Natural cheese of intensified flavor

The present invention is directed to a natural cheese product having a highly intensified American cheese flavor and to a method for preparing such cheese product. The cheese product is adapted for use as a cheese flavoring ingredient in cooked products, for example, process cheese. In the method, curd particles are produced, mixed with salt, a source of a lipolytic enzyme, and a source of a proteolytic enzyme, and cured for a period of time sufficient to produce increased levels of C.sub.2 -C.sub.10 fatty acids as compared to conventional American-type cheese.

The present invention relates generally to a natural cheese product having 
a highly intensified cheese flavor and to a method for manufacturing such 
cheese product. More particularly, the present invention is directed to a 
natural cheese product having an intensified American cheese flavor which 
is useful in the manufacture of process cheese and other cheese products 
or cheese-containing products wherein a high level of cheese flavor is 
desirable. American cheese and American-type cheese are descriptive terms 
used to identify a group of cheeses which includes Cheddar cheese, Colby 
cheese, Monterey cheese, Jack cheese, and stirred-curd, washed-curd, and 
soaked-curd Cheddar type cheese, all of which have a generally similar 
American cheese flavor. The cheese product of the present invention has an 
American cheese flavor, but the flavor is of such intensity that it would 
not generally be considered palatable when consumed alone. However, when 
added to cooked cheese-containing products, such as process cheese and 
baked goods, in relatively small amounts it imparts an American-type 
cheese flavor to such product, and therefore may replace all or a part of 
the aged American cheese normally added to such products as a flavoring 
ingredient. 
The intensely flavored cheese product of the present invention is 
particularly useful as a flavoring ingredient in the manufacture of 
process cheese, cheese foods, and/or cheese spread. The term "process 
cheese" refers to cheese which is made by grinding and mixing together, 
with heating and stirring, one or more natural cheeses of the same or two 
or more varieties. An emulsifying agent is added to the mixture, and the 
mixture is worked into a homogeneous, plastic mass. Various acids may be 
added, such as lactic acid, citric acid, acetic acid, phosphoric acid, or 
vinegar. The moisture level of process cheese generally does not exceed 
about 40 percent, and process cheese has a minimum fat level of about 50 
percent on a dry basis. 
The term "cheese food" refers to a cheese product which is prepared 
generally from the same materials and the same process indicated above for 
process cheese. However, cheese food may have optional diary ingredients 
added thereto, such as cream, milk, skim milk, whey, or any of these from 
which part of the water has been removed. The moisture level of cheese 
food is generally higher than that of process cheese, and may be up to 
about 44 percent. The fat is at least about 23 percent, but is usually 
less than 50 percent. 
The term "cheese spread" refers to a cheese product which is generally 
similar to cheese food products but may have a moisture level of up to 60 
percent. The minimum fat level for cheese spread is about 20 percent. 
The term "process cheese" is sometimes used generically to refer to any of 
the various types of cheese products which are made by grinding various 
types of natural cheese and mixing such ground cheese with added 
emulsifier and heating until a uniform plastic cheese mass is obtained. As 
used herein, the term "process cheese" is intended to include cheese 
spread and cheese foods and also powdered cheese products made by spray 
drying process cheese in accordance with well known practices. 
It is the usual practice in the manufacture of process cheese to use a 
combination of cheeses including an aged cheese for flavor, a "short-held" 
cheese having a minimal cheese flavor, and a green curd which is unaged or 
uncured and has no flavor. The aged cheese is usually an American-type 
cheese, e.g., Cheddar cheese, but may be another natural aged cheese, such 
as Swiss cheese. 
The production of aged Cheddar cheese requires many months of curing to 
develop the level of flavor normally associated with aged Cheddar cheese. 
As used herein, the term "highly flavored cheese product" or "cheese 
product having an intensified American cheese flavor" refers to a natural 
cheese product which has a flavor level that is significantly greater than 
that normally associated with conventional aged American cheese. Such 
highly flavored cheese product may or may not have suitable flavor 
characteristics for direct eating. Usually, the highly flavored cheese 
product is used as a flavoring component in cheese or other food products, 
and, more particularly, in products which are cooked, as described in 
detail hereinafter. 
Various attempts have been made to reduce the curing time required to 
produce American cheese having a desired aged cheese flavor and together 
with acceptable body and texture. To accomplish this result, the make 
procedure and/or curing temperature conventionally employed has been 
altered. An example of one such process is described in U.S. Pat. No. 
3,175,915. In addition to developing the characteristic flavor of aged 
cheese, such products must also have the texture, body, aroma, and mouth 
feel normally associated with aged cheese. 
Another area of development with respect to cheese flavor is that of the 
addition of various chemicals and/or enzymes to the milk prior to setting 
or to the curd after separation of whey. Addition of particular enzymes to 
the milk is disclosed in U.S. Pat. No. 3,650,768 for the purpose of 
increasing flavor development when heat-treated milk is utilized. Other 
examples of prior art processes utilizing enzymes are set forth in U.S. 
Pat. Nos. 3,295,991 and 2,531,329. These processes also produce flavor and 
other characteristics generally similar to aged natural cheese. 
Cheese flavoring products intended for use as flavoring ingredients have 
also been developed as exemplified by U.S. Pat. Nos. 3,840,672 and 
3,729,326. These products, generally in powder form, are intended to be 
used as flavoring ingredients and are not consumed directly. 
It would be desirable to provide a natural cheese product having an 
intensified American cheese flavor. It would be particularly desirable to 
provide a method for the manufacture of such a cheese product with an 
intensified American cheese flavor in a relatively short curing time, 
i.e., in less than about three months. 
Accordingly, it is a principal object of the present invention to provide a 
natural cheese product having an intensified American cheese flavor and a 
method of manufacturing such cheese product. It is another object of the 
present invention to provide a method for the manufacture of a natural 
cheese product having an intensified American cheese flavor in a reduced 
period of time. It is a further object to provide a method for the 
manufacture of process cheese utilizing a natural cheese product of 
intensified American cheese flavor.

Generally, the present invention is directed to a natural cheese product 
having increased levels of C.sub.2 -C.sub.10 fatty acids and an 
intensified American cheese flavor as compared to conventional aged 
natural American cheese. 
