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Thomas Nelson Biumer
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THEMS

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CHEMICAL COMPOUNDS ASSOCIATED

WITH AGED HAM FLAVOR

BY

Thomas Nelson Blumer

A Thesis

Submitted to the School of Graduate Studies of Michigan State College
of Agriculture and Applied Science in partial fulfillment
of the requirements for the degree of

DOCTOR OF PHILOSOPHY

Department of Food Technology

1954

ACKNOWLEDGEMEN TS

The author wishes to express his sincere appreciation to
Dr. C. L. Bedford and Dr. R. E. Marshall for their interest,
advice, and kind assistance during the entire graduate program.

He also wishes to express his deep gratitude to Professor
L. J. Bratzler for his helpfulness and friendly interest in all
phases of the program.

The writer is deeply indebted to Professor F. H. Smith and
Dr. S. B. Tove for their help and suggestions in regard to the
chemical aspects of the thesis study.

Grateful acknowledgement is made to Mrs. Eleanor Gates for
her assistance in the collection of the data.

The investigator gratefully appreciates the interest, inspira-
tion and friendly council of Dr. J. L. Etchells throughout the entire
graduate program.

He is also indebted to Dr. W. L. Mallman for his interest and
cooperation.

The author expresses his appreciation to Professor E. H.
Hostetler, Dr. H. A. Stewart and others in administrative positions
who have been generous and tolerant in permitting the use of

facilities and time necessary in pursuing graduate studies.

The writer is grateful for the assistance and advice of
Dr. R. J. Monroe, Dr. H. L. Lucas and Dr. W. W. G. Smart, Jr.

in the statistical aspects of the collection and analysis of data.

TABLE OF CONTENTS

Introduction

Historical Review
Experimental Procedure
Analytical Procedure
Results

Discussion of Results
Summary

Bibliography

Page

23
31
35
55

63

LIST OF TAB LES

Table Page
I Taste Panel Score 36
II Moisture, Fat and Salt (fresh basis) Analysis 39
III Peroxides, Free Fatty Acids and Iodine Number
Analysis 41
IV Chloride, Soluble Nitrogen and Total Nitrogen
Analysis 43
V pH, Lactic Acid and Glucose Analysis 44
VI Glycerol and Organic Matter Analysis 45
VII Unsaturated Fatty Acids 48
VIII Milliequivalents of Short Chain Fatty Acids per

Gram of Ham 5 0

IX Statistical Analysis of the Differences of Test

Factors at Progressive Storage Periods 53
X Correlation Coefficients for Test Factors 54
LIST OF FIGURES
Figure Page

1 Sample Score Sheet - Taste Test Evaluation 29

IN TR ODU CTION

Previous work reported on aged flavor in country style hams
has been mostly subjective in nature. A reliable objective test for
aged flavor development in this type of ham during storage would be
particularly useful in evaluating the influence of the kinds and
amounts of curing agents, and the effect of temperature, humidity
and airflow. Several papers have been published on the chemical
and physical factors involved in the curing and aging; the most
extensive of these is by Hunt, Supplee, Meade and Carmichael
(1939). However, this work is concerned primarily with the chemi-
cal changes and secondarily in any association of such changes with
aged flavor taste. More recently, Weir and Dunker (1953) com-
pared certain chemical constituents of ham with organoleptic tests.
This work was done with four different types of commercially cured
hams so applies only indirectly with country style hams.

Country style hams are cured by essentially two methods.
The first is the dry-cure, where salt, sugar and sodium or potas-
sium nitrate are applied directly to the surface area of the ham.
The second method is the brine-cure method which consists of use
of the same ingredients except that they are added to water and the
hams immersed in the brine. A survey of 1300 farmers by Dunker

and Hankins (1951) has shown most farm meats are cured by the

2
dry-cure method. This survey also revealed that the curing agents
used were: salt only; a home mixture containing various combina-
tions of salt, sugar and pepper and saltpeter; and a commercially
prepared mixture. The figures further showed that 80 per cent of
the farmers dry-cure and 20 per cent brine-cure their meat; only
9 per cent pump their meat prior to curing. In addition to farmers,
locker plant Operators and meat packers in certain localities use
the dry-cure method.

