KENYA STANDARD              DKS 2934 :2021 
ICS 67.100.3 0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Lactose free milk  — Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
© KEBS 20 21          second Edition  2021  DKS 2934 :2021 
 
 
                             KEBS 202 1 — All rights reserved  ii TECHNICAL COMMITTEE REPRESENTATION  
 
The following organizations were represented on the Technical Committee:  
 
Kenya Dairy Board  
Brookside Dairy Limited  
Coca -Cola Company  
Directorate of Veterinary Services, Ministry of Agriculture, Livestock and Fisheries  
Egerton University  
Glacier Products Ltd  
Government Chemist's Department  
Jomo Kenyatt a University of Agriculture and Technology  
Kenya Accreditation Service  
KEVIAN KENYA LTD  
Ministry of Health  
National Public Health Laboratory  
Nestle  
New KCC Ltd.  
Promaco Limited  
Razco Ltd  
Smile Africa Organization  
State Department for Industrialization  
University of Nairobi  
Agriterra  
AMESI[K] LTD  
Brilliant Dairy Farmers Association  
Kenya Bureau of Standards — Secretariat  
 
 
 
 
 
REVISION OF KENYA STANDARDS  
 
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Suggestions for improvement s to published sta ndards , addressed  to the Managing Director, Kenya Bureau of 
Standards , are welcome . 
 
 
 
 
© Kenya Bureau of Standards, 20 20 
 
Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 1 30 of 2001 of  the Laws of Kenya, copyright subsists in 
all Kenya Standards and exc ept as provided under Section 25  of this Act, no Kenya Standard produced by Kenya Bureau of Standards may 
be reproduced, stored in a retrieval system in any form or transmitt ed by any means without prior permission in writing from the Managing 
Director . 
  
KEBS 202 1 — All rights reserved    iii KENYA STANDARD                        
DKS 2934 :2021 
 
ICS 67.100.3 0 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Lactose free milk — Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
KENYA BUREAU OF STANDARDS (KEBS)  
 
Head Office:  P.O. Box 54974, Nairobi -00200, Tel.: (+254 020) 605490, 602350, Fax: (+254 020) 604031  
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Coast Region     Lake Region          Rift Valley Region  
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Fax: (+254 041) 229448    Fax: (+254 057) 21814               
  DKS 2934 :2021 
 
 
                             KEBS 202 1 — All rights reserved  iv Foreword  
 
This Kenya Standard was prep ared by the Milk and Milk Products Technical Committee under the guidance of 
the Standards Project s Committee and it is in accordance with the procedures of the Kenya Bureau of 
Standards.  
 
Lactose is a type  of sugar or carbohydrate in milk and milk product s that can be difficult for some people to 
digest and is normally hydrolyzed during digestion by the enzyme lactase. People deficient in this enzyme can 
experience gastrointestinal symptoms including nausea, cramps, bloating and diarrhea. In commercially 
manufactured lactose -free milk and milk products , most  of the lactose has already been broken down  into 
glucose and galactose which are now well tolerated.  
This Kenya Standard specifies the safety and quality requirements for the Lactose free milk.  
 
 
Durin g the preparation of this standard, reference was made to the following document s: 
 
EAS 27, UHT Milk - Specification  
EAS 69, Pasteurized Milk-Specification  
 
Acknowledgement is hereby made for the assistance derived from these sources.  
 KENYA STANDARD                          DKS 2934 :2021 
 
 
 
   KEBS 202 1 — All rights reser ved    1 
 
 
  
Lactose free milk — Specification  
 
1 Scope  
 
This Draft Kenya  Standard specifies requirements, sampling and test methods for Lactose free  milk.  
 
2 Normative references  
 
The following documents are referred to in the text in such a way that some or all of their content con stitutes 
requirements of this document. For dated references, only the edition cited applies. For undated references, the 
latest edition of the referenced document (including any amendments) applies.  
 