More particularly, the present invention relates to an American-type cheese 
product having a C.sub.2 -C.sub.10 fatty acid content at least about ten 
times the C.sub.2 -C.sub.10 fatty acid content of conventional aged 
American-type cheese. 
The present invention further relates to a method of manufacturing a 
natural American-type cheese product of intensified American cheese flavor 
which includes providing a mixture of curd particles and whey by any one 
of a number of known American-type cheese make procedures, separating the 
whey from the curd, adding salt, a source of a proteolytic enzyme, and a 
source of a lipolytic enzyme to the curd, and curing the curd at a 
temperature above about 50.degree. F. for a period of time sufficient to 
provide a C.sub.2 -C.sub.10 fatty acid content at least about ten times as 
great as the C.sub.2 -C.sub.10 fatty acid content of conventional aged 
natural American-type cheese. When expressed as percentage of fatty acids 
in the cheese, American-type cheese produced by the present invention has 
a total free C.sub.2 -C.sub.10 fatty acid content of at least about 0.46 
percent and a free C.sub.4 fatty acid content of at least about 0.32 
percent by weight. 
A proteolytic micrococcus and a flavor culture, as described hereinafter, 
may also be added to the curd with the proteolytic enzyme and the 
lipolytic enzyme to provide a natural cheese product which, when used as a 
flavoring ingredient in cooked cheese-containing products, provides a more 
rounded and fuller American-type cheese flavored product. It has also been 
found desirable, particularly when the cheese product of the invention is 
utilized in the manufacture of process cheese, to prepare the cheese curd 
using a make procedure as described in U.S. Pat. No. 3,650,768 in which a 
proteolytic micrococcus, a self-limiting lipase, and a flavor culture are 
added to the milk prior to setting of the milk. 
The preferred medium for preparing the highly flavored cheese product of 
the present invention is whole cow's milk having about 3 percent protein 
which is principally casein, about 5 percent lactose, about 1 percent ash, 
and about 3.5 percent fat. The milk may be partially or wholly skimmed, 
and other fats may be used to replace or supplement a portion of the milk 
fat of the whole milk. In this connection, preferred fats for replacement 
of milk fat are coconut fat, soybean oil, cottonseed oil, peanut oil, 
safflower oil, and mixtures thereof. Other protein sources may also be 
used in combination with the casein of the whole milk. In this connection, 
up to about 50 percent of the casein may be replaced with protein sources 
such as soy protein, yeast protein, fish meal protein, whey protein, and 
mixtures thereof. 
The preferred method for preparing curd particles to which the enzymes and 
cultures of the present invention are applied is known and is usually 
referred to as the stirred curd method. In this method, a lactic acid 
producing culture, preferably S. lactis, is added to the medium. The 
medium is set with single strength calves rennet at a level of about 100 
cc's of rennet per 1000 pounds milk. A setting period of thirty minutes is 
allowed after addition of the rennet for coagulation of the medium. The 
coagulum is cut with quarter-inch knives to provide curd particles and 
whey when the titratable acidity of the coagulum is about 0.11 to about 
0.12 equivalent lactic acid, and the pH of the whey is about 6.4 as 
measured by the quinhydrone method. As set forth herein, all reference to 
titratable acidity refers to equivalent lactic acid, and all pH values are 
measured by the quinhydrone method. After cutting, the curd particles are 
stirred in the whey and the curd particles are then heated over a period 
of thirty minutes to a temperature of about 103.degree. F. to cook the 
curd. The curd is held while being stirred in the whey at 103.degree. F. 
until the titratable acidity of the whey is about 0.17 and the curd has a 
pH of about 5.8, a period of about sixty minutes. The curd and whey 
mixture is then pumped to a drain table while the temperature of 
103.degree. F. is maintained. The whey is drawn from the curd until the 
level of whey is slightly higher than the level of the curd. The curd is 
stirred in the whey for a period of about sixty minutes or until the 
titratable acidity of the whey is about 0.28 and then the whey is allowed 
to freely drain from the curd. The curd at this time has a pH of about 
5.36. 
After a period of about fifteen minutes of free whey drainage, the curd is 
salted with sodium chloride at a level of about 2.0 pounds of salt per 
1000 pounds of medium used to prepare the curd and a source of a lipolytic 
enzyme, i.e., a lipase, and a source of a proteolytic enzyme, i.e., a 
protease, are added to the curd. The preferred source of lipase is that 
obtained by extraction from the throat tissue of calves, lambs, or kids. 
These lipases are commercially available under the trade names Italase C 
and Capalase KL and their manufacture is generally disclosed in U.S. Pat. 
Nos. 2,531,329 and 2,794,743. These particular lipases are self-limiting 
in the hydrolysis of fat and do not break down the fat to undesired end 
products. Such lipases are sometimes referred to herein as "self-limiting 
lipases" to denote their restricted activity in the hydrolysis of fat. 
Other forms of lipolytic enzymes, such as microbial lipases and pancreatic 
lipases, may be substituted for all or a part of the throat tissue 
lipases. An example of a commercially available microbial lipase is that 
obtained from Candida cylindracea, Type VIII. An example of a commercially 
available pancreatic lipase is that sold as porcine pancreatic lipase. One 
unit of the C. cylindracea microbial lipase will hydrolyze 1.0 
microequivalent of fatty acid from a triglyceride in one hour at pH 7.4 at 
37.degree. C. One unit of the porcine pancreatic lipase will release 1.0 
micromole of acid per minute at pH 8.0 at 25.degree. C. from an olive oil 
substrate. 
The results of a comparison of throat tissue lipase, microbial lipase, and 
pancreatic lipase are set forth in Table I. The respective samples were 
incubated in 36 percent butterfat Grade A whipping cream, fatty acids were 
removed by steam distillation, and fatty acid analysis was by gas 
chromatography. A control sample, with no addition of lipase, was 
incubated at room temperature for four and one-half hours. 