This investigation is concerned chiefly with the quantities of
certain chemical components deve10ped during the curing and
storage of dry-cure country style hams. It is limited to the analy-
sis of the water soluble non-protein compounds. Further, a com-
parison is made between the quantities of these chemical compo-
nents at three different storage periods with taste panel ratings for
aged flavor, tenderness and saltiness. Finally, the most reliable
of these chemical measurements are used to formulate an equation

that attempts to predict the degree of aged flavor in ham.

   

HISTORICAL REVIEW

This review is based on the literature dealing with the
function and effect of curing ingredients used to cure country style

hams and the evaluation of food flavors.

Function and Effect of Curing Ingredients

The curing agents listed as permissible in the regulations by
the Bureau of Animal Industry (1925) other than spices are: salt,
sugar, sodium nitrate, sodium nitrite and vinegar. Salt is the most
important preservative ingredient used (Jones, 1937; Moulton and
Lewis, 1940; Jacobs, 1944; Jensen, 1945; and Ziegler, 1948). Its
chief function is to help prevent the growth of undesirable bacteria
which commonly have access to meat.

According to Callow (1947) the process by which salt is
absorbed in fatty tissue by way of its connective tissue is quite sim-
ple. In contrast, the principle of salt absorption in muscle tissue
is rather complex. Immediately after death of an animfl, the
muscle fibers are filled with fluid, but very little fluid is between
them at this time. This condition of the microstructure of muscle
is termed by Callow (1937) as a "close" one. In this state, salt
absorption is comparatively slow. Later, the muscle glycogen in
the fibers is converted to lactic acid causing them to shrink and

give off fluid. He refers to this condition as an "Open" structure.

Both salt and sugar may penetrate into muscle with an Open
structure more rapidly than into that with a close structure.

Callow (1936) stated that the change from close to an Open structure
is accomplished most completely at pH 5. 7. In addition to hasten-
ing the penetration of salt, a low pH inhibits the growth of
anaerobic bacteria. Ingram (1939) found that about 5 per cent salt
can prevent the growth of anaerobic bacteria even when no acid is
present.

Salt diffuses into the muscle tissue and water diffuses out
during the curing process. This progresses at a slow rate with the
dry-cure. In one respect, this slow rate of diffusion is advantageous
if the theory of Callow (1947) is applied. A salt-protein complex is
eventually formed where the osmotic pressure Of the complex is
greater than the surrounding solution. In brine-cure hams, this
point may be reached comparatively soon; the water then flows back
into the muscle fibers, and thus Offers an explanation for the gain
in weight Of cured meat over fresh meat. In dry-cure hams, the
removal Of water and entrance Of salt in muscle tissue continues for
a much. longer period making conditions less favorable for bacterial
growth as the curing period progresses.

A disadvantage of dry-cure for hams is the length of time
necessary for the absorbed salt to become equalized throughout the

muscular tissue. In a study of the movement of salt after curing,

5
Miller and Ziegler (1936) and Ziegler and Miller (1938) showed that
the outside inch of ham is at least ten times as great as in the
center at the time they are removed from cure. According to
Miller and Ziegler (1936), (1939); Besley and Hiner (1937) and
Ziegler and Miller (1938), the length of time necessary for salt
equalization intheham is dependent upon the weight and thickness.
The moisture-salt content and the amount and distribution of fat
have been found by Blumer, Smith, Lucas and Tyler (1952) to be
important factors in the rate Of salt distribution. An increase in
salt content will decrease the time necessary for any point in the
ham to reach a "safe" salt concentration. A safe salt concentration
with respect to spoilage was given by the Bureau Of Animal Industry
(1941) as 5 per cent. A high moisture content will allow a com-
paratively rapid distribution of salt. A high moisture content is
usually associated with a low fat content in fresh hams; therefore,
fat retards the distribution of curing ingredients.

From a flavor standpoint it is Obvious that salt in an impor-
tant flavor component in cured hams.

