The cultivationof the culture requires good hygiene and proper temperatures.
Different products, such as yoghurt and cheese, require different
cultures of lactic acid bacteria. If you can obtain a freeze-dried powder
culture, follow the instructions on the package. Once the seal of the
package has been broken, the bacteria will not survive for a long time,in any case not longer than 6 months.

5.3

Growth of starter cultures

To make a starter culture you will need:? fresh milk
? a thermometer? a heat source

Starter cultures37

? a normal size (1 to 2 litre) pan with a lid? a fresh starter culture or a freeze-dried starter culture? a place to store the culture that has a constant warm temperature(e.g. an insulated box)
? a spoon or a small measuring cup? glass pots that can be closed properly.
The equipment can be sterilised by immersing spoons, ladles and lids
in boiling water for at least 5 minutes.
Milk used for the production of a starter culture should be handled
under very hygienic conditions. Either whole or skimmed milk can beused as a base, but as the fat in the milk has no use, it is more
economical to use skimmed milk. Boil the (skimmed) milk for at least
5 minutes in a saucepan. Transfer the boiled milk into a clean glass(use only glass!) jar, which can be properly closed. Normal clay
pottery is porous and therefore more difficult to clean, so it can easily
become a source of bacterial contamination. Cool the milk to theproper fermentation temperature. This temperature can be found in the
instructions for use on the package of the starter culture.
For the production of the first starter culture you must use a freezedried culture or an active fresh liquid culture. If a freeze-dried powder
is used: mix the powder with a small quantity of milk to make asmooth paste (everything coming into contact with the starter paste
should be disinfected). Add more cold, boiled milk (follow the
instructions on the package) and leave the mixture at the proper
temperature as indicated in the instructions for using the powder. Dry
starters are usually weaker than fresh cultures and should therefore
preferably be re-inoculated and incubated one time more before being
used to make other products (see figure 13).
If you start with a fresh liquid culture a quantity of 1 to 3% has to be
added to the milk for inoculation. For freeze-dried starters follow the
instructions on the package. The inoculated milk has to be incubatedat a certain specific temperature for some time (generally 20 - 24

38

Preparation of dairy productshours at a temperature of 18 – 20°C). In that time the bacteria multiply
and the milk ferments.
Different products, like cheese and yoghurt, require different starter
cultures. Incubation time for yoghurt is much shorter, generally 3 - 6hours at temperatures between respectively 45 and 38°C.

Figure 13: Cultivation of a starter culture

Bacterial growth starts at the moment the starter culture has been
mixed through the milk. From this point, a constant and correcttemperature must be maintained. There are a number of ways to keep
the culture at the desired temperature. It can be poured into a sterilised
thermos flask while warm, or an insulated box can be used to incubate
a jar containing the souring milk. Covering the closed saucepan with ablanket or placing the closed pot under the bed covers will also help tokeep the temperature constant.

Starter cultures39

Once the culture has been fermented, it can be used to make sour milk
products and cheese.

5.4

Maintenance of starter cultures

Maintenance of the culture involves daily transfer of the existing
culture to freshly boiled and cooled milk. Use skimmed milk if
possible. This process is needed to prevent the bacteria from becoming
too weak and thus useless. Part of the existing culture is used toinoculate fresh milk, which in turn is fermented to become the new‘mother culture'. The rest of the original culture can be used to makeproducts such as yoghurt, cheese and buttermilk. The addition of 1 –3% culture to the milk should be adequate. After incubation the milk
has to be cooled, e.g., by putting it in a refrigerator, and incubatedagain for 20 - 24 hours. If a refrigerator is available, inoculation could
be done on a weekly basis, but it is better to refresh the starter 2 times
per week. The mother culture must be kept properly cooled.
If the culture is not used immediately, it can be kept, withouttransferring, for one week at most in a cool place, e.g. a refrigerator.
After repeated use, the culture may become less active or its quality
may decrease because it may not have the desirable fresh, sour flavour
any more. If it appears that the activity of the culture is decreasing
after some time, a fresh starter should be used.
A general guideline is to discard the culture when it takes longer than
10 hours to make yoghurt at 40 - 45°C, or 30 hours for milk to becomesour after the addition of the starter culture to the milk (temperature at
20°C). If the fermentation seems slow, the coagulum is rather thin anddoes not have a fresh smell, you may be sure that the starter bacteria
are weakened.
Instead of using milk, one can also use milk powder. It is absolutely
essential to use clean, well-boiled water to dissolve the milk powder.
Instead of a culture, a portion of the ready-made product (yoghurt,sour milk or buttermilk) can be used if this product was made shortly

40

Preparation of dairy productsbeforehand, but this method is not very dependable. The safest but
also most expensive method is to use a new starter each time, certainly
when fermented milk products are made irregularly, i.e. not every
month. This will save the effort of frequent inoculation of a new
culture.

5.5

Preparing your own culture

If starters cannot be obtained easily, it is possible to cultivate simple
lactic acid starters from raw milk (see figure 14). Store raw milk atambient temperature until it has developed sufficient acid to curdle.
For instance: leave 1 litre of fresh, raw milk to stand for 24 - 48 hours
at 20-30°C.
After souring of this milk, a second quantity of milk is then boiled andcooled to the temperature at which the milk is usually fermented in the
production process. The top layer of the available sour milk isskimmed off with a spoon or ladle (to remove micro-organisms, which
stick to the fat globules) and this cream is thrown away. Add a small
quantity of this soured milk (called inoculum) to the boiled milk
(about 2 - 5%) and mix them.
After 24 hours of incubation at ambient temperature, again a fresh
quantity of boiled milk with a temperature of about 20°C is inoculatedwith a small quantity (1-2%) of the second batch of sour milk (seefigure 14). This procedure is repeated daily for about one week.
Fermentation of the milk should take place in a jar or a bottle, whichmust be closed with a clean cover that is also dust free. It is essentialthat all the utensils and tools used (jars, spoons, etc.) are clean anddisinfected. Prevent contamination after disinfection!
After this period of cultivation the sour milk can be used as a starter,
because the lactic acid bacteria will have overgrown other bacteria
almost completely.

Starter cultures

41

Figure 14: Isolation and production of a simple starter culture; thefinal starter culture can be used for inoculation at 1 – 3% and so on

42

Preparation of dairy products

Problems with the fermentation can have the following causes:? The milk contains antibiotics, e.g. penicillin (because the cow had
been treated with antibiotics).
? The milk has been contaminated with hydrogen peroxide or
disinfectants; this slows down fermentation.
? The incubation temperature of the milk is too low (below 18°C).
? The temperature of the milk at the moment of the inoculation was
too high (above 40°C).

Starter cultures

43

6

RecipesFigure 15 gives a rough overview of the different dairy products thatcan be made from milk.

Figure 15: Manufacturing of milk into dairy products

Every recipe in this chapter starts with a list of the ingredients andequipment needed. The actual preparation is then described. Successdepends on a lot of factors, so do not give up if you do not end up withthe desired results the first time. Experimentation is necessary and you
will probably have to adapt the recipes.
Several preservation techniques, like cooling, heating, drying, souring,salting, etc., are relevant to most recipes. Different types of milk can

44

Preparation of dairy productsbe used, which give different results. Take great care when cleaning
all pans, dishes and utensils; see chapter 3.

6.1

Cream

You will need raw milk and a heat source.
Method A
After leaving milk to stand for about 24 hours at as low a temperature
as possible (4-12°C), the cream can be skimmed off using a spoon orsaucer. This method makes use of the fact that cream rises and thenstays on top of the milk. It contains most of the milk fat. Only cow
milk readily produces cream this way; other kinds of milk need a handcreamer (centrifugal milk separator) to separate cream and milk.
Method B
Materials: a hand creamer (milk separator), two big bowls.