TABLE I 
______________________________________ 
Weight % Free Fatty Acid 
Sample C.sub.2 C.sub.4 C.sub.6 
C.sub.8 
C.sub.10 
C.sub.12 
______________________________________ 
Control -- 0.001 0.001 0.001 0.002 0.001 
P-10.sup.1 
-- 0.078 0.036 0.022 0.022 0.008 
P-50.sup.2 
-- 0.180 0.086 0.051 0.074 0.042 
M-200.sup.3 
-- 0.461 0.169 0.153 0.207 0.059 
C-200.sup.4 
0.003 0.061 0.018 0.009 0.016 -- 
K-200.sup.5 
0.004 0.076 0.033 0.010 0.009 -- 
KL-200.sup.6 
0.002 0.087 0.037 0.011 0.017 -- 
______________________________________ 
.sup.1 10 mg. porcine pancreatic lipase per 100 gm. cream incubated at 
room temperature 30 hours. 
.sup.2 Same as .sup.1 except 50 mg. lipase per 100 gm. cream. 
.sup.3 200 mg. C. cylindracea Candida microbial lipase per 100 gm. cream 
incubated at room temperature for 30 hours. 
.sup.4 200 mg. Italase C calf tissue lipase per 100 gm. cream incubated 
41/2 hours at room temperature. 
.sup.5 200 mg. Capalase K kid tissue lipase per 100 gm. cream incubated 
41/2 hours at room temperature. 
.sup. 6 200 mg. Capalase KL mixed kid and lamb tissue lipase per 100 gm. 
cream incubated 41/2 hours at room temperature. 
From the foregoing it can be seen that various sources of lipase may be 
utilized in the present invention, although suitable adjustments, within 
the skill of the art, may have to be made in concentration, curing 
temperature, and the like. For best results, however, the use of a 
combination of the self-limiting calf, kid, and lamb throat tissue lipases 
is preferred, and the examples and discussion herein are limited to their 
use. 
The source of proteolytic enzyme may be selected from any one of a number 
of available materials which yield a protease enzyme having a high 
proteolytic activity. The type of protease and its manner of use act to 
enhance breakdown of the protein in the curd and to minimize formation of 
bitter peptides. Further, the protease causes complete breakdown of at 
least a portion of the protein to amino acids which is considered to be 
desirable to provide a more complete flavor profile in the finished 
product. 
The source of protease may be added to the curd separately from the source 
of lipase, or, in some instances, the source of lipase may naturally 
contain sufficient quantities of proteases having the desired high 
proteolytic activity that an additional source of protease need not be 
added to the curd. In this connection, throat tissue lipases sold under 
the trade names Italase and Capalase have been found to contain sufficient 
protease that when a relatively high level of lipase is added to the curd 
no additional source of protease is required. 
However, for most purposes, and to provide a desired flavor profile, 
particularly where the cheese product is to be incorporated in process 
cheese, a separate source of proteolytic enzyme is added to the curd in 
addition to that which may be present in the source of lipolytic enzyme. 
Examples of suitable proteolytic enzymes are those derived from plant 
sources, such as papain, and from microorganisms, such as those sold under 
the trade names Rhozyme P-11, Rhozyme P-53, and Rhozyme P-54 obtained from 
A. flavus oryzae and B. subtilis, and mixtures thereof. 
The present invention contemplates that other proteolytic enzymes or 
proteases might also be used in the present invention. Selection of such 
proteolytic enzymes is considered to be within the skill of the art based 
upon known microbiological screening techniques. Regardless of the source 
of proteolytic enzyme, it should have a good proteolytic activity in a 
milk source under cheese making conditions and should not produce protein 
byproducts which impart bitter flavor to the cheese product. 
In accordance with the present invention, it has been discovered that a 
highly intensified American-type cheese flavor can be imparted to a 
natural American-type cheese product by substantially increasing the 
C.sub.2 -C.sub.10 fatty acid content of the cheese. This is in marked 
contrast to the fatty acid content of conventional aged American cheese, 
e.g. Cheddar cheese, which is very low and does not markedly change during 
the curing cycle. There is set forth in Table II the weight percent of the 
C.sub.2 -C.sub.10 fatty acids of conventional Cheddar cheese at various 
ages. 
TABLE II 
__________________________________________________________________________ 
Weight % Free Fatty Acid 
No. 
Sample Age C.sub.2 
C.sub.4 
C.sub.6 
C.sub.8 
C.sub.10 
__________________________________________________________________________ 
1 4-15-C: Cheddar cheese 
mfd pursuant to U.S. 
Pat. No. 3,650,768 
1 day 
0.008 
0.001 
-- 0.001 
0.001 
2 Same as No. 1 
28 days 
0.010 
0.016 
0.004 
0.002 
0.008 
3 New York Sharp Cheddar 
mfd pursuant to U.S. 
Pat. No. 3,650,768 
7 mos. 
0.011 
0.014 
0.004 
0.002 
0.003 
4 Wisconsin Natural 
Cheddar cheese 
7 mos. 
0.026 
0.006 
0.003 
0.002 
0.004 
5 5-2-1-1 Sharp Cheddar 
cheese 6 mos. 
0.050 
0.007 
0.003 
0.002 
0.007 
__________________________________________________________________________ 
It can be seen from Table II that there is no appreciable free C.sub.2 
-C.sub.10 fatty acids present in conventional Cheddar cheese throughout 
its curing cycle. The average fatty acid content of Samples 2, 3, 4, and 5 
appear as the lower curve in FIG. 1. 
The natural cheese products of intensified flavor of the present invention 
have a substantially increased free fatty acid content as compared to the 
conventional aged Cheddar cheeses set forth in Table II. There is set 
forth in Table III the weight percent of the C.sub.2 -C.sub.10 fatty acids 
of production size quantities of a preferred cheese having an intensified 
flavor manufactured in accord with the present invention in which the milk 
is inoculated with a proteolytic micrococcus and a self-limiting lipase, 
and a proteolytic micrococcus and flavoring microorganism are added to the 
curd in addition to the lipolytic enzyme and proteolytic enzyme. 
TABLE III 
______________________________________ 
Weight % Free Fatty Acid 
No. Age C.sub.2 C.sub.4 
C.sub.6 
C.sub.8 
C.sub.10 
______________________________________ 
6 115 days 0.151 0.403 0.137 0.048 0.102 
7 105 days 0.184 0.349 0.120 0.044 0.079 
8 unknown 0.170 0.490 0.152 0.051 0.103 
______________________________________ 
The free fatty acid distribution curves of Samples 6, 7, and 8, as well as 
the average free fatty acids of conventional Cheddar cheese samples 2, 3, 
4, and 5 are plotted in FIG. 1. It is readily apparent that the free fatty 
acid content of the natural cheese of the present invention greatly 
exceeds that of conventional American-type cheese. In this connection, it 
is believed that the C.sub.2 fatty acid content is not as important as the 
C.sub.4 -C.sub.10 fatty acid content. The marked increase in the C.sub.4 
fatty acid, as compared to the C.sub.6, C.sub.8, and C.sub.10 fatty acids 
in Samples 6, 7, and 8, as compared to Samples 2, 3, 4, and 5, is believed 
to be important to the provision of an intensified American-type cheese 
flavor in the cheese products of the present invention. 