Sugar is ordinarily added to the curing mixture used for
country style hams as cane or beet sugar in a crystalline form. It
is added primarily to aid in the develOpment Of proper color as
shown by Haldane (1901); Jensen (1935); Lewis (1936); Brooks (1937),

and Greenwood, Lewis, Urbain, and Jensen (1940). It is also,

according to Lewis (1937), added for the purpose of reducing the
hardening effect caused by the action of salt: Several workers,
Tomhave (1925); Helser (1929); Moulton (1929); Warner (1938) and
Ziegler and Miller (1938), have noted that a more desirable flavor
develops when sugar is added to the curing mixture. It is possible
that this difference may be due to texture. Lewis (1937) stated that
sugar does not Mpart a sweet flavor to cured ham. Further evi-
dence that sugar may not be a detectable flavor component was
noted by Brady, Smith, Tucker and‘Blumer (1949). These Observa-
tions do not preclude the possibility that sugars, when added, are
included in the final flavor result but are masked by the presence of
stronger flavor components.

It should be mentioned that, like salt, sugar functions as a
preservative. This is probably accomplished in curing hams by
acting as a dehydrating agent. A protein containing food loses water
to a sugar solution, but Callow (1932) reported that a sugar-complex
is not formed as is the case with salt. Therefore, liquid will be
removed and cannot be replaced. Probably the liquid is held be-
tween the muscle fibers and may account for the softer texture as
compared to no added sugar.

The stable red color characteristic of cured meats is enhanc-
ed through the addition of nitrate or nitrite. The origin for this

custom is unknown. The most probable explanation is that it was

an impurity in the salt used in early times. Its continued use is
mostly for aesthetic reasons; however, any deviation from the
normal color is considered to be a product of inferior quality.
There is some evidence that nitrite has some preservative action,
but this will be presented later.

A number of papers has been published on color and color
formation. Reference is made here only to those having a relation-
ship tO this study and to those which add to the clarity of explaining
the function Of nitrates and nitrites.

A graphic presentation of the chemical compounds involved
was given by Greenwood, Lewis, Urbain and Jensen (1940) beginning

with the fresh meat and continuing through the cooking Operation.

 

(1) Hemoglobin Oxyhemoglobin (1)
Hb (purple) 92 .. Hb 02 (red)
Ferro-Compound 4 FerrO-Compound

 

  

(l) Nitric oxide hemoglobin Methemoglobin (2)

 

NO Hb (red) . MHb (brown)
Ferro-Compound Perri-compound
denaturation excess nitrite, oxygen
(heat and time) and microorganisms
(l) Nitric oxide hemochromogen Other oxidation pigments
(red) (green, grey, brown)
Ferro-compound (2) Ferri-compounds

(l) = Desirable pigments (2) = Undesirable pigments

8

Sugars were mentioned previously as being beneficial to color
formation. They help by assisting in the maintenance of conditions
favorable for the growth Of microorganisms that ferment sugar to
acid. The reducing conditions thus established are essential for
proper color formation. An excessive number of microorganisms
_ if present in combination with appreciable quantities of reducing
sugar will produce undesirable pigments. This principle of pH is
essentially confirmed by Duisberg and Miller (1943), Urbain and
Jensen (1940); Urbain and Greenwood (1940); White and Gibbons
(1.941); and Gibbons and Rose (1950). Nitrite destruction is caused
due to the instability Of nitrous acid which is formed in acid solution.
These workers showed that prOper color fixation is best accom—
plished between a pH range of 5 to 6. In cases where the pH is high
and the temperature low, the rate Of oxidation is slow. Brooks
(1929), (1936) stated that the complete absence of Oxygen tension
within the meat permits the use of nitric oxide hemoglobin as a
meat pigment.

Urbain and Jensen (1940) claimed that the pigments of cured
meats are nitric oxide myo-hemoglobin and nitric oxide myo-
hemochromogen. The chemical prOperties, however, were not
unlike those reported by other workers. They noted that at 10° C
(50° F. ), a pH Of 8. 25 appreciably retarded the oxidation Of nitric

oxide hemoglobin; lower pH's increased the rate of oxidation. This

9
instability of nitrite makes it necessary to include nitrate in curing
mixtures. Kleckner (1942) stated that this is true even though its
production from nitrate depends upon many factors not easily
standardized. Rose and Peterson (1953) described the limiting
factor in the rate of nitrite reduction as an intermediary electron
carrier rather than the overall reducing system.

Nitrite has been shown to have some preservative action.
According to Tarr (1941), it is most effective in an acid medium.
Therefore, the full benefit should be realized in cured ham. In
comminuted pork seeded with spores of a Clostridium species,
Bulman and Ayres (19 52) found that nitrate had about the same pre-
servative effect as sodium chloride, but nitrite had a preservative
effect at levels as low as 0. 04 to 0. 08 per cent. In uninoculated
meat these workers found that nitrite used in combination with
sodium chloride or nitrate appeared to extend the storage life of
pork.