AOAC Method 984.15. Enzymatic hydrolysis of lactose to  glucose and galactose at pH 6.6 by β -galactosidase.  
AOAC 999.10, Official method for lead, cadmium, zinc, copper, and iron in foods Atomic Absorption  
Spectrophotometry after microwave Digestion  
KS EAS, UHT Milk - Specification  
KS EAS 39, General principle s for food hygiene  
KS 1552, Code of hygienic practice for milk and milk products  
KS EAS 38, Labelling of pre - packaged foods — General requirements  
KS EAS 803, Nutrition labelling — Requirements  
KS ISO 707, Milk and milk products — Guidance on sampling   
KS ISO 2446, Milk — Determination of fat content  
KS ISO 4832, Microbiology of food and animal feeding stuffs — Horizontal method for the enumeration of 
coliforms — Colony count technique  
KS ISO 4833 -1, Microbiology of the food chain — Horizontal method  for the enumeration of microorganisms — 
Part 1: Colony count at 30 degrees C by the pour plate technique  
KS ISO 5764, Milk — determination of freezing point — Thermistor cryoscope method (Reference method)  
KS ISO 6579 -1, Microbiology of the food chain — Horizontal method for the detection, enumeration and 
serotyping of Salmonella — Part 1: Detection of Salmonella spp  
KS ISO 6731, Milk, cream and evaporated milk — Determination of total solids content (Reference method)  
KS ISO 6888 -3, Microbiology of fo od and animal feeding stuffs — Horizontal method for the enumeration of 
coagulase -positive staphylococci (Staphylococcus aureus and other species) — Part 3: Detection and MPN 
technique for low numbers  
KS ISO 8968 -4, Milk and milk products — Determination of nitrogen content — Part 4: Determination of protein 
and non -protein nitrogen content and true protein content calculation (Reference method)  
KS ISO 14501, Milk and milk powder — Determination of aflatoxin M1 content — Clean -up by immunoaffinity 
chromat ography and determination by high -performance liquid chromatography  
KS ISO 22662, Milk and milk products — Determination of lactose content by high -performance liquid 
chromatography (Reference method)  
 
3 Terms and definitions  
 
For the purposes of this do cument, the following terms and definitions apply.  
 
3.1 pasteurized milk  
milk which has been subjected to pasteurization either by batch method, flash pasteurization or High 
Temperature Short Time method (HTST)   DKS 2934 :2021 
 
 
 
 
2     KEBS 202 1 — All rights reserved  
 
 3.2 homogenization  process by which milk f at globules are finely divided and interspersed to form a 
homogeneous product so as to prevent the fat from floating on the surface and adhering to the inside of the 
container  
 
3.3 UHT milk  
milk that is treated under ultra -high temperatures (at 135° – 150° centigrade for 2 secs - 6 sec), homogenized, 
filled and sealed aseptically into sterile retail containers in order to maintain commercial sterility under room 
temperatures  
 
3.4 commercial sterility  
condition achieved by application of heat sufficient, alone or in combination with other appropriate treatment to 
render food free from microorganisms capable of growing in the food as normal non -refrigerated conditions at 
which the food is likely to held during distribution and storage  
 
3.5 reconstituted mi lk 
 product resulting from the addition of water to the dried or concentrated form of the product in the amount 
necessary to re -establish the appropriate water to solids ratio.  
 
3.6 recombined milk  
product resulting from the combining of milkfat and milk -solids -non-fat in their preserved forms with or without 
the addition of water to achieve the appropriate milk product composition.  
 
3.7 toned milk  
 product prepared by a mixture of cow milk with skimmed milk or powdered milk in the amount necessary to 
reestablish the appropriate milk product composition.  
Lactose free milk  
shall mean the product prepared from any type of milk specified in section 4. (1) below, in which, lactose content 
has been reduced significantly through hydrolysis by enzymatic or any other appropriate process.  
 
4 Requirements  
 
4.1 Raw materials  
 
Raw materials for Lactose free  milk may include:  
UHT milk;  
reconstituted milk;  
recombined milk;  
pasteurized milk; or  
toned milk  
lactose free milk powder  
 
4.2 General requirements  
 
Lactose  free milk shall:  
a) be processed without affecting the composition of the product;  
b) have characteristic of texture and colour  
c) be free from preservatives, off -flavours and odour ; and  
d) free from objectionable tastes and f oreign Matter  
         
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 4.3 Specif ic requirements  
 
Lactose free  milk shall comply with the specific  requirements given in Table 1 when tested in accordance with 
tests methods specified therein.  
 
Table 1 — Specific requirements for Lactose free  milk  
 
S/N  Characteristic   Requirement  Test method  
 Lactose content (%), m/m  
 have less than 1% lactose  
 KS ISO 22662 /  
AOAC Method 984.15  
i.   pH  4.0 – 8.5  Annex A  
ii.   Titratable acidity, % lactic 
acid, max.  0.02 Annex B  
iii.    Density at 20 °C g/ml,  1.028 - 1.036  Annex C  
iv. Milk fat  (%), m/m   
 
 
KS SO 2446   a) Whole milk/full cream 
milk, min.  3.25  
 b) Fat reduced milk/semi 
skimmed  1.51 - 3.24  
 c) Low fat milk/skimmed 
milk  0.51 - 1.50  
 d) Fat free milk, max.  0.50  
v.    Milk Solids Non -Fat, %, 
min.  8.5  KS ISO 67 31  
vi.   Protein content, %, min.  3  KS ISO 8968 -4  
vii.   Freezing point, °C  -0.550 to -0.525 I  KS ISO 5764  
 
5 Hygiene  
 
5.1 Lactose free milk shall be produced and handled in accordance with KS 1552 and KS EAS 39.  
 
5.2 Lactose free milk shall comp ly with microbiological limits given in Table 2 when tested in accordance 
with the test methods specified therein.  
 