FIG. 1 demonstrates that the preferred natural cheese products of the 
present invention have a C.sub.2 -C.sub.10 fatty acid content at least 
about twenty to thirty times as great as the free fatty acid content of 
conventional aged American-type cheese. As the increased amounts of free 
fatty acids decrease, the intensity of flavor of the cheese product 
decreases. Accordingly, in order to provide a sufficient intensity of 
flavor in the cheese product, the C.sub.2 -C.sub.10 free fatty acid 
content of the cheese product of the present invention should be no less 
than ten times the free fatty acid content of conventional American-type 
cheese. 
In addition to the foregoing, it is believed that the drastically increased 
C.sub.4 fatty acid content of the cheese product of the present invention 
is at least partially responsible for the intensified American-type cheese 
flavor that is obtained. Referring to FIG. 1, it will be seen that the 
average C.sub.4 fatty acid content of production lots in accordance with 
the preferred embodiment of the invention is at least about thirty times 
the C.sub.4 fatty acid content of the average of Samples 2, 3, 4, and 5. 
Sample 7, having the lowest C.sub.4 fatty acid content of the production 
samples, has a C.sub.4 fatty acid content in excess of ten times the 
C.sub.4 fatty acid content of Sample 4, which has the maximum C.sub.4 
fatty acid content of the conventional aged Cheddar cheeses set forth in 
Table I. 
It is to be understood that the amount of free fatty acid in cheese varies 
from lot to lot depending on milk source, enzyme source, and the like. It 
is therefore difficult to state precisely the free fatty acid content that 
is necessary to obtain the benefits of the present invention with 
particularity. It is known, however, that the addition of a source of 
lipase and a source of protease in accordance with the present invention 
provides a cheese product of intensified flavor which has a greatly 
increased free fatty acid content. It is believed, based upon present 
knowledge, that this increase should be in excess of ten times. However, 
the addition of lipase and protease which do not attain a tenfold fatty 
acid increase but yet provide an intensified flavor level equivalent to 
that described herein are considered to be within the spirit of the 
present invention. 
In a preferred embodiment of the invention, a proteolytic micrococcus 
culture is used in combination with the source of lipase and source of 
protease. The proteolytic micrococcus appears to act with the lipase and 
protease to provide a controlled level of peptide formation which 
contributes to the intensified American-type cheese flavor of the cheese 
product of the invention. The proteolytic micrococcus is a particular 
microorganism which provides controlled protein breakdown during curing of 
the cheese. The preferred proteolytic micrococcus for this invention is a 
Micrococcus Cohn selected from subgroups 1 to 4 inclusive. A particularly 
preferred proteolytic micrococcus is a Micrococcus Cohn subgroup 2. The 
classification of Micrococcus Cohn and the manner of determination of the 
subgroups is reported in Identification Methods for Microbiologists, Gibbs 
and Skinner (1966). The relative characteristics of Micrococcus Cohn 
subgroups 1 through 4 are set forth in U.S. Pat. No. 3,650,768, the 
disclosure of which is incorporated by reference. 
The proteolytic micrococcus to be used in accord with this invention will 
be acetoin positive and convert glucose to acid under aerobic conditions. 
It has been found that more preferred results are achieved with 
microorganisms from Micrococcus Cohn subgroup 2 and even more preferred 
results are obtained when the Micrococcus Cohn are microorganisms of 
subgroup 2 which are obtained from raw milk. 
It has been found that microorganisms from Micrococcus Cohn subgroups 5 
through 8, inclusive, are not satisfactory for the production of the 
desired high flavor level. Microorganisms in these subgroups 5 to 8, 
inclusive, are acetoin negative and some in these subgroups are weak or 
negative in converting glucose to acid under aerobic conditions. 
A preferred proteolytic micrococcus is a proteolytic micrococcus obtained 
from the University of Wisconsin designated T-3 and deposited in the 
American Type Culture Collection, No. 21829. The cultural and biochemical 
characteristics of T-3 micrococcus are also set forth in U.S. Pat. No. 
3,650,768. 
It has been found that when the Micrococcus Cohn subgroups 1 to 4, 
inclusive, microorganisms are added to the curd in addition to the lipase 
and protease, there is a clear contribution to the quality of the 
intensified cheese flavor that is not established without the addition of 
these microorganisms. It has also been found that this improvement is 
noticeable under the curing conditions described herein and is carried 
over into the products to which the cheese product of the invention is 
added. 
Proteolysis and lipolysis of the protein and fat in the cheese curd to 
provide the desired breakdown of protein and fat occurs during curing of 
the cheese curd. In this connection, the level of protein and fat 
breakdown is greatly enhanced in a shortened period of time when the 
lipase, protease, and proteolytic micrococcus combination of the invention 
are added to the curd particles after drainage of the whey and prior to 
pressing the curd particles into a cheese shape, and, as previously 
discussed, the C.sub.2 -C.sub.10 fatty acid content is increased to at 
least about ten times the C.sub.2 -C.sub.10 fatty acid content of 
conventional American-type cheese during curing. 
While not wishing to be bound by any theory, it is believed that the 
proteolytic micrococcus of the combination continues to grow slowly under 
the acidic conditions developed during curing of the cheese. In this 
connection, the proteolytic activity of the micrococcus is primarily due 
to products produced by and during the growth of the micrococcus and acts 
to hydrolyze the protein into various protein fragments in addition to the 
hydrolysis provided by the added protease. 