Heat the milk slightly to a little over 40°C and pour it into the upper
bowl of the separator. It is important to turn the handle at a constant
speed during the separation. After separating the cream from the milk,
pasteurise both cream and skimmed milk.
The use of a separator produces more cream and leaves skimmed milkwith less fat. A disadvantage is that the separator has to be cleaned
thoroughly, including the disks, which takes much time. A handcreamer is a complex tool. Never buy a second-hand creamer before
having checked that it works well. It might lack some irreplaceableparts or may be corroded or damaged.
The cream can be kept for a few days if it has been pasteurised. It canalso be used for the preparation of various recipes. Cream can be used
to make butter, for example.
The skimmed milk that is left after the cream has been removed stillcontains a lot of nutrients (protein, fat, milk sugar, etc.) and can be

Recipes45

used for direct consumption or for the production of soured milk or
low-fat cheese.

6.2

Sour cream

You will need:? fresh pasteurised cream? a saucepan? a thermometer? a metal or wooden spoon? a starter culture or fresh fermented milk
Cool the cream after pasteurisation to 18°C. Add 10 – 30 ml (1 – 3%;
equal to 1 - 2 tablespoons) of sour milk or a starter culture to one litreof cream while stirring. Let the mixture become sour at a temperatureof between 16 and 18°C, stirring it once after a number of hours toallow it to ferment evenly. After 24 hours the cream should be
sufficiently sour and ready for consumption.

6.3

Butter

You will need:? pasteurised cream, sour cream or sour milk
? a heat source? a pan? a thermometer? cold water? sour milk or a starter culture? a container for churning? a sieve? a bowl? a tray for kneading? wooden spoons? fine salt if available (optional)? packing material, e.g. greaseproof paper or a jar? clean water46

Preparation of dairy products

Butter is made by churning one of the following products: cream, sour
cream, or sour milk. If you do not have enough milk from which toskim off the cream, the milk can be soured and churned as a whole(provided that the fat content of the milk is rather high; above 4%).
But sour cream is better to churn than sour milk.
It is only possible to manufacture sweet cream butter if the production
and handling of the milk, cream and butter are exceptionally hygienic
and the cream has undergone after pasteurisation a cold treatment by
storing it for at least 12 hours at temperatures below 10°C.
Heating and souring
Heat the milk or cream to a temperature of 85°C. Let it cool down to
18°C as quickly as possible (use a thermometer) using cold runningwater on the outside of the pan.

Add 10 - 30 ml (about 1 - 2 tablespoons) of fresh fermented sour milk
or a starter culture to one litre of milk or cream and stir. After about 24
hours at 16 to 18°C, the mixture will become thick and sour enough to
be churned.
Churning
During churning the cream, sour cream or sour milk will be mixed
intensively with air. This process causes fat globules to flocculate (orstick together), producing butter and buttermilk.

The simplest way to make butter from small quantities of milk is byusing a bottle or a jar that can be covered with a well-closing lid or asimple bowl with beaters. If large quantities of milk or cream areavailable, you should consider acquiring a real churn. There areseveral types available. The churn tub is a simple method, which isoften used in the tropics. A cheap and practical domestic churn is a
glass pot with a paddle attached to a screw top. The paddle can beturned manually. This churn is difficult to clean. It is best to rinse itwith water before use, in order to prevent the butter from sticking to
the sides.

Recipes47

Churns should not be filled more than one third with soured milk orsour cream. Churn with a regular up and down or sideways
movement. Stop churningwhen the butter particles reachthe size of rice grains or peas
and the buttermilk looks rather
liquid. If, after 30 minutes, nograins have yet been formed,youcanchangethetemperature by adding a little
clean cold or warm water. See
also the remarks at the end of
this chapter. The amount ofadded water should never bemore than 25% of the total Figure 16: Using a jar to makeamount of churned cream or butter
milk.
The butter particles will float to the top of the buttermilk, because
butter is lighter than buttermilk. This makes it easier to separate thetwo products by pouring off the buttermilk through a coarse sieve.
Never add too much water, otherwise the buttermilk will become toowatery.
Washing
Washing of the butter grains is not necessary. However, if very cleanwater is available, it can improve butter quality.

Washing the butter can be done in two ways:
1 Fill the churn 2/5 full with clean, cold water. Wash the butter by
churning it for about 3 minutes. This can be repeated, if necessary.
The idea is to remove part of the remaining buttermilk from thebutter particles. It is important to remove as much as possible inorder to produce butter that can be kept for a longer period. Afterwashing, the butter particles can be skimmed off or the buttermilk
can be drained.

48

Preparation of dairy products

2 If small quantities are available, the butter particles can be washedusing a sieve. Put the sieve on top of a bowl and pour the mixture
through it. Make sure that during churning the butter does not
become one big lump, otherwise it will be difficult to wash - in case
you want to do this.
Salting (if preferred)
Salting is not necessary for preservation; many people, however, likethe taste of salted butter. The butter can be slightly salted (according totaste) by kneading in about 10 grams of salt to each kilogram of butter.
Mix the butter again the next day in order to allow the salt grains todissolve.
Kneading
Kneading the butter is important in order to get a nice, smooth
product. It helps to distribute the moisture and this improves quality
and shelf life, provided that kneading is done in a hygienic way.

Use a clean, well-rinsed kneading board. Knead the butter with theback of two wooden spoons until drops of water and buttermilk are
not perceivable any more and the butter has a nice, smooth surface.
Remove drops of buttermilk during this process. Instead of a wooden
spoon, a wet roller or bottle can be used. If none of these are available,
just use clean hands to knead.
Storage
Butter should be stored in a cool, dark place. Put it in a pot or wrap it
up in greaseproof paper or aluminium foil. After some time, one to
two weeks, the surface of the butter can be covered with moulds. This
mould formation can be partially prevented by sprinkling salt on thesurface or by wrapping the butter air tight. Moulds only grow if
oxygen is available.

Butter can also be frozen. However, after defrosting the butter willrather soon have an off-taste. It is therefore a good idea to divide theRecipes49

butter into smaller portions before freezing. Salted butter is lesssuitable for freezing.
Remarks
1 If milk has gone sour without the use of a starter, but it still tastes
and smells fresh, it can still be churned.
2 Churning can take from 5 to as much as 60 minutes. A number offactors may influence the time needed, for instance:? type of animal the milk came from? the fat content of the cream? treatment of the cream; the cream must have had enough time (atleast 12 hours at 10 – 18°C) before churning for crystallisation ofpart of the fat to take place? feed eaten by the animal; feed influences the crystallisation (=melting point) of the fat? the temperature of the cream during churning.
This last aspect is also dependent on the melting point of the fat.
If the cream is too cold, the fat globules do not easily stick
together and churning will take longer. If the temperature of thecream is too high, churning will go quickly and the butter grains
will not stick together and butter will not be formed. A goodchurning temperature is 15 – 20°C.
3 Butter has a limited shelf life. It can become mouldy or rancid. An
unpleasant cheese-like flavour may develop due to the deteriorationof its protein. An alternative is ghee (see below), which does not
spoil as quickly as butter. Ghee is produced by removing the lastwater remnants from butter by heating the butter and letting thewater evaporate, or by melting butter and draining the water, which
separates from the fat.

6.4

Buttermilk and sour milk

Buttermilk is a by-product of the butter-making process. The taste canbe more or less sour depending on the sourness of the cream or themilk, which is used for butter making, or on the degree to which itsours after churning.

