TEXAS AGRICULTURAL EXPERIMENT STATION

A. B. CONNER, DIRECTOR,
College Station, Texas

BULLETIN NO. 646 FEBRUARY 1944

FACTORS AFFECTING THE QUALITY
OF SOUTHERN SHORT CURE
CHEDDAR CHEESE

F. E. HANSON, W. S. ARBUCKLE
and C. N. SHEPARDSON

Division 0f Dairy Husbandry
Department of Dairy Husbandry

 

AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS
F. C. BOLTON, Acting President

D-15-244-—4M '

LIBRARY

L
a M’ COLLEGE OF TEXAQ

[Blank Page in Original Bulletin]

This bulletin contains the results of an investigation made to
determine the factors which affect the quality of short cure ched-
dar cheese. Studies have been made concerning the effect of ri-
pening temperature, amount of re-nnet extract used and manufac-
turing methods upon the quality of the ripened cheese by compar-
ing the ripening temperatures of 45°, 60°, 70° and 80°F., by using
2, 4 and 8 ounces of rennet per 1000 pounds of milk and by compar-
ing the quality of cheese manufactured by the cheddar, stirred curd
and washed curd methods.

The temperature of ripening and the amount of rennet extract
used were factors of most importance in the production of a high
quality short cure cheese. The stirred curd and washed curd meth-

' ods of manufacture were of little value in the production of a short

cure cheese.

A high quality cheese was produced within a four weeks period.
The best cheese produced within a four weeks period was ripened
for two weeks at 45°F. and two weks at 60°Fahrenheit. The best
cheese produced within an eight weeks period was ripened for two
weeks at 45°F. and six weeks at 60°Fahrenheit. This cheese was
slightly superior to the cheese ripened only four weeks. The use
of 4 ounces of rennet per 1000 pounds of milk proved the most
satisfactory of the various amounts of rennet used for the produc-
tion of a short cure cheese. The cheddar method proved superior
to either the stirred curd or washed curd methods of manufacture.

CONTENTS

  

"~ Page
Introduction ............................................................................................................... .. 5 '_
Review of Literature .............................................................................................. .. 5
Procedure ................................................................................................................... .. 7 a

Manufacturing methods .................................................................................. .. 7 p

Methods of grading and analysis ................................................................ .. 8 1
Preliminary investigation .................................................................... .; ........ ._11
Effect of temperature upon ripening .......................................................... ..15 i
Effect of amount of rennet extract upon ripening of cheese at .'
various temperatures ................................................................................ _.15 g
Effect of stirred curd and cheddar methods of manufacture upon 1
the rate of ripening .................................................................................. ..16 
Effect of high acidity and washing treatments of curd upon rate i
of ripening .................................................................................................. ..16 i;
Results ..................................... .., ................................................................................ ..16 ’,
Effect of various ripening temperatures upon the rate of ripening .... ..16 j
Experimental groups ...................................................................................... ..16 
Effect of the amount of rennet extract upon quality and rate of 
ripening at various temperatures .......................................................... ..22 a
Effect of stirred curd and cheddar methods upon the rate of
ripening .................................................................................... ..- .................. ..24
The effect of high acidity and of Washing the curd upon the g_
quality of cheese ........................................................................................ ..26
Discussion ................................................................................................................... ..26 i
Conclusions ................................................................................................................ ..29

Literature Cited ....................................................................................................... ..30 i

 

FACTORS AFFECTING THE QUALITY
OF SOUTHERN SHORT CURE
CHEDDAR CHEESE

F. E. Hanson,‘ W. S. Arbucklef and C. N. Shepardson“

Cheddar cheese has been made for many years, but no work was at-
tempted to scientifically explain the ripening of cheese until fifty years ago.
Since that time many investigators have studied ripening problems and
much has been accomplished. Any study of cheese ripening is complicated
by the many variable factors involved. Some of the first experimental work
reported on the problem showed that a better flavor was developed when
cheese was ripened at a temperature of about 40°F., and also that cheese
could be held in storage a longer time with more desirable results at this
temperature. In those days, bad flavors caused by coli-aerogenes and other
undesirable bacteria were common, and no doubt the activities of these bac-
teria were reduced by the lower temperature. Hence, it was the common
practice to ripen cheese for a long period of time at a low temperature in
order to secure a high quality product. Many changes have taken place in
the cheese industry since those early investigations. The use of bacterial
starters, cleaner milk, pasteurization, improved cheese making equipment,
and more sanitary methods, all have enabled the production of a better
quality of cheese for the curing room.

Today the cheese factory operators and cheese dealers are not as much
interested in being able to store cheese for a long period of time as they are
in hastening the ripening, thereby decreasing the span of time between the
production of the milk and the ultimate consumption of the cheese. This is
especially true here in the South as the high cost of cold storage causes the
dealer to shorten the ripening period; thus much of the cheddar or American
cheese sold over the retail counter is not sufficiently ripened as indicated by
lack of flavor and the presence of a firm rubbery body. Any modifications
of the manufacturing and ripening methods which would produce a higher
quality short cure cheese would therefore be highly desirable.

REVIEW OF LITERATURE

A review of the literature reveals that there are many factors that in-
fluence the ripening of cheese. Some of these factors which can be con-
trolled by the cheesemaker include the amount of rennet or other enzymes
present, amount of salt, acidity of cheese, moisture content of cheese, curd
treatment, and ripening temperature.

Enzymes. The importance of rennet in the ripening of cheese is not
well established. Babcock and co-workers (4) quoted that quantities of ren-
net increased protein decomposition, stating that this was probably due to
the presence of pepsin in the extract. Doane (6) and Sammis (16) working
independently stated that using a larger amount of rennet extract caused
cheese to ripen faster. Sherwood (17) maintained that different lots of

 

lFormer Associate in Dairy Manufacturers, resigned August 31, .1942.
iAssociate in Dairy Manufacturers.
“Head, Department of Dairy Husbandry, Agricultural and Mechanical College of Texas.

6 BULLETIN NO. 646, TEXAS AGRICULTURAL EXPERIMENT STATION

pepsin or rennin may possess different proteolytic powers. Harding (10) A

stated that the action of rennet enzymes extend only to the production of

peptones. Freeman (8) found that additional amounts of pure rennin in- a

creased the rate of proteolysis in cheddar cheese ripening, increased slightly
the rate at which the flavor developed, and produced an aged product with
a slightly higher flavor score. He also found that added pepsin increased
the rate of proteolysis during cheddar cheese ripening, particularly at the
beginning of the ripening period and at the lower ripening temperature;
however, it did not accelerate the development of flavor, but produced an
aged product with appreciably higher flavor score.

Salt. Marquardt (11) studied the relationship of salt content to the
quality of cheddar cheese and stated that the addition of 1% to 3 per cent
salt did not affect the body of the cheese, but cheese to which 3 per cent salt
was added scored one point lower on flavor than the cheese to which 1% and

21/1 per cent of salt was added. He also states that these results are h l

close agreement With those previously reported by Riddet (15).

Acidity. Haglund, et al. (9) and Townsend (19) found that increasing 
the acidity of the milk at coagulation time increased the formation of water ._
soluble nitrogenous compounds during ripening. Price (14) found that 

there was a correlation between high acidity and bitter flavor in cheese.

Phillips (13) has shown that a high acid cheese ripens slower than one with f‘:
low acidity. Freeman (8) states that low initial acidity was conducive to ‘l
more rapid proteolysis but had no effect on the rate of flavor development, 
and also that flavor was slightly inferior in low acid cheese. Doane, Ader- 
hold and Wilson (7) suggested in an article discussing acidity development 
in the manufacture of cheddar cheese, that cheese made with low acidity de- 

velopment and good milk can be ripened at higher than usual temperatures
with a favorable effect upon the quality of the finished product.

Moisture Content. Van Slyke and Hart (20) found that a higher
water content of cheese was conducive to a more complete proteolysis.
Sammis (16) claimed that it was desirable to incorporate more moisture in
producing a quick curing cheese.