In accordance with the method of the present invention, the cheese 
containing the added source of lipase and added source of protease is 
cured, preferably at elevated temperatures as compared to usual curing 
temperatures for American-type cheese, until the desired C.sub.2 -C.sub.10 
fatty acid level is reached. It is usual to cure an American-type cheese 
product at a temperature of about 40.degree. F. The method of the present 
invention may utilize curing temperatures of up to about 100.degree. F. 
although it is usually desirable to provide a curing temperature in the 
range of from about 50.degree. F. to about 85.degree. F., preferably 
72.degree. F. The time required to develop an intensified flavor level is 
inversely proportional to the temperature at which curing is effected. At 
temperatures of 40.degree. F., the time required to develop a desired 
intensified flavor is usually from about six months to one year and this 
is considered to be an excessive curing time for the cheese product 
described herein. At curing temperatures approaching 90.degree. F. an 
intensified flavor may be developed in from about one month or less. 
However, too high curing temperatures may result in undesirable gas 
formation and development of off flavors and the like. Accordingly, it is 
preferred to cure at a temperature of 50.degree. F. to 85.degree. F., 
preferably 72.degree. F. for about six weeks whereupon a natural 
American-type cheese having an intensified flavor is obtained. If the 
temperature is then reduced to 45.degree. F., little additional flavor 
development occurs and the cheese product may be held for extended periods 
of time without development of off flavors and the like. 
A distinguishing feature of the cured, intensely flavored cheese product of 
the invention is that little knitting of the individual curd particles 
occurs. After curing, the cheese blocks may be easily crumbled to provide 
flavored curd particles of substantially the same shape as before curing 
which are particularly suitable for providing cheese flavor in various 
products, such as process cheese and baked goods. It is also possible to 
provide an intensely flavored cheese powder by preparing an aqueous slurry 
of comminuted cured cheese and thereafter spray-drying the slurry. 
The amounts of lipase that is added to the curd are selected to provide the 
desired C.sub.2 -C.sub.10 fatty acid development depending upon the 
temperature and length of the curing cycle. The lipolytic action, as well 
as the proteolytic action, on the cheese continue until inactivated, for 
example, by cooking or cooling to low temperature. 
When the throat tissue lipase described herein is used at a level of from 
about 20 to about 45 grams per 100 pounds of curd, the desired C.sub.2 
-C.sub.10 fatty acid content is achieved. Alternate lipase sources may be 
used at equivalent levels depending upon respective activities. 
The protease should be added at a level sufficient to provide a desired 
amount of protein breakdown to amino acids and peptides, but should not be 
added at such high levels as to generate undesired flavors. At levels of 
addition of a dry Rhozyme P-11 protease preparation below about 1 gram per 
100 pounds of curd, there is little flavor contribution to the level of 
amino acids produced. At levels of addition above about 10 grams of dry, 
powdered protease preparation per 100 pounds of curd, an off-flavor may be 
produced. Generally, between about 5 and about 7.5 grams per 100 pounds of 
curd is used. As with the lipase, other proteases may be added at 
equivalent levels depending upon activity. 
The proteolytic micrococcus, if used, is added at a level sufficient to 
provide a viable culture. 
When a natural cheese is produced containing the above-described 
combination of lipase, protease, and proteolytic micrococcus, the cheese 
has a desirable highly intensified American-type cheese flavor. However, 
the flavor may be unduly harsh for some purposes and a more rounded flavor 
may be desirable for some uses. It has been found that an improved rounded 
flavor can be provided when a lactobacillus or a closely related 
microorganism is also added to the curd on the drain table. Such a 
lactobacillus may be referred to as a flavoring microorganism. Addition of 
such a microorganism is optional, but may be used where a particular 
flavor is desired. Various homofermentative lactobacilli may be used, such 
as Lactobacillus lactis, Lactobacillus bulgaricus, and Lactobacillus 
caseii. Preferred homofermentative lactobacilli are particular strains of 
L. lactis and L. caseii. The lactobacillus microorganism will also develop 
some acidity in the curd during curing. However, as previously stated, the 
lactobacillus microorganism is primarily used when a particular flavor is 
desired. A preferred L. lactis microorganism has the following 
characteristics: 
______________________________________ 
Temperature 
for growth 15.degree. C. 
- 
22.degree. C. + 
37.degree. C. + 
45.degree. C. + 
55.degree. C. + 
Microscopic Evaluation + Rod 
Granules + 
Colony Appearance Rough 
NH.sub.3 from Arginine - 
Lipolytic (Spirit Blue) - 
Catalase - 
Litmus Milk: Acid Dye + 
Reduction + 
Coagulation + 
% Acid in Milk 1.74 
pH 3.3 
Acid from: Galactose .+-. 
Glucose + 
Lactose + 
Maltose .+-. 
Mannitol - 
Salicin + 
Sorbitol - 
Sucrose .+-. 
Trehalose + 
______________________________________ 
When used, the lactobacillus or closely related microorganism is added as a 
milk culture of the microorganism. The milk culture is obtained by adding 
the lactobacillus microorganism to a suitable substrate and permitting 
growth of the microorganism to proceed until an equivalent lactic acid 
acidity of from about 1.0 percent to about 2.0 percent is obtained. The 
milk culture of the lactobacillus organism is then added to the curd which 
has been separated from the whey at a level of from about 0.1 to about 1.0 
percent by weight of the culture per 100 pounds of curd. At levels above 
the stated range, an undesired flavor is sometimes detected. At levels 
below the stated range, there is little contribution to the flavor of the 
cheese produced from the curd after curing. 
The various enzymes and cultures, as described herein, are preferably added 
to the curd on the drain table and prior to pressing. However, it is 
contemplated to add all or a part of the enzymes to the curd after partial 
curing. In this instance, the curd blocks are comminuted to provide curd 
particles prior to adding the enzymes and cultures thereto. After the 
addition of the enzymes and cultures to the curd particles, the curd 
particles may be compacted into a cheese block prior to further curing, or 
loose curd particles may be further cured without compacting. 
It is recognized that the flavor contribution from the proteolytic 
micrococcus and the homofermentative lactobacillus flavoring microorganism 
may be due to an enzymatic reaction where an enzyme is produced as a 
product of the growth thereof during curing of the curd. In another 
embodiment of the present invention, such enzyme may be extracted from a 
proteolytic micrococcus or from a homofermentative lactobacillus culture 
and added directly to the curd as described herein. In such instances, the 
enzymes are added at a level equivalent to that which would be provided by 
the proteolytic micrococcus or the homofermentative lactobacillus if 
present. Similarly, the source of lipase and protease may be a culture 
medium instead of an isolate thereof which are described as the preferred 
embodiments herein. 