 
Table 2 — Microbiological requirements for Lactose free milk  
 
S/N   Micro -organisms  Maximum limits  Test method  
i. Total plate count, C FU/ ml  10  KS ISO 4833 -  
ii.   Coliform, CFU/ ml  absent  KS  ISO 4832  
iii.   iii.  Staphylococcus 
aureus (coagulase 
positive), CFU/ ml  absent  KS ISO 6888 -3 
iv.   
  
 Salmonella spp, per 25 ml  Absent  
  
 KS ISO  6579 -1  
  
 
 
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6 Contaminants  
 
6.1 Pesti cide residues  
 
Lactose free milk shall comply with maximum limits residues set by Codex Alimentarius Commission.  
 
6.2 veterinary drug residues  
 
Lactose free milk  shall comply with the maximum residue limits set by the Codex Alimentarius Commission.  
 
6.3 Heavy Metal  
 
When tested in accordance with AOAC 999.10, the level of Lead (Pb) shall not exceed 0.02 mg/kg  
 
6.4 Mycotoxins  
 
When tested in accordance with ISO 14501, the level of aflatoxin M1 shall not exceed 0.50 µg/kg.  
 
 
8 Packaging  
 
8.1 The packaging mat erial used for lactose free  milk shall be food grade and shall:  
 
a) be lightproof;  
b) be gas -proof;  
c) be mechanically strong;  
d) be non -toxic;  
e) not impart any off -flavour to the milk;  
f) be able to withstand aseptic packaging pre -treatment procedure; an d 
g) allow hermetic sealing.  
 
8.2 The lactose free milk shall be packaged aseptically into sterile packaging material.  
 
  
8.3 The Lactose free  milk packages shall not be deformed, creased, dented or have crushed corners.  
 
 
9 Labelling  
 
The containers shall  be labelled in compliance with the requirements of KS EAS 38 and KS EAS 803. In 
addition, the following particulars shall be legibly and indelibly labelled on the container:  
a)  
 
b) fat content; categories as either:  
(i) whole milk/full cream milk;  
(ii) fat reduced milk/semi skimmed milk/low fat milk; or          
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 (iii) fat free milk/skimmed milk  
 
c) net content in SI units;  
d) name and physical address of manufacturer;  
e) batch or code number;  
f) the fat content;  
g) nutritional information;  
h) the date of manufac ture and expiry date;  
i) instruction for storage and use; and  
j) country of origin;  
 
9 Sampling  
Sampling for Lactose milk shall be done in accordance with KS ISO 707.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Annex A (normative)  
  
Determination of p H variation  
A.1 Apparatus  
A.1.1 Incubator adjusted at 55 °C ± 1 °C  
A.1.2 pH meter  
A.2 Procedure  
A.2.1 Determine the pH of 50 ml of the sample in the flask, with a glass electrode at 20 °C and note reading. 
Then incubate another 50 ml of the sample at 55 °C ± 1 °C for five days. Examine the flask each day, then 
shake and replace it in the incubator. If any physical alteration of the contents is observed (coagulation with, or 
without exudation, grittiness, flocculation, formation of bubbles or scum pepto nization or proteolysis) the result of 
the test shall be considered positive and the sample as nonsterile.  
A.2.2 If no alteration takes place during the five days’  incubation at 55 °C ± 1 °C remove the sample from the 
incubator and cool to room temperatur e. Take a small portion of it and measure the pH in the pH meter with 
glass electrode at 20 °C. From this pH value subtract the initial pH value (A.2.1).  
A.3 Interpretation of results  
A sample which does not show any physical alteration during incubation  at 55 °C ± 1 °C for five days and where 
the pH does not show a difference of more than 0.3 unit from the initial pH is considered sterile.  
 