It should be recognized that certain chemicals are added to
cured meats during the smoking process. These are listed in the
papers of Rideal (1903); Callow (1927); Hess (1928) and Pettet and
Lane (1940). The most abundant of these are formaldehyde and
higher aldehydes; formic, acetic and higher acids; phenols, ketones

and resins. These chemicals also have a preservative action in

10
their prOperty to stabilize fats as shown by Lea (1933); White,
Gibbons, Woodcock and Cook (1942), and White (1944).

Smoke also has some preservative effect through its action on
bacteria as shown by White, Gibbons, Woodcock and Cook (1942)
and Jensen (1943). Jensen found low nitrite, good color and few
bacteria at the end of an 18 hour smoking period. He also associ-
ated smoking with the production Of desirable organoleptic properties.
Flavor of woodsmoke is not discernible, however, from the overall

flavor in aged country style hams.

The Evaluation of Food Flavor

Any food is evaluated by its conformity to a certain standard
of perfection. Raw meat is evaluated by its appearance. This
includes the prOportion Of fat, lean and bone, the color Of fat, lean
and bone, its texture and the intramuscular fat, commonly called
marbling. The cooked meat is also evaluated by its conformity to
an appearance standard, but in addition, to its conformity to a
flavor standard. Since flavor ideals vary widely with different
peOple, methods of accurately estimating and comparing flavor have
presented a problem.

Most Of the flavor tests conducted have been Of a subjective
nature; that is, they are based on the Opinions of peOple. More

recently, Objective measurements have been used in an attempt to

ll
evaluate food flavors. These are based on chemical, physical and
microbiological prOperties. In the review of literature that follows

the subjective method of food evaluation will first be considered.

Subjective Evaluation of Food

There are only four basic tastes; these are sweet, sour,
salty and bitter (Fabian, 1940; Crocker, 1945; Remer, 1947;
Maximow and Bloom, 1948). Taste is discerned chiefly by the taste
buds. Maximow and Bloom stated that taste buds are found on the
surface of the tongue, glassOpalatine arch, soft palate, posterior
surface of the epiglottis, and on the posterior wall of the pharnyx
down to the level of the inferior edge Of the cricord cartilage.
Taste buds are shaped like a flask with a wide bottom and a short
neck. Under low power of the microscOpe, they are seen in sec-
tions as pale, oval bodies in the darker stained epithelium. They
are about 72 microns in length. They are in an upright position in
the epithelial layer and extend through most Of its entire thickness,
from the basement membrane to the surface. A superficial layer
Of squamous epithelial cells over each taste bud is pierced by a
small Opening, termed the outer taste pore.

Two types of cells may usually be distinguished in a taste bud,
the supporting cells and the neuroepithelial taste cells. The taste

cells are distributed inside the bud, between the supporting cells.

 

 

12
They number from four to twenty in each taste bud. These authors
have noted that the four fundamental flavors listed above give a
varied reaponse as to their taste when they are applied to individual
fungiform papillae. Some of the papillae do not give any taste
sensations while others give sensations of one or more taste qauli-
ties. This is not due to structural differences in the various taste
buds, as they appear entirely similar. Also, a general chemical
sensitivity may be detected in regions of the mouth where there are
no taste buds present.

The saliva secreted by the various salivary glands has a role
in food flavor or, at least, acceptability. It contains water, mucin,
proteins, mineral salts, and the enzyme ptyalin, which Splits
starch intowater-soluble, less complex carbohydrates. The secre-
tion Of the glands is affected by the different kinds of food eaten,
depending upon the nature of their stimuli.

Subjective tests used to evaluate food flavor may be divided
into two main categories depending upon their purpose. Lowe and
Stewart (1947), and Langwill (1949) classified them as preference
or acceptance tests and difference or psychometric tests. In pre-
ference testing the degree of acceptance is obtained. The purpose
Of the difference tests is to determine quantitative differences by
rating or scoring Of food quality factors. Platt (1937) suggested

that the difference test should be used where the standard of

13
perfection has been agreed upon; the preference test to determine
how well the general public will like a given food.