50

Preparation of dairy products

It is also possible to make a product like soured buttermilk using milk
or skimmed milk, by inoculating it with sour milk and letting it
ferment for one day. For the fermented milk you will need: fresh(skimmed) milk, a heat source, a wooden spoon, fresh fermented milk
or buttermilk or a starter culture, a saucepan with a thick bottom, and athermometer.
Heat the fresh (skimmed) milk to boiling point, stirring all the time.
Cool it down to 18 – 20°C, for instance in a large pan with cold water.
Add 10 – 30 ml of sour milk or buttermilk or a starter culture per each
litre of milk (1%). Leave for it 18 - 24 hours at room temperature (18– 20°C); if the surrounding temperature is higher, fermentation time
will be somewhat shorter. After this the sour milk is ready. Store it in acold place (cool basement or a refrigerator), if you want to keep it forsome days.

6.5

Ghee

To make ghee, you will need:? butter? a heat source? a pan? a metal spoon.
Heat the butter until water and fat form separate layers; the fat will
float on top. There are two ways to remove the water:? It can be removed by further heating. The water present will
evaporate.
? It is possible to remove the layer of fat with a spoon. This fat should
then be heated again. The scum, which will form, has to beskimmed off regularly, preferably with a skimmer. The colour ofghee can vary from almost white to dark brown. A rancid flavour is
acceptable, but if it tastes burnt it should be discarded.

Recipes

51

6.6

Koa

Koa or khoa is a type of concentrated milk. You will need:? fresh (unboiled) whole or skimmed milk
? a heat source? a shallow, clean, wide, iron pan with a thick, flat bottom? a flat, clean metal utensil to stir with (e.g. a flat pancake spatula).
Fill the pan with the milk up to 30 to 50% of its capacity. Bring themilk to boiling, stirring continuously. The water will evaporate andafter some time the milk will reach a certain viscosity, this means themilk will thicken. Take great care to scrape the sides of the pan during
stirring. Once the milk has reached a dough-like consistency andstirring does not prevent the mass from sticking to the side of the pan,you can remove it from the heat source and lower the temperature byat least 20°C. At this point the water content should have been reduced
to about 40% of what it was. Take the lump of koa out of the pan, put
it on a cold surface and flatten it. After cooling, the koa will be firmand can be cut into squares. It will have a sweet, nutty flavour. Koa
can be kept only for about 2 - 5 days because of possible re-infection.
The preparation of koa requires much time (a few hours) and fuel, on
top of which 1 litre of milk produces only 0.4 litres of koa.

6.7

Rabi

Rabi is sweetened, concentrated milk. During concentrating, sugar isadded from time to time. You will need:? (unboiled) milk
? a heat source? a wide, shallow iron pan with a thick bottom? a flat metal scoop? sugar? scales.

52

Preparation of dairy products

Add sugar to the milk during the heating process (maximum 300 g per
litre of milk) and follow the same procedure as for koa. Lumps ofsugar will often be found in the end product.

6.8

YoghurtYoghurt is produced when milk is soured by certain lactic acidbacteria, which prefer growing temperatures far above room
temperature: 37 – 45°C. The milk should first be heated to 85°C or
higher. A high pasteurisation temperature (above 72°C) gives a better
consistency (thickness) to the final product. After the milk has beensoured, the resulting yoghurt can be used to make more fresh yoghurt
by adding it to fresh milk.
Basic recipe for yoghurt
You will need:? fresh raw milk
? a heat source? a saucepan? a spoon? a thermometer? cooling facility(e.g. a large pan with cold water)? a cool place (refrigerator or cellar)? starter culture for yoghurt or some
fresh yoghurt? thermos flask or a box covered with a blanket

Heat the milk to 85°C or higher and keep it at this temperature for 3
minutes. Cool the milk to 45°C. Add 30 ml (2 - 3 tablespoons) of fresh
yoghurt to each litre of milk; the yoghurt should not be more than 2days old. Instead of fresh yoghurt you can use a yoghurt starter
culture. Mix the milk and the starter and leave it to ferment. The timerequired for the milk to turn sour depends on the temperature. To give
you an idea:? at 40 - 45°C it takes about 3 to 6 hours

Recipes53

? at 35 - 37°C it takes about 20 to 15 hours? at 30°C it takes about 24 hours
The ideal temperature to make pleasant-tasting yoghurt with a firm
consistency is 40 - 45°C. It is not possible to produce yoghurt at
temperatures below 30°C or above 50°C. The correct temperature canbe maintained using an insulated box or a blanket. Yoghurt is ready for
consumption once the incubation period is finished. If cooled, yoghurt
can be kept for one week.
Using a thermos flask
Heat the milk to at least 85°C, then cool it to 45°C. Pour 90% of themilk into a thermos flask, which has been rinsed with hot water. Mix 1- 2 tablespoons of fresh prepared yoghurt (or yoghurt culture) with therest of the milk and add this to the thermos flask. Close the flask welland leave to stand for 3 - 6 hours. Remove the yoghurt from thethermos flask and store in a cool place. Yoghurt made of sheep milk isvery firm and therefore not suitable for fermentation in a thermos
flask.
Yoghurt made from milk powder
Make milk from milk powder according to the instructions on the
package, but add 10 to 15% extra milk powder. Dissolve the milk
powder in water, heat it to boiling point and let it cool down to 45°C.
Stir in 1 - 3 tablespoons of fresh yoghurt or a yoghurt culture per litreof milk. Cover the saucepan and put it in a warm, insulated place.
After 3 - 6 hours this (firm and concentrated) yoghurt should be readyfor consumption.
Remarks? It is best to use fresh milk to make yoghurt. Milk powder can also
be used. Sterilised milk may give a thinner yoghurt than pasteurisedmilk.
? After incubation, cooling is desirable, preferably below 10°C, so
that souring is stopped (this retains the pleasant taste) and the54

Preparation of dairy products

bacteria remain more viable, allowing the yoghurt to be used toinoculate milk again.
? Make sure the milk ferments as quickly as possible, preferably at 40- 45°C rather than 30°C. Harmful bacteria have less opportunity todevelop if the fermentation process goes faster.
? Thicker yoghurt can be produced by adding 2 to 3 tablespoons ofmilk powder to each litre of milk before heating it to 85°C.
? It is not advisable to use fruit yoghurt from a shop as a starter
culture because it contains a lot of additives. Plain yoghurt from ashop can be used if it is not too old. Sterilised yoghurt is notsuitable either, because the yoghurt bacteria have been killed by thesterilisation process.
? When using yoghurt from a carton or a pot as a starter, first remove
the top layer and take the yoghurt from the centre to make fresh
yoghurt. This is because the bacteria in the middle are probably themost diverse and active.
? Stir the product as little as possible before removing some, to avoid
the extra risk of incorporating undesirable bacteria.

6.9

Kefir

Kefir, like yoghurt, is a milk product first discovered by the nomadic
tribes living in the cold areas of the Caucasus. When making kefir,acid, gas and some alcohol are produced. Like sour milk andbuttermilk, it has a special aroma which is different from that of
yoghurt. Kefir is made by using a 'yoghurt plant', which is actually amisleading name as it is not a plant and it has nothing to do withyoghurt.
The 'yoghurt plant' is in fact a cauliflower-like lump of chalky crystals
and micro-organisms consisting of yeasts and bacteria. The yeasts
produce alcohol and gas, while the bacteria convert the milk sugar into
lactic acid. You may be able to obtain a piece of this from someone
who regularly makes kefir. If not, get some dried kefir granules at the
local market.