The method of the present invention is particularly suitable for the 
manufacture of highly flavored American-type cheese from heat-treated 
milk. As used in the cheese art, heat-treated milk is milk which has been 
heated to at least 135.degree. F. and cooled with no-hold. Such treatment 
generally destroys gas-forming microorganisms but is less than 
pasteurizing conditions, and such treatment may be referred to herein as 
subpasteurizing. The heat-treated medium may be pasteurized, which is 
generally understood to mean, in reference to milk, that the milk tests 
phosphatase negative, or may be sterilized, which is generally understood 
to mean that the microorganisms and enzymes present in the medium are 
substantially or completely destroyed. 
American or other cheese produced from pasteurized or otherwise 
heat-treated milk lacks the flavor characteristically associated with the 
American or other cheese produced from raw milk. The problem of flavor 
development becomes more difficult as the heat treatment is increased. The 
method of the present invention, as indicated, is particularly suitable 
for the manufacture of highly flavored cheese from pasteurized or 
otherwise heat-treated milk utilizing an inoculated milk as disclosed in 
U.S. Pat. No. 3,650,768. 
Various tests have been specified in the foregoing specification. These 
tests are generally standard and recognized tests so that the 
specification has not been elaborated with details as to test procedures. 
The following examples further illustrate various features of the present 
invention, but are intended to in no way limit the scope of the invention 
which is defined in the appended claims. 
EXAMPLE I 
1000 pounds of raw milk is subjected to pasteurization heat treatment of 
161.degree. F. for sixteen seconds. The milk is cooled to a temperature of 
88.degree. F. and is inoculated with an L. lactis culture at a level of 15 
pounds of the liquid culture per 1000 pounds of milk. 21/2 pounds of a 
Micrococcus Cohn culture, subgroup 2, identified as T-3 by the University 
of Wisconsin, and 1 pound of a liquid culture of L. caseii liquid culture 
are also added to the milk. The inoculated milk is fermented for a period 
of one hour at a temperature of 89.degree. F. until a titratable acidity 
of 0.165 is obtained in the milk. 
The milk is then set with 100 cc's of single strength calves rennet per 
1000 pounds of milk. A setting period of thirty minutes is allowed for 
coagulation of the milk after addition of the rennet. The coagulum that is 
formed is then cut into 1/4 inch curd cubes with curd knives. The 
titratable acidity of the whey at the time of cutting is 0.115. 
The curd is lightly stirred in the whey for a period of fifteen minutes 
after cutting and the curd is then cooked in the whey to a temperature of 
102.degree. F., allowing thirty minutes to attain the cooking temperature. 
The curd and whey are stirred vigorously for about ninety minutes after 
the cooking step until a titratable acidity in the whey of 0.165 is 
reached. 
Thereafter, the curd and whey mixture is pumped to a drain table while 
maintaining a temperature of 102.degree. F. The whey is drawn from the 
curd on the drain table until the whey level is slightly higher than that 
of the curd level. Further acidity is then developed in the curd while the 
curd and whey are maintained on the drain table. The remaining whey is 
drawn from the curd when the whey titratable acidity is 0.28 and the curd 
pH is 5.30. The whey is permitted to drain freely for about fifteen 
minutes. 94 pounds of curd are obtained. 
The curd is then divided into four 23-pounds lots designated as Lots I-A, 
I-B, I-C, and I-D. Each of the lots of curd is salted with sufficient salt 
to provide 2 percent salt on the basis of the curd weight and proteolytic 
and lypolytic enzymes are added to the curd in accordance with the 
following schedule: 
Lot I-A 7.5 grams Italase C; 5.25 grams Capalase KL 
Lot I-B 1.5 grams Rhozyme P-11 
Lot I-C 7.5 grams Italase C; 5.25 grams Capalase KL; 1.0 grams Rhozyme P-11 
Lot I-D 7.5 grams Italase C; 5.25 grams Capalase KL; 1.5 grams Rhozyme P-11 
Each of lots I-A, I-B, I-C, and I-D are divided into two portions for 
curing. All lots are cured at 72.degree. F. for four weeks. Thereafter 
one-half of each lot is transferred to a cooler and maintained at 
45.degree. F. and the other half is maintained at 65.degree. F. After 
approximately ninety days total elapsed time, the cheese products are 
analyzed for free fatty acid, the results of which are set forth in Table 
IV. 
TABLE IV 
______________________________________ 
Weight % Free Fatty Acid 
Age, 
Example Days C.sub.2 C.sub.4 
C.sub.6 
C.sub.8 
C.sub.10 
______________________________________ 
I-A-45.degree. F. 
91 0.063 0.295 0.128 0.047 0.102 
I-A-65.degree. F. 
91 0.137 0.421 0.156 0.055 0.116 
I-B-45.degree. F. 
92 0.100 0.012 0.010 0.009 0.011 
I-B-65.degree. F. 
92 0.160 0.023 0.016 0.013 0.018 
I-C-45.degree. F. 
93 0.120 0.319 0.132 0.047 0.107 
I-C-65.degree. F. 
93 0.127 0.405 0.164 0.057 0.105 
I-D-45.degree. F. 
87 0.054 0.296 0.119 0.038 0.081 
I-D-65.degree. F. 
87 0.132 0.397 0.143 0.046 0.085 
______________________________________ 
The free fatty acid distribution of Examples I-A through I-D are plotted in 
FIG. 2. Storage at 65.degree. F. results in increased fatty acid 
development, particularly in C.sub.4 fatty acids, as compared to storage 
at 45.degree. F. It is therefore possible to exert control over the fatty 
acid content of the cheese product by altering and/or controlling the 
curing temperature, and permits speeding up or slowing down of the curing 
cycle by appropriate temperature adjustments. The free fatty acid 
development is slowed even further if the temperature is reduced below 
45.degree. F. and is completely stopped if the cheese product is frozen. 
While freezing of cheese is undesirable if the cheese is to be consumed as 
is, it does not detract from the cheese product of the invention when it 
is used as a flavoring ingredient in process cheese or in baked goods. 