Flavor difference tests. One Of the most widely used systems

 

for judging meat flavors has been used by Black, Semple and Lush
(1934); Barbella, Hankins and Alexander (1936); Brady (1937);
Griswold and Wharton (1941); Hardy and Noble (1945) and Noble and
Hardy (1945). The COOperative Meat Investigations Board adOpted
this chart for scoring meat flavors. It is a numerically graded
charthaving numbers from one to seven and increasing in intensity
directly with the size of the number. A descriptive adjective
accompanies each number and factor considered.

Other scoring systems have been used such as the zero to ten
by Steinberg, Winter and Hustrulia (1949), and the two to fourteen
system of scoring used by Ramsbottom, Strandine and Koonz (1945)
for rating the tenderness of beef muscles. This is comparable to
the one to seven system described above since an increase in
tenderness is designated in units of two.

Selection of taste panel. The selection of a taste panel for

 

evaluating difference in food is based initially on availability of
personnel as emphasized by Black, Semple, and Lush (1934); Carl,
Watts and Morgan (1944); White, Woodcock and Gibbons (1944);
Fenton (1946); and Lowe, and Stewart (1947). Secondly, the mem-

bers of the panel are selected on their ability to detect and evaluate

l4
taste differences. It is best to use a trained or experienced panel
as indicated by Alexander, Clark and Howe (1933).

If a trained panel is not available, the size of the panel
desired is decided upon. There is quite a difference of Opinion in
the literature as to the number necessary. Although there are
some extremes, the number usually used is between three and ten
peOple. Platt (1931) was of the Opinion that five to ten judges may
be used depending upon the number of qualified judges available. If
panel members selected are approximately equal in proficiency,
Marcuse (1947) stated that a larger panel will permit more con-
fidence in the average score. Peret (1949) stated that a panel of
competent tasters is more reliable than a larger group, some of
whom would probably be incompetent in their evaluation.

Sex appears to have no bearing on tasting ability. Snyder
(1931) has indicated that taste deficiency is not sex-linked nor sex
influenced. Taste deficiency is primarily due to a single recessive
gene. Studies may be found in the literature which support the use
of either male or female panels but it seems highly probable that
no significant difference exists.

To select panel members from a group of people inexperi-
enced in tasting a food, one of several means may be used. The
two methods most frequently used with recent work are the triangu-

lar and two-sample taste -test methods. Advocates of the triangle

15
taste-tests such as, Roessler, Warren and Guymon (1948); Hening
(1949); and Girardot, Peryam and Shapiro (1952) stated they are
useful for selecting personnel for expert panels, wherein individual
sensitivities to different taste factors are evaluated. In this test,
three samples are tasted, two Of which are alike. The judges are
asked to select the Odd sample. This test is also suggested by
Roessler, Warren and Guymon (1948) for use with expert panels to
note if differences are detectable between two different food
samples. If a difference exists they may then be used to evaluate
an inexperienced panel or a" group Of peOple to determine food pre-
ference trends. The results of this method of testing may be
analyzed statistically.

The paired test method has been used by Cover (1936), (1937),
(1940), (1941), (1943); Griswold and Wharton (1941) and Boggs and
Hanson (1949). As the name implies, two samples are submitted
to the judges. In testing with this method it is essential that a
similar set of samples be scored at least two and preferably more
times to avoid chance selection. If the second set is evaluated
similarly by the judge it may not be necessary to repeat the test.
One of the chief objectiOns to this method of testing is the time
necessary to evaluate a group Of samples. Also, since the tests

must be repeated, much labor is involved. Its use is somewhat

 

 

l6
liJnited, but in cases where only two variables are present it is a
convenient method. It worked quite well in this reSpect in the work
Of Cover (1937).

Byer and Abrams (1953) compared triangle and two sample
taste methods using different concentrations of aqueous solutions
of quinine and dextrose. The two—sample test showed results
favoring this test over the triangular test in discriminatory value.
The same was found true for quality judgments made within these
experimental tests.

Another method of selecting judges is by use of the ranking
test. In this test the judges rank the food with respect to the con-
centration of a certain flavor component, such as saltiness or
sweetness. Ranking tests have been used by Crist and Seaton (1941);
Carl, Watts and Morgan (1944); White, Woodcock and Gibbons
(1944); Averman and Li (1948) and Crocker, Sjostrom and Tallman
(1948). This method may be used most conveniently when only one
or two flavor components are to be evaluated. Obviously the factor
must be of a' nature that will permit varying intensities to be pre-
pared for tasting. Also, a suitable standard material must be
available.