Curd Treatment. Marquardt (11) in comparing cheddar and granular
type cheeses states that cheddaring the curd improved the score 2.4 points
over the lowest scoring granular type cheese and 0.3 point over the best
granular type cheese. He observed that variation in cooking temperature
between 96° and 108°F. did not materially affect the quality of the cheese,
but there was a definite moisture decrease with an increase in cooking tem-

perature. Also curd salting produced better cheese than brine salting or a

rubbing.

Ripening Temperature. Smith (18) and Van Slyke, Smith and Hart *
(22) in early investigations found that lower ripening temperatures resulted f

in. a cheese of high score value. Van Slyke and Hart (20) state that be-
tween 32° and 72°F. each one degree increase in temperature resulted in 0.5
per cent increase in soluble nitrogen, the greater portion of the increase
being in the form of amino acids and ammonia. Atkinson (3) observed that
a ripening temperature between 40° and 60°F. was best for producing a
cheese of g00d flavor. Wojtkiewicz and Inikkoff (23) concluded that the
use of higher ripening temperatures for producing quick ripened cheese is

FACTORS AFFECTING THE QUALITY OF SOUTHERN CHEDDAR CHEESE '7

of limited value. Freeman (8) compared ripening temperatures of 45° and
63°F. and found that proteolysis in cheddar cheese ripening can be in-
creased 40 to 100 per cent by raising the ripening temperature from 45° to
63°Fahrenheit. The maximum score was reached more quickly when cheese
was ripened at 63°F., and the cheese ripened at this temperature attained a
higher maximum score. However, he stated that the higher ripening tem-
perature favored the occurrence of bitter flavor. Van Slyke and Price (21)
cited the technics used by Allen (2) and Bartel, Sandberg and Haglund (5)
as being reliable means of determining ripening, and Allen (2) stated that
the method, used by many workers in the past, of determining the amount of
soluble nitrogen present at different intervals of ripening, merely gave an
estimate of the total nitrogen but no information of the different types of
nitrogen. Bartel, Sandberg, and Haglund (5) described a method of secur-
ing a uniform sample for analysis in studying the ripening of cheese, and
state that rennet and bacterial action are the two most important factors in-
fluencing the rate of ripening.

The effect of many factors upon the ripening of cheese seems to be
fairly well established. Nevertheless, there is no complete theory of ripen-
ing that is universally accepted today, and there is need for detailed infor-
mation concerning the effect of various ripening treatments upon the quality
of the finished product and the proteolysis that takes place during the
ripening process in the production of a short cure cheese. -

PROCEDURE

This investigation was conducted by the Texas Agricultural Experiment
Station in cooperation with the Department of Dairy Husbandry. A pre-
liminary investigation was conducted to determine the important factors in-
fluencing the quality of short cure cheese. ‘Those factors, which proved to
be important in influencing the quality of cheese, were then studied in more
detail by making a number of lots of cheese using different methods of
manufacture. The cheese was ripened by various treatments. Flavor, body
and texture, ripening observations and chemical analyses of the different
lots of cheese were recorded at intervals during the ripening period.

Manufacturing Methods

Unless otherwise stated the cheese used in this investigation was made
from pasteurized milk that tested approximately 3.7 per cent butterfat. Two
per cent starter was used, and the milk was set at 86°F. using three and
one-half ounces of rennet per 1000 pounds of milk. The curd was cut with
one-half inch curd knives and was cooked at 98° to 102°Fahrenheit. The
acidity of the whey at dipping time was .15 per cent, and the curd was
milled when the acidity had developed to .5 per cent. Salt was added at the
rate of two and one-half pounds per 1000 pounds of milk. The cheese was
pressed into hoops and was later sealed into ten ounce valve vented cans for
ripening. This type can was used because it provided a means of controlling
surface mold growth and also a convenient portion of cheese for ripening
and scoring. Figure 1. shows the type of hoop and the valve vented can
used in this investigation.

8 BULLETIN NO. 646, TEXAS AGRICULTURAL EXPERIMENT STATION

Figure 1. The Cheese Hoop and Valve Vented Can Used.

Methods 0f Grading and Analysis

The score value of the cheese was determined by the U.S.D.A. cheese
score card which gives flavor 30, body and texture 40, make up 20, color 10,
total 100 for maximum scores. In this investigation only the flavor and the

I body and texture scores were determined. The make up of all lots of the

cheese was the same since ten ounce portions of the cheese were sealed in
the valve vented cans for ripening. A study was not made of the color
score values as the color was similar for the cheese within each series. In
cases where a total score is given, the make up and color were considered
perfect.

The following general classification was used to rank and describe the
flavor and the body and texture in determining a high quality cheese: for
flavor, perfect 30, excellent 25 or above, good 24 to 25, acceptable 23 to 24,
and inferior less than 23; for body and texture, perfect 40, excellent 39 or
above, good 37 to 39, acceptable 36 to 37 and inferior less than 36. The de-
gree of ripeness was not determined solely from flavor and body scores
given, but also included the observations of the judges as to their opinion of
the ripening qualities of the cheese. The score values presented represent
the average scores given by three experienced judges. The number of
samples of cheese examined by the judges varied with the different series,
but ranged from three to thirteen samples. As a measure of the rate of
ripening, chemical analyses were made to determine the amount of various
protein fractions present at intervals during the ripening process.

The moisture content was determined by drying a two to three gram
sample of cheese for 24 hours at 100°C. plus two-hours at a vacuum of 20
to 25 inches.

 

FACTORS AFFECTING THE QUALITY OF SOUTHERN CHEDDAR CHEESE 9

The pH of the cheese was determined by the use of a Coleman poten-
tiometer.

The fat content of the milk and cheese was determined by the Babcock
method.

The firmness of the cheese was found by the use of a penetrometer
developed by this laboratory. The hardness of the cheese was measured by
recording the weight of mercury required to press a plunger into the cheese
displacing approximately .2 cc. volume. The plunger was 4 mm. in diameter
and xvas depressed 14.7 millimeters. The plunger operated in a pipe sleeve
that was 11 cm. long. A small platform was mounted on the upper end of
the plunger on which a beaker was placed to collect the mercury. The
mercury was allowed to flow from a separatory funnel through a glass tip.
The opening in the tip was such that the rate of flow was 600 grams per
minute. These parts were mounted on a ring stand. Ten ounce samples
were tempered at 60°F. for 24 hours or more before determining the hard-
ness. An average of five determinations on each sample was taken to rep-
resent the hardness value. Figure 2. shows the penetrometer used.

The analyses made to establish the rate of ripening included the total
nitrogen content of the cheese, the water soluble nitrogen which represents
the per cent of the total nitrogen present in water suspension under the
stated conditions, the water soluble nitrogen not precipitated by trichlora-
cetic acid which indicates the non-protein nitrogen present, the water soluble
nitrogen not precipitated by tannic acid-salt solution and the water soluble
nitrogen not precipitated by phosphotungstic acid which are somewhat simi-
lar in their indication of the per cent amino nitrogen, but differ in the kind
of amino acids they separate. Although the tannic acid-salt and the phos-
photungstic acid methods are similar in their indications, both methods were
used in this investigation as there is some question as to which is most valu-
able in determining cheese ripening.

In the tables the total nitrogen is expressed as percentage of the weight
of the cheese and the fractions as the percentages of the total nitrogen.

Total nitrogen was determined in a one gram sample of cheese by the
Kjeldahl-Gunning-Arnold method (1).

The nitrogen fractions were determined by a micro-Kjeldahl method.
The different nitrogen fractions were prepared as follows: A water soluble
nitrogen solution of the cheese was obtained by mixing 10 gm. of cheese
and 96 ml. of water and agitating with a stirring device at about 5000 r.p.m.
for five minutes at room temperature. The solution was then digested in a
water bath at 50° to 55°C. for one hour after which the solution present be-
low the fat layer was removed with a pipette and filtered through a dia-
tomaceous filter to obtain a clear filtrate. The water soluble nitrogen was
found by using 1 to 3 ml. of this filtrate for the nitrogen determination.

The water soluble nitrogen not precipitated by trichloracetic acid was
determined by placing 10 ml. of the water soluble nitrogen filtrate in a test
tube and adding 10 ml. of a solution containing 2 parts of a 20 per cent tri-
chloracetic acid solution and 8 parts of water. The test tube was stoppered,
and the contents were mixed. On the following day, the solution was fil-
tered, and 2 or 3 ml. of the filtrate were used for the nitrogen determina-
tion. "

10 BULLETIN NO. 646, TEXA AGRICULTURAL EXPERIMENT STATION

Figure 2. Penetrometer Used to Determine Hardness of the Cheese.