Recipes55

You will need: fresh raw milk,a saucepan, a heat source, athermometer, a clean pan, aglass bottle with wide neck, abottle which can be closed
tightly, kefir granules or a'yoghurt plant', a sieve, coolingfacilities, clean water, ateaspoon, and a cool place tostore the product.
Boil the milk and put it into abottle, which has beenthoroughly cleaned and rinsed
with hot water. Do not fill thebottle completely; let the milk Figure 17: Kefir is a thick, creamy,
cool down to 20°C (use a frothy drink with a sour taste andthermometer).
Add
one smelltablespoon of kefir granules
soaked in water to each half litre of milk in the bottle and cover itloosely so that the gas produced can escape. You can use a fresh
yoghurt plant instead of the soaked granules. Keep the bottle at atemperature of 16 to 18°C. After 24 hours the milk will have become alittle thicker, forming some froth: this is kefir. Sieve the kefir and use
the (washed with clean water) granules, which remain in the sieve to
make fresh kefir again. The kefir is now ready for consumption or canripen for some days to get more flavour.
Ripening of the kefir
The kefir can be left to ‘ripen’, during which time further fermentation
takes place. This is essential to create kefir’s characteristic qualities.
Pour the kefir into a well-cleaned bottle, which can be closed, or abottle with a clip fastening and do not fill more than 3/4 because gas
forms during ripening.

56

Preparation of dairy products

Leave the bottle at about 15°C, but do not store it for more than 3days. Towards the end of the ripening process the whey separates andcan be incorporated again by stirring or turning the bottle. The end
product is a thick, creamy, frothy drink with a sour taste and smell andthe produced carbon dioxide is perceivable. If the kefir is left to ripen
for more than 3 days, the milk may curdle and the drink becomes too
sour. The temperature and the time are important as they determine theflavour. The kefir can be kept in a refrigerator or a cellar for a few
days.
Storage of the kefir granules
If kefir production is stopped for some time, the kefir granules can bedried as follows: Put them into a sieve and rinse well with clean water
until all remaining milk is removed. Place them on a clean cloth andleave to dry in a clean place, but not in the sun, until the granules haveshrivelled up. The granules can be kept in a closed bottle in a coolplace for 12 to 18 months. The rinsed granules can also be kept in afreezer.

Kefir granules can also be kept in a pot with water at 4°C, but they
become inactive after 8 to 10 days.
Remarks? There is a greater chance of failure with kefir than with yoghurt.
The end product may not only taste bad, it can also be unhealthy. In
order to produce good kefir, the appropriate hygiene should beapplied. Care should also be taken not to work at too hightemperatures.
? The shelf life of kefir is the same as for yoghurt, sour milk andbuttermilk: its quality will rapidly decrease if it is stored too long.
At 5° C, soured products can be kept for about ten days; at 10°C
this is three days, and 20°C is too high.
? Kefir may be too sour or too yeasty (due to an incorrect balance
between the activity of the bacteria and yeasts). A fishy orammonia-like taste can be the result of a breakdown of proteins by
undesirable bacteria, which enter due to insufficient hygiene.

Recipes57

KoumissKoumiss is a sour milk product similar to Kefir. It is manufactured
from mare milk.

Figure 18: Cow milk accounts for 91% of the world's milk
production (see section 2.2)

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Preparation of dairy products

7

CheeseCheese is a product that has been made for centuries. Virtually all thenutrients present in milk are concentrated in cheese (see table 4).
There is a huge assortment of cheeses. They can have various
compositions; we make a rough distinction between fresh cheese andmatured cheese, and between soft cheese and hard cheese. Freshcheese can be consumed immediately after production, whereas
matured cheese has to be stored after processing to develop flavour
and a good consistency. Soft cheese has a higher water content than
hard cheese; moreover hard (or semi-hard) cheese generally has aclean, dry rind. Soft cheeses and hard cheeses can be matured forsome weeks or even up to a number of years.
Table 4: Rough composition of milk and some types of cheese
Product

Milk
Skimmed milk
Fresh cheese (whole fat)Fresh cheese (low fat)Cream cheese (fresh)
Soft cheese
Semi-hard cheese
Hard cheese

Content (in % weight) of
Water

Fat

Protein

87.5
91
73
83
57
51
42
30

3.5
0.1
10
0.2
32
25
30
35

3
3
10
13
9
19
25
30

Salt
(sodium chloride, NaCl)less than 0.1
less than 0.1
less than 0.1
less than 0.1
0.5
2
2 – 2.5
2 – 2.3

Cheese production in the tropics is typified by specific problems;consequently, production processes and end products differ from thosein Western Europe.
? Outside the temperate zones, high temperatures and very high air
humidity must be taken into consideration. Both these factors areunfavourable for cheese making, in particular for the maturation ofcheese.

Cheese59

? Milk is often available in small quantities, while its quality may not
be up to standard. In particular, its hygienic quality andcomposition may leave much to be desired.
? Hard and semi-hard cheeses require good-quality milk andhygienic processing. Moderate temperatures are needed for goodripening and storage of these cheeses. In warm and hot climates
most cheeses are produced on a small scale and cannot be stored
for a long time. Therefore generally these are soft cheeses.
? In many tropical and subtropical countries, very matured cheese is
not very popular. Most consumers are not used to the distinct
flavour and smell of such cheese.
The shelf life of cheese can vary from several days to some months
and even to some years, depending on its processing.
Fresh cheese can, like fermented products, be stored for only a shorttime; it must be consumed immediately or within a few days. The
keeping quality of such cheese can be improved by cold storage andsalting. Fresh cheese generally does not have a rind and is packed in awrapping or a package. Most of the fresh cheese has been curdledusing only an acid; it cannot be ripened and it should be consumed
within a couple of days.
Soft cheese is processed by using acid and rennet, in most cases itmatures for some weeks or even some months. Soft cheese generally
has a rind and often also a microbiological flora on the surface of therind (like Camembert and Brie).
Semi-hard and hard cheese can be kept well for 3-4 months or more.
Cheese which is able to continue ripening should not be kept in arefrigerator, but in a cellar or cool place at 10-15°C. Where applicable,
information and instructions will be given in the following recipes on
keeping qualities and ways of storing products.

60

Preparation of dairy productsCheese making has three main goals:
1 Concentration of the milk into curd, whereby a great deal of theliquid part of the milk, the whey, is removed.
2 Preservation of the curd. Acidification of the curd and the salting
process are important, along with a well-closed cheese rind or
effective wrapping of the cheese.
3 Maturation of the cheese, in order to get a good taste, flavour andconsistency.
The cheese-making process has some essential steps. These are:1 coagulation of protein of the milk, whereby the fat is incorporated
in the coagulated protein
2 draining of the whey
3 acidification of the curd
4 collection of the curd and combined growth into a cheese
5 salting
6 maturation
The processing of fresh cheese follows steps 1 to 3; matured cheeseneeds steps 1 to 6.
The basic operations in cheese making will be discussed in thischapter:? the treatment and quality of the milk used to make cheese(pasteurisation and/or standardisation)? the coagulation (curdling) of the milk using acid or enzymes? the separation of the curd and whey
? the collection and preservation of the curd (heating, collection,pressing and salting)? the maturation (ripening) of the cheese.

Cheese61

7.1

Utensils for making cheese

When making cheese, you will not always need all the utensils
described below. Decide beforehand which you will use, and makesure that they are clean and rinsed with clean water. It is preferable touse utensils made of stainless steel or glass.

Figure 19: Utensils for cheese making

The utensils used during cheese making are:1 a thermometer with a range of 20 – 100°C
2 a measuring cup
3 a bucket for coagulation of the milk
4 cheese moulds, which can be made in various ways (see below)
5 cheesecloth, its size depends on the size of the mould
6 cutlery and other tools such as:? spoons to measure rennet and/or acids? a knife to cut curdled milk
? a skimmer to scoop curd out of whey, or a colander.
Cheese moulds can be made from various materials e.g. wood, plastic
or metal. Metal materials should be non-rusting. Do not use plastic
tubing used in construction as it can release poisonous substances. Cut
the moulds lengthwise and drill holes from the inside out. Plastic
moulds for the production of soft cheese are also commerciallyavailable. Wooden cheese moulds can be used as well.