EXAMPLE II 
A cheese curd is produced in accordance with Example I and after whey 
removal a twenty-three pound sample of curd is salted and 7.5 grams 
Italase C, 5.25 grams Capalase KL, and 1.0 grams of Rhozyme P-11 are added 
to the curd. The curd is then cured at 72.degree. F. 
Quantities of the cheese product were removed and frozen after one day, 
fourteen days, and twenty-eight days to stop development of fatty acids. 
The respective samples were analyzed for free fatty acid content and for 
percent total nitrogen by molecular weight fractions. 
EXAMPLE III 
A further quantity of cheese is made in accordance with Example I except 
the milk is not inoculated with the T-3 micrococcus and liquid culture of 
L. caseii. After whey removal twenty three pounds of curd is salted and 
7.5 grams Italase C, 5.25 grams Capalase KL, and 1.0 grams Rhozyme P-11 
are added to the curd. The curd is then cured at 72.degree. F. 
Quantities of cheese were removed and frozen after one, fourteen, and 
twenty-eight days and analyzed for free fatty acid and for percent total 
nitrogen by molecular weight fractions in the same manner as Example II. 
The results of the analysis of Examples II and III are set forth in Tables 
V and VI. 
TABLE V 
______________________________________ 
Weight % Free Fatty Acid 
Age, 
Example Days C.sub.2 C.sub.4 
C.sub.6 
C.sub.8 
C.sub.10 
______________________________________ 
II-A 1 0.033 0.010 0.004 0.002 0.003 
II-B 14 0.024 0.025 0.086 0.028 0.056 
II-C 28 0.030 0.319 0.121 0.040 0.085 
III-A 1 0.022 0.005 0.002 0.001 0.001 
III-B 14 0.017 0.236 0.087 0.028 0.052 
III-C 28 0.024 0.311 0.115 0.038 0.073 
______________________________________ 
TABLE VI 
__________________________________________________________________________ 
Acid Molecular Weight Distribution 
Age, 
% Acid 
% Soluble N 50,000- 
10,000- 
1,000- 
Example 
Days 
Soluble N 
Total N 
Total N 
100,000 
100,000 
50,000 
10,000 
1,000 
__________________________________________________________________________ 
II-A 
1 0.2 3.8 5.3 -- -- -- -- -- 
II-B 
14 1.1 4.0 27.5 69.8 
20.0 
3.9 3.8 2.5 
II-C 
28 -- -- -- 63.3 
20.6 
7.9 3.9 4.3 
III-A 
1 0.2 3.6 5.6 -- -- -- -- -- 
III-B 
14 0.9 3.9 23.8 78.4 
13.8 
1.7 4.1 2.0 
III-C 
28 -- -- -- 65.5 
23.9 
3.5 3.2 3.9 
__________________________________________________________________________ 
The free fatty acid data of Table V is depicted graphically in FIGS. 3 and 
4 and illustrates the increase in free fatty acid as the curing process 
progresses. Except for the C.sub.2 fatty acids, there is a definite 
increase in fatty acid content with the C.sub.4 fatty acids increasing 
from a level of from about 0.01 to 0.02 percent at one day to in excess of 
0.3 percent at twenty-eight days. 
The molecular weight distribution data set forth in Table VI shows little 
difference between Examples II and III and compares favorably with 
conventional aged Cheddar cheese. 
EXAMPLE IV 
A further quantity of cheese is made in accordance with Example II with the 
further addition to the curd of 1 pound of T-3 micrococcus culture and 1 
pounds of L. caseii culture per 100 pounds of curd. The curd is then cured 
at 72.degree. F. 
Samples of the cheese product were taken and frozen at one day and 
twenty-eight days curing time and analyzed for free fatty acids in the 
same manner as Examples II and III and the following results were 
obtained. 
TABLE VII 
______________________________________ 
Age, 
Example Days C.sub.2 C.sub.4 
C.sub.6 
C.sub.8 
C.sub.10 
______________________________________ 
IV-A 1 0.033 0.027 0.010 0.003 0.002 
IV-B 28 0.027 0.350 0.138 0.045 0.106 
______________________________________ 
The data of Table VII is plotted in FIG. 5. Comparison of FIG. 5 with FIGS. 
3 and 4 show that the fatty acid development at the end of twenty-eight 
days is greater in Example IV than in Examples II and III and this is 
believed to be due to the addition of the proteolytic micrococcus and 
flavoring microorganism to the curd and also the addition of lipase to the 
milk as well as to the curd. 
EXAMPLE V 
Process cheese is made incorporating varying levels of the natural cheese 
of intensified flavor prepared in accordance with Example IV. A basic 
preblend comprising 40 percent body cheese approximately one month old, 30 
percent short held cheese approximately three months old, and 30 percent 
aged Cheddar cheese is prepared. Five process cheese samples are prepared 
in which 5 percent, 10 percent, 20 percent, 30 percent, and 50 percent of 
the preblend is replaced by the intensely flavored cheese of Example IV. A 
control sample containing no added intensely flavored cheese is also 
prepared. 
The process cheese samples are prepared in accordance with conventional 
processing techniques by heating the comminuted cheese together with usual 
emulsifier salts to a temperature of 165.degree. F. for a period of time 
sufficient to cause the cheese particles to melt and form a homogeneous 
mass. The process cheese is then packaged and refrigerated. 
The process cheese samples containing the intensely flavored cheese of 
Example IV were compared against the control sample for American cheese 
flavor. All samples were judged to have a more pronounced American cheese 
flavor than the control sample. The 50 percent sample flavor was 
considered too strong for average consumption and the samples containing 5 
to 30 percent intensely flavored cheese were considered acceptable. 
EXAMPLE VI 
1000 pounds of raw milk is subjected to subpasteurization heat treatment of 
135.degree. F. for five seconds. The milk is cooled to a temperature of 
88.degree. F. and is inoculated with an L. lactis culture at a level of 
13.0 pounds of the liquid culture per 1000 pounds of milk. The inoculated 
milk is incubated for a period of one hour at a temperature of 88.degree. 
F. until a titratable acidity of 0.17 percent is obtained in the milk. 
The milk is then set with 100 cc's of single strength calf rennet per 1000 
pounds of milk. A setting period of thirty minutes is allowed for 
coagulation of the milk after addition of the rennet. The coagulum that is 
formed is then cut into 1/4 inch curd cubes with curd knives and the 
titratable acidity of the whey at the time of cutting is 0.11. 