FACTORS AFFECTING THE QUALITY OF SOUTHERN CHEDDAR CHEESE 11

The water soluble nitrogen not precipitated by tannic acid-salt solution
was secured by mixing 5 ml. of the water soluble nitrogen filtrate and 12%
ml. of 30 per cent sodium chloride solution. The mixture was cooled to
12°C., and 7% ml. of 24 per cent tannic acid solution were added. On the
following day the solution was filtered, and 2 ml. of the filtrate were used
for nitrogen analysis.

The water soluble nitrogen not precipitated by phosphotungstic acid
was determined by placing 5 ml. of the water soluble nitrogen_ filtrate in a
test tube and adding 5 ml. of a mixture consisting of 2 parts of a 10 per
cent phosphotungstic acid solution and 3 parts of 25 per cent sulfuric acid.
The test tube was stoppered, and the contents mixed. On the following day,
the solution was filtered, and 3 ml. of the filtrate were used for the nitrogen
determination.

The nitrogen content of the various fractions was found by measuring
the filtrate of the different fractions into 30 ml. Kjeldahl flasks. Then 11/2
to 2% ml. of concentrated sulfuric acid and 11/2 to 2 gm. of Gunning-Arnold
catalyst (1) (15 parts K2SO4 and .7 parts HgO) were added, and the con-
tents were digested for 30 minutes on a six place heater. After the diges-
tion period, the flasks were air cooled, and 3 ml. of 8 per cent sodium thio-
sulfate solution were added. The flasks were placed in an ice water bath,
and 6 to 7 ml. of 30 per cent sodium hydroxide solution were added. The
ammonia was distilled by steam distillation and collected in 20 ml. of boric
acid solution consisting of one part of a stock boric acid solution and six
parts of water. The stock solution of boric acid was made according to the
procedure of Menefee and Overman (12). Five drops of an indicator solu-
tion were added; this indicator consisted of 100 mg. of methyl red and 30
mg. of methylene blue dissolved in 60 ml. of 95 per cent ethyl alcohol and
made up to 100 ml. with distilled water. The ammonia was titrated with
.01 normal sulfuric acid.

Figure 3. shows the apparatus designed and used for the steam dis-
tillation of the ammonia in the digested sample. The apparatus consisted
of three units; namely, (1) the steam generator, (2) the distilling head and
(8) the condenser. The units were assembled by the use of rubber. A
plain two-hole stopper was used in the neck of the steam generator, a
modified stopper connected the digestion flask to the distilling head, and a
rubber tube connected the distilling head to the condenser. A piece of
rubber tubing was used on the steam lead to allow the removal and re-
placing of the digestion flask without breakage. The apparatus eliminated
the difficulties of sucking back and the necessity of rinsing the digested
sample from the digestion flask into the distilling apparatus. It also has
the advantage of being more rapid than similar apparatus suggested in the
literature, and at the same time does not sacrifice accuracy.

Preliminary Investigation

Preliminary work was done in 1936 and 1937 to obtain information con-
cerning the effect of variations in the manufacturing methods upon the
quality of short cure cheese.

Rennet. In a series consisting of seven paired lots of cheese made from
pasteurized milk, the effect of nine ounces of rennet extract per 1000

12 BULLETIN NO. 646, TEXAS AGRICULTURAL EXPERIMENT STATION

Figure 3. The Micio-Kjeldahl Distilling Apparatus.

FACTORS AFFECTING THE QUALITY OF SOUTHERN CHEDDAR CHEESE 13

pounds of milk was compared to the control in which three ounces of rennet
were used per 1000 pounds of milk. Comparisons were made after the
cheese was ripened for 11 weeks at 50°Flahrenheit. The results, as given in
Table 1, show that after eleven weeks of ripening at 50°F. the control lots
of cheese were of higher quality than the lots of "cheese containing nine
ounces of rennet. Two defects, a bitter flavor and a sticky body, appeared
frequently in the experimental lots containing the additional amount of ren-
net. The occurrence of the sticky body indicated that the rennet extract
was effective in breaking down the body. The bitter flavor was a more
serious defect and indicated the use of excess rennet.

Table 1. The effect of rennet extract upon the quality, pH and moisture content of
cheese ripened at 50°F. for 11 weeks

_ _ Rennet extract per 1000 lbs. of milk
Characteristic
3 oz. 9 oz.
Flavor score 24.12 23.62
(acceptable) (acceptable)
Body and texture score 36_88 36,56
(acceptable) (acceptable)
pH — 3rd day 5.05 5.11
pH — 5th week 5,04 5,11
Moisture per cent — 1st day 36.16 36.76
liumber of samples i 7 7

v Salt. A series of three trials was used to study the effect of the
amount of salt on the ripening qualities of cheese. One portion of curd was
salted at the rate of two pounds per 1000 pounds of milk, and another was
salted at the rate of 3% pounds per 1000 pounds of milk- The cheese was
examined for quality after a ripening period of ten weeks at 50°Fahrenheit.
The results of the study to determine the effect of the amount of salt upon
the quality of cheese showed that at the end of a 10 weeks ripening period
the lots containing 2 pounds of salt per 1000 pounds of milk were flat in
flavor; whereas, the lots having 31/; pounds of salt per 1000 pounds of milk
were salty in flavor and hard in body. This indicates that the range in the
amount of salt that can be added to cheese without injuring the quality is
quite narrow. v

Method of Manufacture. To compare the ripening qualities of Colby or
stirred curd type cheese with the cheddar type, six lots of stirred curd and
six lots of cheddar cheese were made and ripened at 50°F. for 10 weeks.
Table 2 shows a comparison of the ripening qualities of stirred curd type and
cheddar type cheese. The stirred curd cheese was better in flavor but
slightly inferior in body. It was slightly acid in flavor; whereas, the ched-
dar type cheese had a flat flavor. The body of the stirred curd cheese was
short and that of the cheddar cheese was softer and smoother. The stirred
curd cheese was slightly inferior to the cheddar type cheese; however, a
further study of this phase of the work seemed advisable as the stirred curd
type cheese was superior in flavor development.

i

14 BULLETIN NO. 646, TEXAS AGRICULTURAL EXPERIMENT STATION

Table 2. The effect of two methods of manufacture upon the quality, pH and moisture
content of cheese ripened at 50°F. for 10 weeks

l
i

3
i


Characteristics Cheddar Method Stirred Curd Method 
Flavor score 23.87 24,37
(acceptable) (good)
Body and texture score 37,66 37,08
(good) (good)
pH — 3rd day 5.09 5.05
pH — 7th Week 5.22 5.10
Moisture per cent—— 1st day 38.41 38.46
Number of samples G 6

Ripening Temperature. The effect of ripening temperature upon the *

quality of Colby cheese was studied in a series of three trials. Half of the

cheese in each trial was ripened at 70°F., and the other half was ripened at .

50°F. for a period of 7 weeks. The effect of ripening temperature upon the

quality of Colby cheese is shown in Table 3. The average flavor score of the g
cheese held at 70°F. was described as being medium full and was better than l
that of the cheese held at 50°Fahrenheit. Although the cheese held at the f
higher temperature was crumbly and inferior in body, it rated the same total 1
score as did the control. There was a considerable loss in moisture during l
the ripening period in the cheese ripened at 70°F., but this loss did not occur 4

in cheese ripened at 50°Fahrenheit.