62

Preparation of dairy productsCheese that will have a closed
rind after pressing is never placed
directly into a mould. Instead, aclean cloth of linen or cotton is
first placed in the mould and it isthen filled with curd. The
cheesecloth is then folded closed.
Figure 20: Cheese moulds

To make hard or semi-hard cheese
you will also need the following:? a curd knife to cut the renneted milk
? a cheese press

Figure 21: Some examples of cheese presses

Buy these second-hand if possible or make your own simple press,
paying special attention to the following:? The materials used must not be poisonous.
? It must be possible to easily clean the materials.
? It must be possible to build up sufficient pressure (0.1 to 0.4 kg/cm2
or 2 - 5 x the weight of the cheese).

Cheese63

7.2

The quality of milk used to make cheese

Cheese making begins with hygienic milking. The quality of the milk
used greatly influences the smell, taste and keeping qualities ofcheese. The composition of milk can vary greatly. Just before a cow is
set dry – the period in which a cow is not milked – and just after
calving, the cow milk has a different taste and composition. Milk froma cow with an udder infection is not suitable for human consumption,and therefore cannot be used for making cheese.
Apart from the usual measures taken to ensure good hygiene during
milking, attention must be paid to the following points:
1 Clean the equipment very well.
2 Disinfectants and cleaning agents must never be left in or on
equipment. Disinfectants inhibit the growth of the bacteria of thestarter or souring agent.
3 The room in which cheese is prepared must be kept properly clean.
4 The milk used for cheese making should preferably be pasteurised(15 seconds at 72°C or 30 minutes at 63°C). More intense heating is
not desirable because it reduces the curdling of milk. More rennet
or calcium chloride (CaCl2) is then needed.
5 For the above reasons, milk powder which is strongly heated during
its production (high-heat milk powder) is less suitable for cheese
processing. Only low-heat milk powder can be used.
6 Sour milk neutralised with sodium bicarbonate will not curdle well.

7.3

Coagulation of the milk

The principle of cheese processing is based on the coagulation of theprotein in milk, during which about 90% of the milk fat is
encapsulated. The coagulated mass is called curd, the remaining liquid
is called whey. Curd consists mainly of milk proteins (casein) andmilk fat; while whey mainly contains water, milk sugar (lactose),
protein (serum proteins) and B-vitamins.

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Preparation of dairy products

There are two basic ways to cause milk to coagulate:? using an acid? using a rennet (enzyme coagulation)

Figure 22: Four methods of curdling milk
Acid coagulation
This is mainly used to make fresh cheese. The acid can come frombacteria from the starter culture or from an acid added to the milk.
When using a culture, pasteurised milk is inoculated. Inoculating
agents can be a specific cheese starter culture, whey or sour milk.

Curdling time depends on the amount of inoculating agent added (0.1
- 5% of the milk used to make cheese), temperature (20 - 35°C) andthe starter culture used. It takes 2 -16 hours. When the curd is firm, thecurdling is finished.

Cheese65

When using an added acid, you can use pure vinegar acid, lactic acid,citric acid or any other harmless organic acid. Sometimes a naturalacid such as lemon juice is added. The acid can be added drop by drop
to warm milk (about 80 - 90°C, just after boiling). Milk curdles muchquicker at a high temperature.
The curd is collected by straining the curdled milk through a coarse
cloth. Sometimes the collected curd is pressed a little bit, andsometimes no pressure is applied. These products are consumed fresh.
RennetRennet used in cheese processing can be of animal, vegetable or
microbial origin. The rennet in cheese has two functions.
? Rennet causes the milk to coagulate.
? During ripening, rennet causes milk protein to break down, giving
the typical cheese taste.

Rennet is available in liquid form and as a dried powder. As it is an
enzyme and therefore a biological product, the strength of the liquid
product decreases during storage. Therefore, it is preferable to use thedried form.
The concentration of the rennet is written on the package. The amountof rennet to be added depends on the strength of the rennet and on thekind of cheese you are going to make. When making soft cheese,sometimes no rennet is needed; if rennet is added, only a little isneeded (0.1 ml of rennet to 10 litres of milk). For hard or semi-hardcheeses, about 1.5 ml of rennet is added to 10 litres of milk; assuming
the rennet concentration is 1:10,000. A starter is almost always added
before or while adding rennet.
A number of factors influence coagulation:? Amount of rennet or acid added.
? Curdling temperature. When using rennet a small rise intemperature (for example from 30°C to 33°C) can significantly
reduce coagulation time.

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Preparation of dairy products

? Intensity of pasteurisation. Curdling is reduced when milk has beenstrongly heated. This effect can be neutralised by adding a small
amount of CaCl2; for example 7 grams of CaCl2 per 100 litres ofmilk.
? Fat percentage of the milk. A high fat percentage means more fat
must be encapsulated and curdling occurs a little bit slower.
Preparation of rennet
Rennet from animal origin is prepared from the stomach of suckling
calves or lambs. It is obtained by extraction of the stomachs in a salt
solution with a preservative.

A traditional method formerly used in The Netherlands can be appliedin the tropics:? Take 9 litres of boiled water.
? Add 26 carved calf stomachs, 500 gram sodium chloride (salt) and
200 gram boric acid.
? Store these for at least 10 days and stir once per day.
? After ten days, remove the stomachs from the solution, add another
500 gram salt to the solution and store it for some days more.
? Then, pour it into clean bottles, close these and store the bottles in acool and dark place. Your rennet is ready.
You have to try out the strength of the rennet. Also, the keeping
quality of these rennets is usually poor.
Sometimes the stomachs of the young animals are kept after cleaning,salting and drying. The dried stomachs are easy to transport and areused by some nomadic tribes. In cheese making a piece of driedstomach is then added to the milk.

7.4

Separating curd and whey

Three methods can be followed to separate curd from whey:? hanging the curd/whey mixture up in a clean cloth (see figure 23);

Cheese67

? putting the curd/whey mixture in cheesemoulds, or in cylindrical forms withperforated sides;? first cutting and stirring the curd/whey
mixture, putting the curd in the cheesemoulds and then pressing the cheese.
When making fresh cheese, the first or second
method is usually used. As the whey drains
through the cloth or the mould, the volume of
the curd will reduce to 1/2 or 1/3. Whenmaking ripened cheese, the last method has tobe used to remove sufficient whey from thecurd. The effect of cutting and pressing is Figure 23: Letting
soft cheese drain
described below.

7.5

The use of cheese whey

Whey is the by-product of cheese making. The acidity and thecomposition vary widely with the type of cheese and manufacturing
process used. Whey from rennet-coagulated cheeses is less acid thanwhey of acid-coagulated cheeses. Also, the content of solids varies
depending on the method of cheese making. If the content of solids ishigh, e.g. in the case of the processing of sheep cheese or in the caseof rough curd treatment, the solids of the whey can be processed to awhey cheese. A rather well-known type of whey cheese is the Italianproduct Ricotta.
Manufacture of Ricotta from cheese whey
1 Heat the acidified whey till at least 85 °C or boil it for some time
till the whey proteins have coagulated.
2 Add some salt (0.1%) if desired.
3 Collect the coagulated curd by filtering the mass through a towel ora filter.
4 If you press the curd you will get a hard cheese; if the curd ispressed lightly or not at all, the cheese is consumed fresh.

68

Preparation of dairy products5 Add some salt if you like (if you did not do so before)
6 Store the cheese in the fridge.
Whey as animal feed
If whey is discarded it can cause serious problems as a dairy effluent.
Therefore it is far better to use the whey as an animal feed. It has agood feeding value because of the presence of some of the whey
proteins. It can be used for feeding pigs or young animals like calvesor lambs. Even adult cows or fattening cows can be fed with whey.