The dilution test may be used for some foods, but does not
apply too well to meats with the exception of ground meats. It is

only desirable for use with food that may be made homogeneous.

17
Dilution and ranking tests may be used in unison. The most frequent
use of dilution tests has been made in evaluating individuals for pri-
mary tastes as done by Crocker (1937); King (1937); Knowles and
Johnson (1941) and Fabian and Blum (1943).

Training the taste panel. Unless an experienced taste panel

 

is available, the members of the panel must be trained. The ability
to distinguish definite tastes can be improved with practice. This
may require only one week or up to several weeks, according to
Harding (1948), depending upon the sensitivity required and the
number of factors involved. The judges' scores during the training
period are noted for accuracy. If any judge deviates frequently
from the mean, ’Hening (1949) claimed the judge should be replaced.
This author gave a statistical formula suitable for testing signifi-
cance of the differences in judges' scores. Deviation in judges'
scores from the mean score of the panel has been used for checking
the dependability of individual tasters by Peret (1949) and Terry,
Bradley and Davis (1952). Harding (1948) stated that the taste test-
ing should be held under conditions which are comfortable for the
panel members. A well-lighted, preferably air-conditioned room
is most suitable. If possible each panel member should work in a
separate taste booth, where he may not Observe the other panel

members .

18
It is not advisable to judge foods in the same laboratory
where the food is cooked (Cover, 1936; Dove, 1947; and Moser,
Jaeger, Cowan and Dutton, 1947). Other conditions such as time
allowed for tasting, water for mouth rinsing to remove "carry over"
flavors, and the temperature of the samples are important. These

must be regulated to a standard procedure.

Comparison of Objective and Subjective Flavor Scores

Lowe and Stewart (1947) noted that the reliability Of any
chemical or physical measurement used in the determination Of
flavor must be evaluated in terms of its agreement with subjective
flavor scores. The authors stated that it is desirable to employ
both subjective and objective tests in connection with research on
the functional and organoleptic pr Operties of food products. When
a good Objective test is established simultaneous organoleptic tests
will sometimes prove helpful in explaining unexpected results for
either test.

There has been some reported success in correlating tender-
ness in meat with taste panel scores and the mechanical shear test
method as shown by Brady (1937); Griswold and Wharton (1941);
Cover (1943) and Paul, Lowe and McClurg (1944). The Warner-
Bratzler shear apparatus, reported by Bratzler (1932), measured

the shear strengths fairly satisfactorily for duplicate samples in a

 

 

19
study by Deatherage and Reirnan (1946) and Deatherage and Garnatz
(1952), but they did not correlate too well with taste panel scores.

No significant decreases in palatability scores were noted by
Steinberg, Winter and Hustrulid (1949) for stored beef with a 5 per
cent moisture loss.

Ether-extract of the fat determinations in the lean of steer
beef was shown by Branaman, Hankins and Alexander (1936) tO be
directly related to preference ratings by the judges.

Peroxide values of pork fat did not give good correlations with
taste panel scores in studies by White, Woodcock and Gibbons
(1944); Pearce (1945); Nauman, Brady, Palmer and Tucker (1951)
and Hanley, Everson, Ashworth and Morse (1953). Schreiber,
Vail, Conrad and Payne (1947) noted that the loss of flavor in frozen
poultry paralleled increases in the peroxide determination value of
the fat. The same trend was noted by Gortner, Fenton, Volz and
Gleim (1948) with pork in frozen storage at comparatively high
temperatures.

Press fluid determinations by Satorius and Child (1938)
showed no direct correlation with flavor or aroma scores of a taste
panel. However, Hardy and Noble (1945) found juiciness scores
and taste panel scores were highly significant in roast pork loins.

This is not a reliable test since the authors stated that the

20
difference is not great enough to predict judges' scores from the
juciness scores.

In cured, smoked meats White, Woodcock and Gibbons (1944)
found no correlation between aging period and flavor quality.