Table 3. The influence of ripening temperature upon the quality, pH and moisture of
Colby cheese ripened for 7 weeks

Characteristics Rlpemng Temperature
50°F. 70°F.
Flavor score 23.83 24.17
(acceptable) (good)
Body and texture score 35.34 35.00
(inferior) (inferior)
pH — 3rd day 5.0T 5.07
pH ——— 7th week 5.09 —
Moisture per cent— 1st day 37.84 37.84
Moisture per cent — 7th week 38.09 34.84
Number of samples 3 3

Curd Treatment. In another series the effect of ripening washed curd
cheese at different temperatures was studied by washing one-half of the
curd in each of ten lots; Whereas, the other half was not washed and was
used as a control. One-half of the washed curd cheese and one-half of the
control were ripened at 70°F. While the other portions were ripened at
50°Fahrenheit. The results showing a comparison of the effect of washed
and unwashed curd cheese ripened at different temperatures upon the qual-

A ity of cheese are presented in Table 4. The washed curd cheese was superior

 

FACTORS AFFECTING THE QUALITY OF SOUTHERN CHEDDAR CHEESE 15

to the control in the flavor and body scores. The washed curd lots ripened
at 70°F. were slightly better in flavor than the washed curd lots ripened at
50°F.; however, the reverse was true in regard to body. The control lots of
cheese that were ripened at 70°F. were lower in quality than the control
lots ripened at 50°Fahrenheit. The washed curd cheese which was ripened
at the lower temperature was criticized for being flat in flavor; whereas, the
unwashed curd cheese that was ripened at the higher temperature had a
slight acid flavor.

Table 4. A comparison of the ripening qualities of unwashed and washed curd cheese
at different temperatures

Control Washed Curd
Characteristics Ripening temperature Ripening temperature

50°F. 70°F. 50°F. 70°F.
Flavor score 24.07 23.70 24.17 24.50

(good) (acceptable) (good) (good)
Body and texture score 36.34 35.68 37.00 36.38

(acceptable) (inferior) (good) (acceptable)

pH ~ 3rd day 5.08 5.08 5.10 5.10
pH — 7th week 5.09 5.13 5.26 5.31
Moisture per cent——1st day 38.05 38.05 39.79 39.79
Moisture per cent—7th week 37.49 36.82 39.43 38.16
Number of samples 10 10 10 10

Effect of Temperature Upon Ripening

After the preliminary investigation was completed, a more compre-
hensive study was conducted to determine the effect of temperature upon
the ripening of cheese. Thirteen different lots of cheese were ripened at
temperatures of 45°, 60°, 70° and 80°F. for various time intervals. The cur-
ing program was carried out by placing one lot of cheese at each of the tem-
peratures. Three other lots of cheese were held at 45°F. for 2 weeks, and
then one lot was held at each of the temperatures of 60°, 70° and 80°F. for
six weeks.

Three more lots were held at 45°F. for 4 weeks, and then one lot was
held at each of the other temperatures studied for 4 weeks. At the end
of eight weeks all lots were returned to the 45°F. temperature for another
period of eight weeks to determine if ripening could be checked success-
fully.

Another lot of cheese was ripened at each of the above temperatures for
16 weeks, and still another lot was held at each of the ripening tempera-
tures of 60°, 70° and 80°F. for 8 weeks, and then held at 45°F for another
8 weeks. The above described procedure gave information upon 34 different
ripening combinations.

Effect of the Amount of Rennet Extract Upon Ripening of Cheese
at Various Temperatures
In order to determine the effect of the amount of rennet extract upon
the quality of cheese ripened at different temperatures, three experimental

l6 BULLETIN NO. 646, TEXAS AGRICULTURAL EXPERIMENT STATION

lots of cheese were prepared by using 2, 4 and 8 ounces of rennet extract
per 1000 pounds of milk. The moisture content was controlled such that the
percentage moisture in all the lots of the finished cheese was practically the
same. The cheese was paraffined and ripened at the temperatures of 45',
60°, 70° and 80°F. for 12 Weeks. Flavor, body and texture, ripening observa-
tions and protein hydrolysis determinations were made at the end of the
ripening period.

Effect of Stirred Curd and Cheddar Methods of Manufacture
- Upon the Rate of Ripening

A comparison of the effect of the stirred curd and cheddar methods of
manufacture upon the rate of ripening was made by preparing two experi-
mental lots of cheese from identical milk. One lot was made by the cheddar
method and the other by the stirred curd method. The cheese was sealed
in cans and ripened at 45°, 60°, 70° and 80°Fahrenheit. Flavor, body and
texture, and ripening observations were made when the cheese had oured 8
weeks and again at 16 weeks.

Effect of High Acidity and Washing Treatment of the Curd
Upon Rate of Ripening

To determine the effect of high acidity and washing treatments of the
curd upon the rate of ripening of cheese, three lots of milk were made into
cheese. In each lot one-half of the milk was ripened in order to make a
cheese with an acidity of pH 5.0, and the other half of the milk was made
such that the acidity of the cheese was pH 5.5. After the curds were milled,
each was divided into three portions. One portion was washed with cold
water (50°F.) for 15 minutes, thereby lowering the temperature of the curd
to 67 °Fahrenheit. The second portion was pasteurized with hot water for
30 minutes at the temperature of 145° to 150°F. and then cooled to 90°Fah-
renheit. The third lot was not treated and was used as a control. Flavor,
body and texture and ripening observations were made at the end of a 4
weeks period.

RESULTS

Of the several treatments used in the preliminary investigation, varia-
tions in the ripening temperature seemed most effective in influencing the
quality of short cure cheese. Large amounts of rennet and washing the
ourd ‘encouraged the breakdown of the body, but they were not effective in
the development of flavor. The results of a more detailed study of these
factors are shown.

Effect of Various Ripening Temperatures Upon the Rate of Ripening

The 13 lots of cheese used in this investigation were divided into six
experimental groups to determine the effect of various treatments upon
the quality and rate of ripening.

Experimental Groups
Group I —Ripened at 45°, 60°, 70° or 8-0°F. for periods of 2, 4, 8 or 16
weeks.

Group II —Ripened at 45°F. for 2 weeks plus 2 or 6 weeks periods at 60°,
l 70° or 80°F.

Group III-—Ripened at 45°F. for 4 weeks plus 4 weeks at 60°, 70° or 80°F.

FACTORS AFFECTING THE QUALITY OF SOUTHERN CHEDDAR CHEESE 17

Group IV-—Ripened at 45°F. for 2 weeks plus 6 weeks at 60°, 70° or 80°F.
plus 8 weeks at 45°F.

Group V —Ripened at 45°F. for 4 weeks plus 4 weeks at 60°, 70° or 80°F.
plus 8 weeks at 45°F.

Group VI-—Ripened at 60°, 70° or 8-0°F. for 8 Weeks plus 8 Weeks at 45°F.

The effect of ripening temperatures upon the pH value, moisture con-
tent and the firmness of body of the different lots of cheese used in this
investigation is shown in Table 5.

Table 5. The effect of various ripening treatments upon the pH, moisture content and
firmness of the ripened cheese

Moisture Hardness

Ripening Treatment pH Per Cent Grams
1 day of age 5.32 37.4 —
Group I
2 wks. at 45°F. 5.27 37.8 553
4 wks. at 45°F. 5.30 37.4 568
8 wks. at 45°F. 5.34 37.2 571
16 wks. at 45°F. 5.57 36.7 474*
2 wks. at 60°F. 5.24 37.5 563
4 wks. at 60°F. 5.32 37.4 589
8 wks. at 60°F. 5.28 37.4 582
16 wks. at 60°F. 5.64 36.5 592
2 wks. at 70°F. 5.22 37.4 559
4 wks. at 70°F. 5.28 37.1 581
8 wks. at 70°F. 5.35 36.3 586
16 wks. at 70°F. 5.75 36.5 649
2 wks. at 80°F. 5.21 37.2 621
4 wks. if.‘ 80°F. 5.32 37.2 705
8 wks.. at 80°F. 5.39 36.4 729
16 wks. at 80°F. 5.58 36.2 702
Group II
2 wks. at 45°F. plus 2 wks. at 60°F. 5.25 37.3 549
2 wks. at 45°F. plus 2 wks. at 70°F. 5.25 37.4 529
2 wks. at 45°F. plus 2 wks. at 80°F. 5.27 37.2 590
2 wks. at 45°F. plus 6 wks. at 60°F. 5.30 36.8 546
2 wks. at 45°F. plus 6 wks. at 70°F. 5.32 36.9 557
2 wks. at 45°F. plus 6 wks. at 80°F. 5.41 36.6 672
. GroupIII
4 wks. at 45°F. plus 4 wks. at 60°F. 5.29 38.1 524
4 wks. at 45°F. plus 4 wks. at 70°F. 5.28 37.0 526
4 wks. at 45°F. plus 4 wks. at 80°F. 5 30 37.1 569
Group IV
2 wks. at‘ 45°F. plus 6 wks. at 60°F. plus 8 wks. at 45°F. 5.67 37.5 515
2 wks. at 45°F. plus 6 wks. at 70°F. plus 8 wks. at 45°F. 5.61 37.3 552*
2 wks. at 45°F. plus 6 wks. at 80°F. plus 8 wks. at 45°F. 5 65 37.5 596
Group V

4 wks. at 45°F. plus 4 wks. at 60°F. plus 8 wks. at 45°F. 5.62 37.2 483
4 wks. at 45°F. plus 4 wks. at 70°F. plus 8 wks. at 45°F. 5.59 37.0 499
4 wks. at 45°F. plus 4 wks. at 80°F. plus 8 wks. at 45°F. 5.51 37.9 567

Group VI
8 wks. at 60°F. plus 8 wks. at 45°F. 5. .1 513*
8 wks. at 70°F. pl-us 8 wks. at 45°F. 5.85 37.3 562
8 wks. at 80°F. plus 8 wks. at‘ 45°F. 5. .9 684

‘iOutstandingly desirable body.