It is important that the whey used for animal feed is acid (completely
acidified) at the moment of feeding, otherwise the animals can get
intestinal problems because of the lactose content of the whey.

7.6

Collection and preservation of the curd

The amount of whey (water) in the curd has a great influence on thecheese properties. Maturation time, flavour, consistency, keeping
quality of cheese, etc., all depend on the water content.
Whey contains milk sugar or lactose. This sugar has to be converted
into lactic acid by the lactic acid bacteria of the added starter.
If a great deal of the whey is removed from the curd, you get cheesewith little moisture, therefore a dry and hard cheese, which has tomature a rather long time. If little whey is removed from the curd, you
get cheese with a lot of moisture, therefore a soft cheese. This cheese
has in most cases a sour taste. Since the curd treatment of fresh cheeseand ripened cheese is quite different, they will be discussed separately.
It is important during this step of chease making that the curd does notcool down and remains at about 30 – 36°C. The curd treatment can bestarted when the coagulated milk forms a firm mass. You candetermine this by moving a small strip through the curd: if a smoothclear cut develops when the curd breaks it has coagulated sufficiently.

Cheese69

Curd treatment for fresh cheese
As a rule, to make fresh cheese little whey is removed. After curdlingthe milk, the curd/whey mass is hung in a cloth or placed in cheesemoulds. After 24 hours, enough whey has leaked out and the curd iscooled down. The cheese is then ready for consumption. The
separation of the whey can be stimulated by piling the cloths or cotton
sacks on top of each other so that more whey is pressed out of thecheese.
Curd treatment for ripened cheese
After coagulation of the milk, thecoagulated mass is cut with a sharpknife into square cubes of about 1.5
cm: see figure 24. It is important thatthe cubes are more or less of the same
size and that the cutting is done very
gently.

After cutting, the curd/whey mixture
is briefly left to stand, for about 10
minutes, after which it is carefully Figure 24: Cutting the curd
stirred. After some time it can be
stirred a little bit more vigorously. Most of the whey is removed fromthe cheese vat and the curd is placed in the cheese moulds. The curd isthen pressed (0.1 kg/cm2). After about one hour the pressure can beincreased to 0.4 kg/cm2. Other ways of determining the pressure arerespectively 2 times and then 5 times the curd’s own weight.
After being pressed, the cheese is left for some time (4 - 20 hours) at
20 - 25°C. In the meantime the lactose present in the cheese iscompletely converted into lactic acid. Then the cheese can be salted.
Trying to produce cheese of a Gouda or Edam type in this way will bedisappointing, because the cheese will become very firm, crumbly andacid. The reason for this is that the curd – after fermentation by thelactic acid bacteria - contains too much lactic acid. Therefore Gouda

70

Preparation of dairy products

cheese makers add 15 to 20% of hot water to the curd and whey afterstirring for about 30 minutes. The temperature of the water is such thatafter addition of the water the temperature of the curd and whey is 35– 36°C. (Water temperature is about 65 – 70°C. Before adding the hotwater, part of the whey (30%) is drained off). After adding hot water
the curd-and-whey mixture has to be stirred again for at least 20
minutes.
Salting the cheese
Salting can be done in several ways:
1 Stir the salt through the curd; add 30 grams of salt per kilogram of
curd. This reduces the effect of the bacteria of the starter, but
potentially damaging micro-organisms are also inhibited at an earlystage.
2 After pressing the cheese, rub it in with salt. Rub both sides in andthen turn the cheese. This must be done every day for 3 days; intotal 20 grams of salt is needed per kilogram of cheese.
3 Place the cheese in brine of 200 grams of salt per litre of water at 12- 16°C. During this pickling, the cheese absorbs salt and secretes
lactic acid. The brine becomes more sour and improves in quality; itshould therefore not be thrown away. Salt must be added regularly
to the brine; 20 grams of salt is removed from the brine by eachkilogram of cheese. For a small cheese, e.g. less than 1 kg, picklingtime is about 12 hours. During pickling, the cheese must be turned
once.

7.7

Maturation of the cheese

During the maturation of the cheese, protein and fat are partly broken
down, causing a change in structure and flavour. The older the cheese,the more flavour it will have. Sometimes, after more than one year the
structure becomes crumbly because of the protein breakdown.
Maturation is caused primarily by the enzymes in the cheese. To
mature cheese, it can be stored in a cool room. This is a good method
but technically rather difficult in the tropics. After salting or pickling,cheese is ripened on a wooden shelf in a cool environment (12 - 20°C)

Cheese71

with a not too high relative humidity (about 80%). Cheese must be
turned regularly: initially, i.e. during the first 2 to 3 weeks, daily andlater once a week. If mould grows on the cheese, it can be removed
with water or vinegar.
In addition to this method, the following treatments can be carried out
on curd:? Curd can be smoked over a fire (see figure 25).
? Curd can be boiled in brine.
? You can salt curd, make little balls of it and leave them to dry in thesun.

Figure 25: Smoking curd over a fire

The products which result are particularly suitable to be processed inother foods. After boiling, cheese will not ripen anymore because the
enzymes inside the cheese are destroyed by heating.

72

Preparation of dairy products

7.8

Cheese recipes

There are many variations in cheese making. To
make a good product, it may be necessary to adjust
the recipe. Therefore you should have a good
method of recording exactly how the cheese is made.
Your records can include the following aspects:? date and surrounding temperature? quality of the milk and pasteurisation temperature? amount of milk
? ingredients, amount of starter culture, acid or rennet added? temperature at which starter culture, acid or rennet was added? coagulation time
? temperatures during the cheese making process? temperature at the end of coagulation? pressure applied, length of time applied, etc.
? salting time
? storage time and conditions during storage
The following recipes should be seen as guidelines for making cheese.
Instead of cow milk, you can often use goat, sheep or buffalo milk.
Start by making rather simple products like yoghurt, fresh cheese, etc.
Fresh cheese
Fresh or unripened cheese has a high moisture content of about 75%;
it can be consumed directly after preparation. It is made by removing
the whey from soured, skimmed milk. The milk is usually coagulated
by souring. Sometimes a small amount of rennet is added; this is done
to facilitate the draining of the whey. However, addition of rennet is
not essential.

A well-known kind of fresh cheese is curd, known in various countries
by the following names: Frischkäse, fromage frais, quarg, and baker's
cheese. The differences between these cheeses are their fat levels.

Cheese73

You can make curd by souring fresh milk, cream or skimmed milk
into sour milk, sour cream or sour skimmed milk and then draining the
thick sour milk in a bag or cloth. Sometimes bags are placed on top ofeach other to increase the removal of whey. After draining, the curd
has a crumbly structure. By stirring or using a blender you can makethe product smooth again. There are various kinds of curd cheese inwhich moisture, fat and salt content and size of curd particles vary.
Fresh cheese has a fresh sour taste, especially when it is prepared fromskimmed milk. By adding cream, the taste will become milder andricher.
Curd can be kept for only a short time and must be stored at cooltemperatures. During storage, further whey separation can occur; thisis the result of further souring of the product.
Curd from whole milk
Pasteurise the milk 30 minutes at 63°C and then cool it to 20°C. Add
per 10 litres of milk ¼ - ½ litre of starter culture or fresh sour milk orbuttermilk; yoghurt can be added if desired. Add 2 drops of rennet - ifavailable. It is advisable to dilute this small amount of rennet withseveral ml of water to improve its distribution through the milk.