 
 
Annex B (normative)  
  
Determination of titratable acidity  
B.1 Apparatus  
B.1.1 Incubator  
B.1.2 Burette; with s oda-lime guard tube  
B.1.3 Porcelain dishes; white hemispherical of approximately 60 ml  
B.1.4 Stirring rods; of glass, flattened at one end  
B.2 Reagents  
B.2.1 Standard sodium hydroxide solution  
Prepare concentrated stock solution of sodium hydroxide by  dissolving equal parts of sodium hydroxide (stocks 
or pellets) in equal parts of water in a flask. Tightly stopper the flask with a rubber bung and allow any insoluble 
sodium carbonate to settle down for three to four days.  
Use the clear supernatant liqu id for preparing the standard 0.1 M solution. About 8 ml of stock solution is 
required per litre of distilled water. The solution should be accurately standardized against acidic potassium 
phthalate or oxalic acid.  
B.2.2 Phenolphthalein indicator solution   
Dissolve 1 g of phenolphthalein in 110 ml rectified spirit. Add 0.1 M sodium hydroxide solution until one drop 
gives a faint pink coloration.  
B.2.3 Rosaniline Acetate Stock Solution          
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 Dissolve 0.121 g of rosaniline acetate in approximately 50 ml of recti fied spirit, containing 0.5 ml of facial acetic 
acid. Make up to 100 ml with rectified spirit.  
B.2.4 Bench solution  
Dilute 1 ml of stock solution to 500 ml with a mixture of rectified spirit and distilled water in equal proportions by 
volume.  
The stock and the bench solutions shall be stored in dark brown bottles securely stoppered with rubber bungs.  
B.3 Procedure  
B.3.1 Acidity of fresh sample  
Weigh 10.0 g of the sample into each of the two white porcelain dishes of approximately 60 ml capacity; add t o 
both 10 ml of water and stir to disperse the sample. Prepare from one dilution a colour control by adding and 
stirring 2 ml dilute rosaniline acetate solution. Stir 2 ml phenolphthalein solution into the other dilution and while 
stirring vigorously, add a s rapidly as possible sodium hydroxide solution from a 10 -ml burette fitted with a soda -
lime guard tube, until the colour matches the pink colour of the control. The titration shall be done in bright light.  
B.3.2 Acidity after incubation  
Incubate another  20 g of sample at 55 °C ± 1 °C for five days. Examine the flask each day, then shake and 
replace it in the incubator. If any physical alteration of the content is observed the results of the test shall be 
considered positive and the sample as non -sterile.   
If no alteration takes place during the five days’  incubation remove the sample from the incubator and cool to 
room temperature. Weigh 10 g of the incubated sample and determine acidity as described in B.3.1.  
B.4 Calculation  
B.4.1 Acidity of fresh samp le  
Titratable acidity (as lactic acid) per cent by weight =  
m MV .9 /w 
  
Where,  
V=is the volume in ml of the standard sodium hydroxide required for titration (see B.3.1)  
M=is the molarity of the standard sodium hydroxide solution (see B.3), and  
m=is th e mass in g of the sample taken for test (see B.3.1).  
B.4.2 Acidity after incubation  
B.4.2.1 Titratable acidity (as lactic acid) percent by weight =  
MV .9 /w 
  
Where,  
V=is the volume in ml of the standard sodium hydroxide required for titration (see B.2 .1),  
M=is the molarity of the standard sodium hydroxide solution (see B.2.1),  
w=is the weight in g of the sample taken for the test (see B.2.1)  
B.4.2.2 Subtract the value obtained in B.4.1 from the value obtained in B.4.2 which would give increase in 
acidity.  
B.5 Interpretation of results  
A sample which does not show any physical alteration during incubation at 55 °C ± 1 °C for five days and where 
the acidity does not show a difference of more than 0.02 g from the initial acidity is considered sterile.  
 
Annex C (normative)  
  
Determination of Density in milk  
C.1 General  
The density is a relationship between the body mass and the volume this body occupies in the space. The 
density test is performed in order to be used in the detection of adulteration i n the milk since, the addition of 
water only would cause the decrease in density, whereas the skimming (fat removal) would cause an increased 
density in the milk, beside supplying important information for the determination of the total dry extract.   DKS 2934 :2021 
 
 
 
 
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 C.2 E quipment  
The following equipment shall be used:  
a) Thermolactodensimeter (TLD); and  
b) Test tube (250 mL)  
C.3 Methods  
The density determination is accomplished by the Thermolactodensimeter because the practicability of this 
method.  
C.4 Procedure  
C.4.1 Place the sample to be analyzed in the clean and dry test tube by taking the care of inclining the test tube 
and allowing the liquid to flow down the walls of the glass for avoiding the incorporation of the air which would 
reduce the density of the milk .  
C.4.2 Immense TLD into the test tube and make it rotate slowly on its own axis.  
C.4.3 Perform the reading of both density and temperature of the milk as soon as TLD stabilizes.  
C.4.4 Proceed to the correction of the influence from the temperature, by using an adequate scale. The result 
will correspond to the corrected milk density.