The pH of the cheese increased slightly with age, but the tempera-
ture of curing appeared to have no appreciable effect upon the rate of
change. The decrease in moisture due to the increase in ripening tem-
perature was so slight it is doubtful that it affected the quality of the
cheese or rate of curing.

18

The body of the cheese increased in firmness with the higher ripe

BULLETIN  646, TEXAS AGRICULTURAL EXPERIMENT STATION

temperature. It also increased as the time of curing increased except u“

the lots of cheese ripened at 45°

F. for 16 weeks.

A comparison of the hardness values with the body scores indica Y,
that a value of approximately 525 grams was associated with the ~~rf

desirable body. A relationship between the hardness value and the bo

score did not exist in all cases; however, cheese with hardness values F

siderably higher than 525 grams received low body scores. Cheese wi

a hardness value as high as 700 grams usually had a rubbery, dry oli

crumbly body, and cheese with a hardness value of less than 400

could be expected to have a soft pasty body.

The detail scores and ripening observations of the various lots

cheese are presented in Table 6.

gra tit)

Table 6. The effect of various ripening treatments upon the quality of ripened cheese

Total Flavor Body and Degree of 
Ripening Treatment Score Score Texture Score Ripenesl 
GROUP 1 
4 wks. at 45°F. 89.2 23.1 (acceptable) 36.1 (acceptable) Inferior 
8 wks. at 45°F. 89.5 23.3 (acceptable) 36.2 (acceptable) Inferior 
*16 wks. at 45°F. 91.8 23.7 (acceptable) 38.1 (good) Acceptable;
4 wks. at 60°F. 89.5 23.1 (acceptable) 36.4 (acceptable) Inferior 
8 wks. at 60°F. 89.6 23.4 (acceptable) 36.2 (acceptable) Acceptable»!
*16 wks. at 60°F. 91.4 23.5 (acceptable) 37.9 (good) Good _
4 wks. at 70°F. 89.1 23.3 (acceptable) 35.8 (inferior) Acceptable?
8 wks. at 70°F. 89.3 23.4 (acceptable) 35.9 (inferior) Acceptable.
*16 wks. at 70°F. 90.8 23.5 (acceptable) 37.3 (good) o0 
4 wks. at 80°F. 88.8 23.5 (acceptable) 35.3 (inferior) Acceptable,‘
8 wks. at 80°F. 86.9 22.6 (inferior) 34.3 (inferior) Good "
16 wks. at 80°F. 88.4 21.7 (inferior) 36.7 (acceptable) Excellent
GROUP II
*2 wks. at 45°F. plus 2 wks. at 60°F. 89.5 23.1 (acceptable) 36.4 (acceptable) Good
2 wks. at 45°F. plus 2 wks. at 70°F. 89.5 23.3 (acceptable) 36.2 (acceptable) Acceptable
2 wks. at 45°F. plus 2 wks. at 80°F. 89.5 23.7 (acceptable) 35.8 (inferior) Acceptable
2 wks. at 45°F. plus 6 wks. at 60°F. 89.8 23.6 (acceptable) 36.2 (acceptable) Acceptable .4
*2 wks. at 45°F. plus 6 wks. at 70°F. 89.7 23.6 (acceptable) 36.1 (acceptable) Good '
2 wks. at 45°F. plus 6 wks. at 80°F. 86.6 22.2 (inferior) 34.4 (inferior) Good
GROUP III
4 wks. at 45°F. plus 4 wks. at 60°F. 89.5 23.3 (acceptable) 36.2 (acceptable) Acceptable
*4 wks. at 45°F. plus 4 wks. at 70°F. 89.6 23.5 (acceptable) 36.1 (acceptable) Acceptable
4 wks. at 45°F. plus 4 wks. at 80°F. 88.9 23.3 (acceptable) 35.6 (inferior) Acceptable
GROUP IV
2 wks. at 45° plus 6 wks. at 60°F.
plus 8 wks. at 45°F. ' 91.1 23.7 (acceptable) 37.4 (good) Good
*2 wks. at 45°F. plus 6 wks. at 70°F.
plus 8 wks. at 45°F. 91.9 23.8 (acceptable) 38.1 (good) Good
2 wks. at 45°F. plus 6 wks. at 80°F.
plus 8 wks. at 45°F. 90.2 23.4 (acceptable) 36.8 (acceptable) Good
GROUP V
4 wks. at 45°F. plus 4 wks. at 60°F.
plus 8 wks. at 45°F. 91.0 23.8 (acceptable) 37.2 (good) Good
*4 wks. at 45° plus 4 wks. at 70°F.
plus 8 wks. at 45°F. 91.6 24.1 (good) 37.5 (good) Good
4 wks. at 45°F. plus 4 wks. at 80°F.
plus 8 wks. at 45°F. . 90.4 23.5 (acceptable) 36.9 (acceptable) Good
GROUP VI
*8 wks. at 60°F. plus 8 wks. at 45°F. 92.3 24.0 (good) 38.3 (good) Good
8 wks. at 70°F. plus 8 wks. at 45°F. 90.4 23.4 (acceptable) 37.0 (good) Good
8 wks. at 80°F. plus 8 wks. at 45°F. 88.9 22.5 (inferior) 36.4 (acceptable) Excellent

*Outstandingly desirable cheese.

_.

w

FACTORS AFFECTING THE QUALITY OF SOUTHERN CHEDDAR CHEESE 19

The score values given in Table 6 show that the cheese ripened by the
combination of 8 weeks at 60°F. and 8 weeks at 45°F. was probably the
best as it had the highest total score value and was superior in body and
texture. The cheese ripened for 4 weeks at 45°F. plus 4 weeks at 70°F.
and 8 weeks at 45°F. was superior in flavor, and the cheese ripened at
80°F. for 16 weeks was rated best in degree of ripning. With the tem-
peratures of 45°, 60° and 70°F., the flavor, body and total score values in-
creased as the ripening time was prolonged. The prolonged ripening time
had a greater effect upon the body score than upon the flavor score.

The additional holding period of 8 weeks at 45°F. was more effective
in improving the body and texture and ripening than in improving the
flavor score. After an 8~ weeks storage period at 45°F. the cheese ripened
at 70°F. was considered the best. Although there was little differ-
ence in the flavor and body scores of the cheese ripened at 60° and
70°F., the cheese ripened at 70°F. ripened much faster. The cheese
ripened at 45°F. was superior in body score but was slow in ripening and
flavor development, and the cheese held at 80°F. ripened faster but was
inferior in body score. Cheese held at 80°F. for any length of time re-
ceived a lower flavor, body and total score than cheese held at any other
ripening temperature. Ripening observations indicate that the degree of
ripening increased as the temperature increased.

In general, cheese ripened at 45°F. for the entire ripening period was
lacking in flavor development, had a tough rubbery body and lacked ripe-
ness. Cheese ripened at 60°F. was slightly lacking in flavor, had a
somewhat firm body, but had desirable ripening qualities. The cheese
ripened at 70°F. was full in flavor, but had a weak and slightly crumbly
body defect. Cheese held at 80°F. received a lower score because it pos-
sessed unnatural flavors and had a weak, crumbly, sticky body, but was
usually fully ripened.