After stirring well, leave the inoculated milk to stand for 24 hours at
18 – 20°C. During those 24 hours, souring and coagulation will takeplace; the milk becomes a rather firm mass. This thick mass issubsequently poured into a cotton or linen cloth or a bag so that thewhey can drain through the cloth. The cloth is placed into a large
colander or cheese mould beforehand so that the whey can thoroughly
drain. After 24 hours, sufficient whey will have leaked out and theremaining curd can then be mixed, for example with a spoon or
blender, until it becomes a homogenous mass. The curd can now be
consumed. When kept in a refrigerator, curd can be stored for 1 - 2
weeks.

74

Preparation of dairy products

Bag cheese
You will need a sieve, small basket
or cheese mould and a cheesecloth ortea towel.

Let 10 litres of buttermilk with low
fat content drain through acheesecloth until 1.5 litres of bagcheese, or curd, remain. Place acheesecloth in a sieve, small basket Figure 26: Bag cheeseor cheese mould and press the curd
firmly into it. Let the curd drain forseveral hours, then turn it. About 1.5 kg of bag cheese has then been
made, which contains no salt and hardly any fat. It can be kept for
only a rather short time: 1 to 2 weeks. Keep it cool, preferably in arefrigerator.
Krut
For making krut one needs buttermilk, cheesecloth and salt.

This is a way to make cheese from any leftover milk. Add some sour
milk or buttermilk to the leftover milk and mix. Boil the mixture until
the milk curdles. Separate the curd from the whey by pouring it
through a cheesecloth. The curd is then kneaded with 2 - 4% salt anddried in the sun.
Rasagollas
You will need raw milk, a fire, pan, spoon, lemon juice or sour whey,
cheesecloth, bowl, knife and concentrated sugar water.

Rasagollas is a sweet dairy product originally from India.
Traditionally it was formed into sweet curd balls, but because of theway it is prepared here, the curd can only be cut into cubes and notformed into balls.

Cheese75

The milk is boiled with lemon juice (10 tablespoons or 150 ml per 10
litres of milk) or sour whey (1.5 litres per 10 litres of milk) whilestirring continuously. Sour whey can be obtained from drained sour
milk after the production of curd. The curd is separated from the wheyby pouring the mixture into a cheesecloth, which has been placed overa bowl. The slightly elastic curd is cut into cubes with sides of about
2.5 cm. These are then boiled for about an hour in a sugar solution of
600 g per litre of water. 1 litre of sugar solution is needed for eachkilogram of curd. The cubes can be stored quite some time and arevery sweet.
Feta
You will need sheep, goat or cow milk, starter
culture or fresh sour milk, rennet, cooking-salt,
knife, cheese moulds, cheesecloths and cans or aplastic container to store the cheese.

Feta is a sharp, salty cheese originally from Greece that is made of
sheep and goat milk. You can also use a mixture of sheep and cow
milk, but then the cheese will not have its typical white colour. Feta is
kept in a solution of whey and brine.
Heat 10 litres of pasteurised milk mixed with 200 ml of a starter
culture, sour milk or buttermilk to 30°C. After 1 - 2 hours, rennet isadded; use 2 ml of rennet per 10 litres of milk. After allowing it tocoagulate for about one hour, the curd is cut into cubes of about 2.5
cm, after which it is carefully stirred for another 20 minutes.
The curd must then be carefully transferred to the tubs covered withcheesecloth. This can be done either by scooping the curd directly outof the whey into the moulds lined with cheesecloth, or by letting the
curd settle, pouring off the whey and only then putting the curd in thecheese moulds.
After a few hours the cheese must be turned. The curd mass is
carefully removed from the cheesecloth and replaced upside down.

76

Preparation of dairy productsAfter one day, the lumps of curd are cut into cubes of about 10 cm.
Salting can be done by sprinkling the blocks several times with salt orby placing the blocks in brine for 24 hours.
If the cheese is kept for several days at about 18°C, it must be turned
regularly and washed with cold water at the end of the storage period.
The cheese can be kept for some time by piling blocks of cheeseclosely on top of each other and covering them with brine. The cheese
should have a smooth and soft consistency.
Queso blanco
The so-called queso blanco is manufactured in many ways in Latin
America. Typical for this cheese is that salt is added directly to thewhey/curd mixture. This has the advantage that slightly soured milk
can be used to make queso blanco.

A much-used method is the following:
Take raw (unheated) soured milk of 32°C, or take 10 litres ofpasteurised milk and add 50 ml of sour milk, buttermilk or starter
culture. Add 1.5 ml of rennet. After 45 minutes the curd is cut andstirred. Leave the whey/curd mixture to settle for another 30 minutes
at 30 - 36°C. Pour off the whey and compress the curd to remove more
whey. Mix 30 - 50 grams of salt through the curd. The salt can also be
dissolved in water before being added. 100 grams of salt dissolved in
50 ml of water must then be added for each 10 litres of milk.
Transfer the salted curd into cheese moulds and press the cheese.
During the first hours, turn the cheeses occasionally. Press them until
the following day. To improve rind formation, pour whey heated at
50°C over the cheese while being pressed (after one hour). Cheese
made with rennet can be kept for 2 months at 10 - 15°C.
As a variation to this method, you can add acid instead of a starter
culture and use no rennet. Take raw milk, which may already be alittle bit sour. Heat it to almost boiling. Acidify it with 300 ml vinegar
per 10 litres of milk until a precipitate is formed. The acid can be

Cheese77

partly neutralised with the addition of some sodium bicarbonate(double soda). Pour off the whey. Proceed further preparation as
above.
Fresh goat cheese (in oil)
You will need pasteurised goat milk, a heat source, apan with lid, a thermometer, sour milk (or buttermilk
or starter culture), rennet, a spoon, an insulated box
or blanket or newspapers, cheesecloth, salt, cheesemoulds, a cool storage place, greaseproof paper (ifavailable), a large pot, herbs and olive oil.

Bring the pasteurised goat milk to a temperature of 20°C. Per 10 litresof milk, add 0.5 litre of fresh starter or sour milk or buttermilk. Take
20 drops of rennet per litre of milk, dilute this in a little water and stir
this through the milk.
Place the pan in the insulated box or in the blanket or the newspapers
to prevent it from cooling down. Check the next day to see if the milk
has curdled sufficiently; a little whey on top is acceptable.
Cut the curd into cubes the size of a matchbox. After 2 hours transfer
the mass into a cheesecloth and let it drain for 12 hours at room
temperature. Mix the dry curd with some salt and put the cubes into
cheese moulds. Press the curd into the moulds so that no air holes
remain and place the moulds in a cool (15°C) place.
The next day remove the cheese carefully from the cheesecloth andreplace it upside down in the cheesecloth and mould. Leave the cheese
for a further 24 hours in a cool place. Remove the cheeses from clothand mould and turn them daily. Should they become too dry, wrap
them tightly, for example in greaseproof paper. If you wish to store thefresh goat cheese cubes for several weeks, place them in a large(glass) jar, which can be closed. Sprinkle a mixture of different herbs
over them, such as rosemary, basil, thyme, bruised juniper berries, afinely chopped piece of garlic, several pepper kernels and a chopped

78

Preparation of dairy products

up hot pepper. Other herbs can also be used. Pour olive oil over thecheeses until they are just covered and add a few twigs of dill orrosemary to the oil. Close the jar and put it away in a cool and darkplace. Before using the cheeses, let them drain well. Use the leftover
oil for salad dressing.
Fresh goat cheese (salted)
You will need pasteurised goat milk, a heat source, pan with lid,
thermometer, sour milk (or buttermilk or starter culture), acid, spoon,
rennet, knife, colander or cheesecloth, cheese moulds, pressing
equipment and salt.