The curd is lightly stirred in the whey for a period of fifteen minutes 
after cutting and the curd is then cooked in the whey to a temperature of 
103.degree. F., allowing thirty minutes to attain the cooking temperature. 
The curd and whey are stirred vigorously for about ninety minutes after 
the cooking step until a titratable acidity in the whey of 0.17 and a curd 
pH of 5.80 are reached. 
Thereafter, the curd and whey mixture is pumped to a drain table while 
maintaining the cooking temperature of 103.degree. F. The whey is drawn 
from the curd on the drain table until the whey level is slightly higher 
than that of the curd level. Further acidity is then developed in the curd 
while the curd and whey are maintained on the drain table. The remaining 
whey is drawn from the curd when the whey titratable acidity is 0.28 and 
when the cured pH is 5.30. The whey is permitted to drain freely for about 
fifteen minutes and the curd is then salted by adding 2.0 pounds of sodium 
chloride salt per 1000 pounds of milk. 19.9 grams of Italase C enzyme 
obtained from the throat tissue of calves and 14.0 grams of Catalase K 
enzyme obtained from the throat tissue of kids or lambs is then added per 
100 pounds of curd. A protease enzyme, designated Rhozyme P-53, is added 
at a level of 5.75 grams of enzyme per 100 pounds of curd. 
The enzymes and salt are thoroughly mixed in the curd and the curd is then 
packed into hoops at a level of 45.0-47.0 pounds of curd per hoop. The 
curd is pressed in the hoop at a pressure of 17 psi for a period of about 
twelve hours at room temperature so as to drain additional whey from the 
curd and to press the curd into a cheese block. The cheese block is then 
removed from the hoop and is subjected to 25 inches of vacuum for one 
hour. The cheese block is then packaged in a foil wrapper and is cured for 
six weeks at a temperature of 72.degree. F. At the end of the six weeks 
period, the curd has developed a highly intensified flavor, which flavor 
level is substantially higher than usually associated with American-type 
cheese. The flavor level is judged to be too intense for direct eating, 
but is considered very suitable for use as an ingredient in the 
manufacture of process cheese. 
EXAMPLE VII 
1000 pounds of raw milk is subjected to pasteurization heat treatment of 
161.degree. F. for thirty seconds. The milk is adjusted to a temperature 
of 88.degree. F. and is inoculated with an L. lactis culture at a level of 
13.0 pounds of the liquid culture for each 1000 pounds of milk. A 
Micrococcus Cohn subgroup 2 liquid proteolytic culture, ATCC No. 21829, is 
added to the milk at a level of 2.5 pounds of liquid culture per 1000 
pounds of milk. An L. caseii liquid culture is also added to the milk at a 
level of 2.0 pounds of the culture per 1000 pounds of milk. Italase C 
lipase is added to the milk at a level of 0.25 grams per 1000 pounds of 
milk. Catalase KL lipase is added to the milk at a level of 0.17 grams per 
1000 pounds of milk. The inoculated milk medium is then set and curd is 
manufactured by the stirred curd process described herein. Lipase and 
protease are then added to the curd as set forth in Example VI. The curd 
particles are formed into a cheese and the cheese is then cured for six 
weeks at a temperature of 72.degree. F. At the end of the six weeks period 
the cheese has developed a highly intensified flavor, which flavor level 
is substantially higher than usually associated with American-type cheese. 
The flavor level is judged to be too intense for direct eating, but is 
considered very suitable for use as an ingredient in the manufacture of 
process cheese. Process cheese containing 10 percent of the cheese product 
of this Example has a desirable American cheese flavor and is considered 
to be of excellent quality. 
EXAMPLE VIII 
1000 pounds of raw milk is made into curd particles in accordance with the 
procedure of Example VI. A mixture of lipase and protease is added to the 
curd particles as described in Example VI. A Micrococcus Cohn subgroup 2 
proteolytic micrococcus, ATCC No. 21829, is added to the curd particles 
prior to curing at a level of 1.0 pounds of culture per 100 pounds of 
curd. An L. lactis liquid culture is also added to the curd particles at a 
level of 1.0 pounds per 100 pounds of curd. The curd particles are then 
formed into a cheese and the cheese is cured as described in Example VI. 
After curing, the cheese has a desirable high level of flavor that is 
judged to be somewhat less harsh than the flavor of the cheese prepared in 
accordance with Example VI. 
EXAMPLE IX 
A 40-pound block of cheese prepared in accordance with the method of 
Example V is crumbled by hand to provide curd particles. The cheese block 
is easily crumbled and the curd particles appear to retain their identity 
throughout the curing period. 
The curd particles are added to a bread dough formulation at the time of 
mixing the dough. After the bread dough has been baked, a cheese-flavored 
bread is obtained with a high and desirable level of Cheddar cheese 
flavor. The curd particles are slightly melted but discrete curd particles 
are discernible in the bread. The flavor is substantially more intense 
than is obtained when Cheddar cheese produced by a conventional 
manufacturing process is added to bread dough. 
EXAMPLE X 
Three samples of cheese having intensified American cheese flavor are 
prepared in accordance with Example I utilizing papain as the source of 
proteolytic enzyme. In each of Samples X-A, X-B, and X-C the lipase source 
added to the curd prior to curing is 7.5 grams Italase C, 5.25 grams 
Capalase KL. Sample X-A has 0.01 gram papain added; Sample X-B has 0.10 
gram papain added; Sample X-C has 1.0 gram papain added. The curd is then 
cured at 72.degree. F. 
After approximately twenty-five days, the samples are analyzed for free 
fatty acid content, the results of which are set forth in Table VIII. 
TABLE VIII 
______________________________________ 
Sample C.sub.2 C.sub.4 C.sub.6 
C.sub.8 
C.sub.10 
______________________________________ 
X-A 0.038 0.257 0.092 0.025 0.051 
X-B 0.027 0.249 0.090 0.025 0.047 
X-C 0.048 0.240 0.085 0.022 0.043 
______________________________________ 
After curing at 72.degree. F. for six weeks, each of the cheese samples has 
a highly intensified American-type cheese flavor and each is useful as a 
flavoring ingredient for process cheese.