In determining the best ripening treatment for the production of the
nighest quality short cure cheese, it seems that the most desirable cheese
produced within a 4 weeks curing period was the cheese held 2 weeks at
45°F. and 2 weeks at 60°Fahrenheit. The cheese held 2 weeks at 45°F.
and 2 weeks at 70°F. was almost equally as good except its ripening con-
dition was less satisfactory. The most desirable cheese produced in an 8
weeks ripening period was that held 2 weeks at 45°F. and 6 weeks at
60°Fahrenheit. The cheese held 8 weeks at 60°F. was somewhat lower in
score value at the end of an 8 weeks period, but after an additional 8
weeks storage period at 45°F., it developed into a higher scoring cheese.
These results indicate that, by the use of the proper ripening treatment, a
cheese of desirable quality can be produced for marketing within a 4 to 8
weeks period.

Table 7 shows a detailed analysis of the protein hydrolysis and the
distribution of the different fractions of nitrogen at various intervals
during ripening.

20 BULLETIN NO. 646, TEXAS AGRICULTURAL EXPERIMENT STATION

Table 7. The effect of various ripening treatments upon protein hydrolysis and
the nitrogen distribution

Water _Soluble N not
water precipitated by
, _ ~ Total Soluble Trichlo- Tannic Phospho-
Rlpenmg Treatment Nitrogen Nitrogen racetic acid- tungstic
acid salt acid
per cent per cent per cent per cent per cent
1 day old 3.3 4.9 3.8 6.0 1.0
GROUP I
2 Wks. at 45°F. 3.5 12.4 9.3 5.3 1.7
4 Wks. at 45°F. 3.6 16.0 12.0 4.0 2.6
8 wks. at 45°F. 3.6 18.6 13.4 5.1 3.2
“.16 Wks. at 45°F. 3.6 25.5 20.2 8.0 6.0
2 wks. at 60°F. 3.5 15.2 11.6 6.3 2.3
4 wks. at 60°F. 3.6 20.5 15.1 5.3 4.1
8 Wks. at 60°F. 3.6 26.2 21.0 9.1 6.4
*16 Wks. at 60°F. 3.6 39.6 36.3 21.0 17.1
2 wks. at 70°F. 3.6 17.1 14.1 7.1 3.2
4 Wks. at 70°F. 3.6 23.6 19.3 7.9 5.4
8 wks. at 70°F. 3.6 30.5 26.0 12.4 9.3
*16 wks. at 70°F. 3.6 41.9 37.7 24.3 21.3
2 wks. at 80°F. 3.6 19.6 16.4 7.8 4.1
4 wks. at 80°F. 3.6 26.8 22.8 12.3 7.6
8 Wks. at 80°F. 3.6 33.1 29.0 16.5 12.6
1.6 Wks. at 80°F. 3.7 44.1 41.4 29.9 24.9
GROUP II
*2 wks. at‘ 45°F. plus 2 wks. at 60°F. 3.6 18.0 13.9 5.0 3.3
2 Wks. at 45°F. plus 2 wks. at 70°F 3.6 21.2 17.4 6.5 4.3
2 wks. at 45°F. plus 2 wks. at 80°F 3.6 24.9 19.3 7.4 8.0
2 wks. at 45°F. plus 6 Wks. at 60°F 3.6 26.2 20.4 8.4 6.2
*2 wks. at 45°F. plus 6 wks. at 70°F 3.6 29.2 24.2 10.4 7.8
2 wks. at 45°F. plus 6 wks. at 80°F 3.6 33.9 30.3 14.9 11.8
GROUP III
4 wks. at 45°F. plus 4 wks. at 60°F 3.5 25.4 19.1 8.6 5.5
*4 wks. at 45°F. plus 4 wks. at 70°F 3.6 27.0 21.2 8.4 6.4
4 Wks. at 45°F. plus 4 Wks. at 80°F 3.6 30.2 24.5 10.0 8.2
GROUP IV

2 wks. at 45°F. plus 6 wks. at 60°F.
plus 8 wks. at 45°F. 3.5 32.2 26.9 12.3 9.2

*2 wks. at 45°F plus 6 wks. at 70°F.
plus 8 Wks. at 45°F. 3.6 33.9 29.9 14.9 11.4

2 wks. at 45°F. plus 6 wks. at 80°F.
plus 8 wks. at 45°F. 3.6 35.9 32.8 17.5 13.1

GROUP V

4 wks. at 45°F. plus 4 wks. at 60°F.
plus 8 Wks. at 45°F. 3.6 30.8 25.6 11.5 8.4

*4 wks. at 45°F. plus 4 wks. at 70°F.
plus 8 Wks. at‘ 45°F. 3.6 32.6 27.3 12.1 9.4

4 wks. at 45°F. plus 4 wks. at 80°F.
plus 8 wks. at 45°F. 3.6 36.8 32.3 15.6 11.9

GROUP VI

*8 wks. at 60°F. plus 8 wks. at 45°F. 3 6 20.5 26.4 12.9 9.8
8 wks. at 70°F. plus 8 wks. at 45°F. 3.6 ‘5.6 31.5 17.0 12.8
8 wks. at 80°F. plus 8 wks. at 45°F. 3.6 36.0 33.7 19.8 15.6

'*Outstandingly desirable cheese.

Table 7 shows that the rate of production of water soluble nitrogen
and the water soluble nitrogen not precipitated by trichloracetic acid was
very similar. The rate was greatest in the first part of the period for all
lots. In each of those lots which was held at 50°, 60°, 70° and 80°F. for
the entire 16 weeks period, the rate of production was quite uniform after
the fourth week. The differencein amount of Water soluble nitrogen and
the trichloracetic acid fraction produced between the 45° and 60°F. ripen-
ing temperatures was much greater than the difference between the tem-

 

FACTORS AFFECTING THE QUALITY OF SOUTHERN GHEDDAR CHEESE 21

peratures of 60° and 70°F. or between 70° and 80°Fahrenheit. The amount
of water soluble nitrogen present at the end of the fourth week of ripen-
ing was 16.0, 20.5, 23.6 and 26.8 per cent, and the amount of water soluble
nitrogen not precipitated by trichloracetic acid at the end of the ripening
period was 12.0, 15.1, 19.3 and 22.8 per cent at ripening temperatures of
45°, 60°, 70° and 80°F., respectively.

The tannic acid-salt fraction and the phosphotungstic acid fraction did
not show the rapid rate of increase in the early part of the ripening
period that was shown in the water soluble nitrogen and the trichloracetic
acid fraction. The tannic acid-salt fraction was higher in every case than
the phosphotungstic acid fraction. The percentage of the tannic acid-salt
fraction at the end of the fourth week of ripening was 4.0, 5.3, 7.9 and 12.3,
and the percentage of the phosphotungstic acid fraction was 2.6, 4.1, 5.4
and 7.6 at the ripening temperatures of 45°, 60°, 70° and 80°F., re-
spectively.

The rate of hydrolysis of cheese held at 45°F. was more uniform
throughout the 16 weeks ripening period; whereas, that of cheese held at
the 60°, 70° and 80°F. showed uniform hydrolysis for 4 weeks after
which there was considerable increase in the rate of protein decomposition.
The rate and amount of hydrolysis decreased as the ripening temperature
decreased; it was greatest at 80°F., followed in order by 70°, 60° and
45°Fahrenheit. The rate of hydrolysis increased when the cheese was
moved from 45°F. to any of the higher temperatures. The increase being
greater at the higher temperatures. Protein hydrolysis was checked by
moving the cheese from the higher temperatures to the 45°F. ripening
temperature. No specific relationship could be established between the
various nitrogen fractions and the quality of the cheese except that the
score value increased as the amount of proteolysis increased. Excessive
proteolysis, however, resulted in lower score values.

Effect of the Amount of Rennet Extract Upon Quality and Rate
of Ripening at Various Temperatures

The effect of 2, 4 and 8 ounces of rennet extract per 1000 pounds of
milk upon the quality of cheese ripened at various temperatures for a 12
week period is given in Table 8.