Heat the pasteurised milk in a pan to 30°C, stirring continuously. For
each 10 litres of milk, add 0.2 - 0.5 litres of sour milk or buttermilk or
0.2 litres of a starter culture and 30 drops of rennet (diluted in water).
After 45 minutes, cut the coagulated curd with a knife; after another10 minutes, the curd will be the size of a marble. The top layer ofwhey can be poured off after leaving the mixture to stand a bit.
Leave the curd in the carefully closed pan with the rest of the whey fora further 30 - 45 minutes. Then transfer the curd into cheese moulds inwhich cheesecloth has been placed. Press the curd; one hour issufficient. The cheeses must then be pickled in brine. For a cheese of
500 grams, 10 hours of pickling is long enough.
Fresh sheep cheese
You will need pasteurised sheep milk, a heat source, a pan, athermometer, a starter culture or fresh sour milk or buttermilk, rennet,
a spoon, a knife, a cheesecloth, some salt (if desired) and cheesemoulds.

Sheep milk contains more fat and protein than cow milk and therefore
only 4 - 4.5 litres of sheep milk are needed to make 1 kg of cheese.
Because of the higher content of dry matter in the milk, sheep milk
coagulates firmer than cow milk.

Cheese79

Heat the pasteurised milk to about 30°C, stirring continuously. Add
300 ml of a starter culture and 40 drops of rennet to each 10 litres ofmilk. After 45 minutes the milk will have coagulated sufficiently to be
cut. Cut the curdled, thick mass carefully; continue till the curdparticles have the size of a pea. Bring the curd into a cheesecloth. If
desired mix in some salt, and let the cloth hang until the cheese has
the desired firmness. You can speed up the draining of the whey by
opening the cheesecloth after several hours, scraping the thick partfrom the cloth, and mixing it in with the rest of the curd.
You may want to make a less sour sheep cheese, which is a little bit
firmer and with some lower moisture content. For this, you must leave
the curd for a longer time: about 15 - 30 minutes in the cheese vat
where the curd treatment is done. After a short period of rest, pour off
part of the whey, stir the curd carefully again and fill the cheese mouldusing a cheesecloth. Add some salt to the curd, if desired. Press the
curd: about 4 hours of light pressing is sufficient. Store in a cool place.
Sheep cheese can be kept for at least one week in the refrigerator.
Matured sheep cheese
You will need pasteurised sheep milk, a heat source, a pan, athermometer, sour milk (buttermilk or starter culture), rennet, a spoon,a knife, colander, a cheesecloth, cheese moulds and pressing
equipment, salt, a tightly sealed pickling tub, coarse cheesecloth and acool storage place.

10 litres of sheep milk yields about 2 kg of ripened cheese. Afteradding 60 ml of starter culture or sour milk (or buttermilk), leave themilk to stand at 30°C for 30 - 45 minutes. Only then add 60 drops ofrennet, diluted with a little water, per 10 litres of milk, and stir it
thoroughly through the milk. After allowing it to curdle for 1 hour, cut
the coagulated milk for about 15 minutes until it is divided into
particles of about 1 - 2 cm. Then stir it for 10 minutes, pour half of thewhey off and heat the curd to 35°C by adding hot water with atemperature of 80-100°C. Stir the mixture again for about 15 minutes,
after which time the curd must be left to stand for 30 minutes in thepan. Keep the pan warm as well as possible but never place it on a
80

Preparation of dairy productsfire. Remove the whey that has separated, and pour the curd with theremaining whey into a colander. After the first draining, the curd mustbe transferred by hand into cheese moulds covered with cheesecloth.
Press the cheese for 15 minutes with its own weight and turn thecheese. Spread the cloth in the mould again, press the cheese in placeand fold the corners of the cloth over it again. Press the cheese for 2 to
3 hours, initially with a weight that is twice that of the cheese, later onwith a weight 3 - 5 times as heavy. Subsequently pickle the cheese inbrine (1 kg for a maximum of 24 hours). Then move it to a cool place
where it must ripen for 5 to 8 weeks.

Cheese81

Further readingBerg, J.C.T.van den. Dairy technology in the tropics and subtropics.
Pudoc Publishers, Wageningen, 1988. ISBN 90-220-0927-0
Berg, J.C.T. van den. Strategy for dairy development in the tropics
and subtropics. Pudoc Publishers, Wageningen, 1990. ISBN 90-2201005-8
French, M.H. Observations on the goat. FAO Rome 1970 (FAO
studies nr 80, FAO Animal production and health series no. 14) ISBN
92-5-100848-5
Kon, S.K. Milk and milk products in human nutrition. FAO
Nutrition Studies no. 27. 1972, Rome.
Kosikowski, F.V. Cheese and fermented milk foods. 1977,
Michigan, USA. ISBN 0-9602322-6-5
Walstra, P. and R. Jenness. Dairy chemistry and Physics. John Wiley& Sons, New York 1984. ISBN 0-471-09779-9
Walstra, P. J.T.M. Wouters and T. J. Geurts. Dairy Science andTechnology. 2nd ed. CRC Press, Taylor & Francis Group, Boca Raton
2006. ISBN 0-8247-2763-082Preparation of dairy products

Useful addresses

PTC+ is an international training institute that focuses on all the links
in the production chain, plant and animal commodities, (agricultural)technology, (food) technology and natural areas.
Training programmes are practice-oriented and mix theory withpractical classes. PTC+ offers open entry programmes, tailor-madeprogrammes and consultancy. Programmes are offered in the
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T+ 31 318 645700
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www.ptcplus.com

FE+ 31 318 595869
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Starter cultures, coagulants

Chr. Hansen
Chr. Hansen develops natural ingredient solutions for dairy industries,
in close cooperation with customers and partners. Customers can
profit from its specialist strategy by receiving quick access to highlevel specialist knowledge, support and customized solutions.
The firm has locations worldwide and its product catalogue isavailable in English, French and Spanish.
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www.chr-hansen.com

Useful addresses

83Protex International / BIOPROX
The following bio-products can be ordered from BIOPROX for the
dairy industry (milk, cheese, butter, yoghurt): lactic culture(mesophilic and/or thermophilic), culture medium, growth factor, pH
corrector, lactic culture activator, cleaning products.
BP 177
F- 92305
Levallois – Paris
FRANCE (also in Morocco, United Kingdom, Portugal and Spain)
T + 33 (0) 1 41 34 14 00
F + 33 (0) 1 41 34 14 16
E
postmaster@protex-international.com
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www.protex-international.com/products/food-flavouring.html
Gebr. RademakerA supplier of cheese making equipment.
Oostzijde 30
1426 AE De Hoef
THE NETHERLANDS
T +31 297 593213
T +31 297 593261
Dairy processing equipment
C. van 't Riet Dairy Technology BV
Dorpsstraat 25
NL- 2445 AJ Aarlanderveen
THE NETHERLANDS
W: www.rietdairy.nl
E: info@rietdairy.nl(Applied) research

Food and Agricultural Organization of the United Nations (FAO)
Viale delle Terme di Caracalla
00100 RomeITALY
E: FAO-HQ@fao.org
W: www.fao.org/ag/AGA/AGAP/LPS/dairy/intro.htm

84

Preparation of dairy products

International Livestock Research Institute (ILRI)
PO Box 30709
NairobiKENYA
W: www.ilri.cgiar.org
E: ILRI-Kenya@cgiar.org
ILRI's mission is to develop animal health and productivity in thepoorest regions of the world through scientific research andmultilateral cooperation.
Intermediate Technology Development Group (ITDG)
Bourton Hall, Bourton on Dunsmore
CV23 9QZ Rugby
Warwickshire, UNITED KINGDOM
E: infoserv@itdg.org.uk
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Technical briefs on Dairy processing and Yoghurt production
E: infoserv@practicalaction.org.uk

Useful addresses

85

Appendix 1: Measures
1 drop20 drops
1 tablespoon
1 cup
1,000 ml86

= 0.05 ml= 1 ml= 15 ml= 250 ml
= 1l

Preparation of dairy products