The results indicate that the cheese made using 8 ounces of rennet per
1000 pounds of milk was superior at all ripening temperatures in ‘flavor
and condition of ripening. The cheese made using 4 ounces of rennet per
1000 pounds of milk was superior in body and texture score. The use of
only 2 ounces of rennet per 1000 pounds of milk produced a slow ripening
cheese at all of the temperatures studied. The results suggest that the
amount of rennet used is an important factor in producing a short cure
cheese. The use of 8 ounces of rennet per 1000 pounds of milk produced
a cheese with superior flavor and ripening qualities, but the body of this
cheese was weak and sticky. Therefore, the use of 8 ounces of rennet per
1000 pounds of milk cannot be recommended to give better results than 4
ounces of rennet per 1000 pounds of milk in the production of a short cure
cheese.

22

BULLETIN NO. 646, TEXAS AGRICULTURAL EXPERIMENT STATION

Table 8. The effect of the amount of rennet extract upon the quality of cheese ripened at
various temperatures for 12 weeks

Ripening Ounces of rennet Body and Degree
temperatures extract per 1000 Flavor texture _ 0f
degrees F. lbs. milk score ’__V_s_co_rgg_ ripeness
23.5 35.7
2 (acceptable) (inferior) Inferior
23.5 37.2
F 45 4 (acceptable) (good) Inferior
24.0 36.7
8 (good) (acceptable) Acceptable
23.5 ' 35.7
2 (acceptable) (inferior) Inferior
23.7 37.0
_ . 60 4 (acceptable) (good) ACCQDtBbIE
24.2 36.7
8 (good) (acceptable) Good
23.7 35.5
2 (acceptable) (inferior) Inferior
24.0 37.5
7 0 4 (good) (good) Good
24.7 36.5
8 (good) (acceptable) Good
___________
23.7 34.2
2 (acceptable) (inferior) Inferior
24.2 36.9
30 4 (good) (acceptable) Acceptable
. 24.7 36.2
8 (good) (acceptable) Good

Table 9. Effect of the amount of rennet extract upon protein hydrolysis of cheese ripened
at various temperatures for 12 weeks

Water soluble N
Ripening Rennet extract Water precipitated by .
tempera- per 1000 lbs. soluble Trichl0- Phospho- Mmsmre
tures of milk nitrogen racetic tungstic
acid acid
degrees F. ounces per cent per cent per cent ‘ per cent
2 10.4 8.4 3.9 35.8
45 4 13.7 8.4 3.2 34.7
8 16.3 9.7 2.7 34.4
2 17.9 15.3 5.1 34.5
60 4 20.8 12.8 6.4 33.3
8 22.2 17.2 5.5 33.0
2 17.9 16.5 6.7 32.7
70 4 22.4 16.1 8.1 31.2
8 26.5 19.5 7.7 31.3
2 19.1 17.2 7.5 30.3
80 4 25.7 18.8 8.4 31.3
8 26.3 20.8 8.2 32.4

23

FACTORS AFFECTING THE QUALITY OF SOUTHERN CHEDDAR CHEESE

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24 BULLETIN NO. 646, TEXAS AGRICULTURAL EXPERIMENT STATION

In order to determine the effect of the amount of rennet extract upon l
protein hydrolysis, a detailed chemical analysis was made of the various t
nitrogen soluble fractions of cheese manufactured with different amounts ;
of rennet and ripened at various temperatures for a period of 12 weeks. i

The results are shown in Table 9.

The- amount of protein hydrolysis increased with additional amounts l‘
of rennet extract and also with the increase in temperature. From the it
figures in Table 9, calculations can be made to show that by using 8 3

ounces instead of 2 ounces of rennet extract per 1000 pounds of milk the

water soluble nitrogen was increased 57 per cent in cheese ripened at it
At temperatures of 60°, 70° and 80°F., this increase was i

45°Fahrenheit.
24, 48 and 38 per cent, respectively.

In those lots containing 4 ounc s of rennet per 1000 pounds of milk, 0'

the cheese ripened at 60°F. showed 51 per cent more water soluble nitro-

gen than cheese ripened at 45°F., but the increase of the water soluble ni- ‘

trogen of the cheese ripened at 70°F. was only 10 per cent greater than

that at 6OF., and the increase in the cheese ripened at 80°F. was only 7 i
These percentages indi- a
cate that protein hydrolysis was affected to the greatest extent between l
the temperatures of 45° and 60°F., and that additional amounts of rennet '
extract brought about more rapid protein hydrolysis at all temperatures A‘

per cent above that ripened at 70°Fahrenheit.

studied.

Effect of Stirred Curd and Cheddar Methods Upon the Rate of Ripening

The average flavor and body scores and ripening observations of

cheese made by the stirred curd and cheddar methods after 8i and 16’ i

weeks of ripening are recorded in Table 10.

It can be seen that the stirred curd cheese was better than the ched-
dar cheese at the end of an 8 weeks period. The highest flavor score was
given to the stirred curd cheese ripened at 80°Fahrenheit. The stirred
curd cheese also was usually superior in body score at the end of the 8
weeks curing period. However, after 16 weeks of ripening, the cheese
made by the cheddar method had higher flavor and body scores. There
was an indication that the stirred curd cheese ripened faster but did not
reach as high a maximum score over a long curing period.

A more detailed analysis of the ripening properties of the cheese
manufactured by the two methods is presented in Table 11.

In summarizing the results presented in Table 11, it can be seen that
cheese made by the cheddar method retained a greater amount of water
during ripening and had a somewhat firmer body than the stirred curd
type cheese except at the 80°F. ripening temperature.

The stirred curd cheese was highest in protein derived products at nearly
every interval during the ripening process. This indicates that protein
hydrolysis was more rapid in the stirred curd cheese, and that this method
might be of value for use in the production of a rapid curing cheese under
special conditions.

~a

25

FACTORS AFFECTING THE QUALITY OF SOUTHERN CHEDDAR CHEESE

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26 BULLETIN NO. 646, TEXAS AGRICULTURAL EXPERIMENT STATION

‘The Effect of High Acidity and 0f Washing the Curd Upon
the Quality of Cheese

The effect of acidity and various curd treatments upon the quality of i

cheese at the end of a 4 weeks ripening period is shown in Table 12.

The control, washed curd, and pasteurized curd lots of the high acid z

cheese (pH 5.0) were poorer in flavor than their paired lots of the normal
acid cheese (pH 5.5). The control lots of the high acid cheese decreased in
flavor score as the ripening temperature increased. The washed curd lots re-
ceived the best flavor scores of the high acid cheese. The control lots were
better in flavor than the pasteurized curd lots when ripened at 45° and
60°F., but the reverse was true at the temperatures of 70° and 80° Fahren-
heit. In the normal acid cheese, the washed curd lots were best in flavor.

According to the average body score, the control and washed curd lots
of high acid cheese were better than their paired lots of normal acid cheese
at the temperatures of 45° and 60°F., but at temperatures of 70° and 80°F.
the reverse was true. The pasteurized curd lots of the high acidity cheese
were better than the corresponding lots of normal acid cheese. In both the
high acid and normal acid cheese the washed curd lots were superior in body
score. The curd treatments studied appear to be of little value in increasing
the quality of cheese during a four weeks ripening period.

The influence of different curd treatments during the manufacturing
process upon the analysis and nitrogen distribution of cheese after a 4
weeks ripening period at various temperatures is shown in Table 13.

The amount of hydrolysis was greater in the high acid lots of cheese
than in the normal lots of cheese. Pasteurization of the curd retarded
protein hydrolysis at the lower temperatures, but this effect was not as
pronounced at the higher ripening temperatures. The washed curd cheese
in both the high and normal groups of cheese had somewhat greater pro-
tein hydrolysis.

DISCUSSION

The results of the preliminary investigation indicated that the use of
large amounts of rennet and the washed curd treatment proved most ef-
fective in producing a cheese with a superior body. The temperature at
which the cheese was ripened was of ultimate importance in influencing the
rate of flavor development and the score of the cheese. The amount of ren-
net used was an important factor in the production of a short cure cheese,
as additional amounts of rennet extract, up to as much as eight ounces per
1000 pounds of milk produced more rapid ripening and increased the score
value of the cheese at ripening temperatures as high as 70°Fahrenheit.
Cheese manufactured by the stirred curd method ripened more rapidly than
did the cheese manufactured by the regular cheddar method. The stirred curd
method may have some value in the manufacture of a rapid cure cheese but
cheese made by this method did not reach as high a maximum score as did
cheese made by the cheddar method. There was no advantage obtained by
developing a higher acidity during the manufacturing process; however,
washing the curd improved the quality of the cheese and increased the rate
of ripening. Perhaps the desirable conditions secured by the use of the
stirred curd method and by washing the curd were the results of a reduced
acidity of the cheese at the time of pressing and in some cases a somewhat
higher moisture content of the cheese. Both of these factors encourage in-
creased bacterial action and more rapid ripening.

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FACTORS AFFECTING THE QUALITY OF SOUTHERN CHEDDAR CHEESE

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28 BULLETIN NO. 646, TEXAS AGRICULTURAL EXPERIMENT STATION

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FACTORS AFFECTING THE QUALITY OF SOUTHERN CHEDDAR CHEESE 29

The ripening temperature was increased to a maximum of 70°F. with
desirable results. The rate of flavor development was greatly increased by
raising the ripening temperature; however, a prolonged ripening time was
necessary to secure a high body score. The rate of ripening had a direc-t ef-
fect upon the quality of the cheese. Ripening time was greatly decreased at
higher temperatures and in many cases high rates of proteolysis resulted in
cheese of corresponding lower score values. When cheese was ripened for 4,
8 and 16 weeks periods, the highest scoring cheese for each period was that
ripened at 60°F. and 70°F. plus an initial storage period at 45°Fahrenheit.
Cheese ripened at 80°F. was inferior in most cases. In the production of a

ishort cure cheese a ripening period at a higher temperature for flavor was

desirable, and an additional storage period was beneficial to body develop-
ment. Of all the factors studied, the temperature of ripening and the
amount of rennet used seemed most important in the production of a short
cure cheese.

The results of this investigation indicate that a high score short cure
cheese can be produced for marketing within a four weeks period by using
4 ounces of rennet per 1000 pounds of milk and by holding the cheese at
60°F. during a portion of the ripening period. As much as 8 ounces of
rennet per 1000 pounds of milk gave desirable results except at tempera-
tures as high as 80°Fahrenheit. The best cheese produced within a four
weeks period was ripened for two weeks at 45°F. and two weeks at 60°Fah-
renheit. The best cheese produced within an eight weeks period was ripened
two weeks at 45°F. and six weeks at 60°Fahrnheit.

CONCLUSIONS

1. A detailed study of the effect of ripening temperature upon
the quality of short cure cheese showed that the temperature
of 60°F. gave the most desirable results, and that temperatures
as high as 70°F. could be used with satisfactory results.

2. The rate of proteolysis was greatly increased by ripening
temperature.

3. Proteolysis was checked by moving cheese from higher tem-
peratures to a storage temperature of 45°Fahrenheit.

4. When 2, 4 and 8 ounces of rennet extract were used per 1000
pounds of milk, it was found that the 4 ounce quantity gave
the most desirable results and that as much as 8 ounces of
rennlet per 1000 pounds of milk could be used with satisfactory
resu ts. '

5. When 2, 4 and 8 ounces of rennet extract were used per 1000
pounds of milk, the rate of proteolysis increased with each
additional increment of rennet at all ripening temperatures.

6. There was an indication that stirred curd cheese ripened fast-
er but did not reach as high a maximum score as did cheese
made by the cheddar method.

7. There was no advantage obtained in rate of ripening and
quality of cheese by developing a higher acidity during the
cheese manufacturing process.

8. The results of this investigation are significant in that they
indicate that a high score short cure cheese can be produced
for marketing within a four weeks period, by using 4 ounces
of rennet extract per 1000 pounds of milk and by holding the
cheese at a temperature of 60° to 70°F. during a portion of
the ripening period.

10.

11.

12.

13.

14.

15.

16.

18.

19.

20.

21.

22.

23.

BULLETIN NO. 646, TEXAS AGRICULTURAL EXPERIMENT STATION

LITERATURE CITED

Association of Official Agricultural Chemists.
1935. Official and Tentative Methods of Analysis,
4th ed. Assoc. Off. Agr. Chem. Washington, D. C.
Allen, L. A.
1930. Studies in the Ripening of Cheddar Cheese.
Jour. Dairy Res. 2:38-67.
Atkinson, T. H.
1924. Temperature 0f the Cheese Curing Room.
Agr. Gaz. N. S. Wales. 35: 649-652.
Babcock, S. M., Russell, H. L., and Vivian, A.
1900. Influence of Rennet 0n Cheese Ripening.
17th Ann. Rpt‘. Wis. Agr. Exp. Sta.
Bartel, C., Sandberg, E. and Haglund, E

1928. Une Nowelle Methode pour YEtude du Procide de la Maturation des Formages-

Le Lait 8: 285-288.
Doane. C. F.
1906. Investigations in the Manufacture and Curing of Cheese. VI. The Cold Curing
of American Cheese.
U. S. Dept. Agr., Bur. An. Ind. Bul. 85.
Doane, C. F., Aderhold, E. L., and Wilson, H. L.
1940. Fifty Years of Cheesemaking—-Acidity Development.
Nat. Butter and Cheese Jour. 31 :5.
Freeman, T. R.
1938. Rate of Ripemng in Cheddar Cheese.
Penn. Agr. Exp. Sta., Bul. 362.
Haglund, E., Bartel, C., and Sandberg, E.
1926. The Number of Bacteria in Milk for Cheesemaking and the Rapidity of Ripen-
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(Abstract) Le Lait 6:31.
Harding, H. A.
1903. The Role of Lactic-Acid Bacteria in the Manufacture and in the Early Stages
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N. Y. (Geneva) Agr. Exp. Sta. Bul. 237.
Marquardt. J. C.

1936. The Salting and Cooking of Curds in the Manufacture of Several Varieties of
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N. Y. (Geneva) Agr. Exp. Sta. Bul. 670.
Menefee, S. G., and Overman, O. R.
1940. 1A1 Semimicro-Kjeldahl Method for the Determination of Total Nitrogen in
ilk.
Jour. Dairy Sci., 23: 1177-1185.
Phillips. C. A.

1936. Acidity Control in the Manufacture and_Curing of Cheese. Proc. 22nd. Ann.

Meeting Amer. Dairy Sci. Assoc. West DIV.
Price, Walter V.
1936. Bitter Flavor in Cheddar Cheese.
Jour. Dairy Sci. 19: 185-190.
Riddet, W., et al.
1933. The Effect of Salt Upon the Quality of Cheddar Cheese.
Massey Agr. Col.: Bul. N0. 32 Palmerston North, New Zealand.
Sammis, J. L.
1923. Quick Curing Cheese. How It Should Be Made and Under What Conditions.
N. Y. Prod. Rev. and Am. Cry. 57: 147.
Sherwood, I. R.
1935. The Function of Pepsin and Rennet in the Ripening of Cheddar Cheese.
Jour. Dairy Res. 6: 407-421.
Smith, G. A.
1900. The Influence of the Temperature of Curing Upon the Commercial Quality
of Cheese. N. Y. (Geneva) Agr. Exp. Sta. Bul. 184.
Townsend, C. T.
1925. Action of Rennet on Paracasein.
Van Slyke, L. L., and Hart, E. B.
1903. Conditions Affecting Chwnical Changes in Cheese-ripening. N. Y. (Geneva)
Agr. Exp. Sta. Bul. 236.
Van Slyke, L. L., and Price, Walter V.
1941. Cheese. Orange Judd Publishing Co., Inc., New York—~Page 287.
Van Slyke, L. L., Smith, G. A., and Hart, E. B.
1903. Experiments in Curing Cheese at Different Temperatures.
Agr. Exp. Sta. Bul. 234.
Wojtkiewicz, A. F., and Inikkoff.
1934. U.S.S.R. The Acceleration of the Ripening of Cheese.
Tenth World's Dairy Congr. II Section: 335-339.

Sci. Agri. '6: 158-164.

N. Y. (Geneva)

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