Cracker (1945) was of the Opinion that volatile organic acids
account for part of the flavor in fresh meat and that nitrogen com-
pounds are contributing factors. Crocker (1948) stated that the
flavor in raw meat is mostly in the juice and appears to be due to
certain aspects of the blood. To some minor extent meat flavor
may be due to the presence of creatinine and creatine. This author
stated that there is a sweetness of taste in pork flesh which is more
pronounced than in beef, a high volatile fatty acid content and
additional bases among which are an earthy-potatoey flavor and a
sulfury flavor somewhat similar to chicken. Red-meats were said
to give flavor characteristics that were similar to fish and birds,
while fish contained red meat characteristics.

Crocker (1935) reported that by searing a pot roast in hot fat
at high temperature, a change in flavor is produced. Meat sugars
are carmelized and nitrogenous bodies are said to undergo a partial
carbonization.

Bouthilet (1951) in a series of studies on the volatile constitu-
ents of chicken concluded that the "meaty flavor" in chicken is due

\

to a compound located in the meat fibers rather than in the fat.

21
Glutathione was the compound reported as having prOperties most
similar to the flavor compound.

Chemical changes in cured meats. It has been indicated that

 

meat may undergo many changes during the curing process due to
its complex composition and that these changes influence the flavor.
A National Livestock and Meat Board publication (1940) lists the
major food constituents of meats as proteins, fats, inorganic con-
stituents (minerals), carbohydrates, nitrogenous and non-
nitrogenous extractives, pigments, enzymes, vitamins and water.
Cured hams aged at atmospheric temperatures by Hunt,
Supplee, Meade and Carmichael (1939) showed changes in chemical
composition. The following conditions were Observed: Fat hydroly-
sis during the early months of aging was more rapid in the fat of the
lean meat than in the fat Of the adipose tissue; the amount of mois-
ture present influenced the rate of fat hydrolysis; total nitrogen in
the lean meat on a moisture and fat-free basis increased from
approximately 2. 3 per cent in the freshly cured hams to 3. 5 per
cent after aging one year; the sodium chloride concentration increas-
ed from approximately 6 per cent in dry-cured hams after aging one
month to 8 to 10 per cent after aging one to two years; unsaturated
acids were freed to a much greater extent than saturated acids
during the early stages Of aging; the iodine number of the free fatty

acids decreased as hydrolysis continued. The authors stated that

22
the difference observed in the rates of hydrolysis of unsaturated
and saturated acids is probably characteristic of enzymatic hydroly-
sis of fat under all conditions.

In cured and smoked meats the bacterial count, peroxide
oxygen content of the fat and color of the lean changed directly with
the length of the aging period as found by White, Woodcock and

Gibbons (1944).

EXPERIMENTAL PR OCEDUR E

The hams used in this study were obtained from hogs of
similar breeding, fed the same feed and grown under similar
methods Of management. The hogs were slaughtered when they
reached a live weight of 200 to 240 pounds. They were not fed for
a 24 hour period prior to slaughter, but had free access to water.
After slaughter the carcasses were chilled for 48 hours at 0. 56° to
1. 67° c (33° to 35° F. ), at which time they were fabricated into
wholesale cuts. The hams were cut regular style and weighed from
13 to 16 pounds. A period Of about six months was required to
collect the 54 hams used in this study.

The hams were cured by the dry-cure method. The curing
mixture was composed of eight pounds of kiln dried granulated
sodium chloride, two pounds of table grade, white cane sugar and
two ounces of sodium nitrate. The salt contained the following
impurities: calcium sulphate 0. 28 per cent, calcium chloride 0. 03
per cent, and magnesium chloride 0. 01 per cent. The curing mix-
ture was applied to the hams at the rate of one ounce per pound Of
meat. The proper amount of curing mixture was weighed for each
individual ham and divided into three equal parts. These parts were

rubbed on the hams on the first, fourth and tenth days. During the

II

 

 

 

24

curing period the hams were held at a temperature of 4. 44° C
(40° F.) '3: 1°. They remained in cure two days for each pound of
ham.

At the end of the curing period, in order to remove the sur-
face salt, the ham's were removed from the curing room and im-
mersed for two [hours 'in a bath of cold water. A constant incoming
supply of water kept the water bath fresh the entire time. The hams
were then removed and hung to dry in a gas heated smokehouse in
which the temperature was held at approximately 32° C (90° F. )
with the aid of a thermostat. After two hours drying time smoke
was generated by burning a hardwood sawdust. The smokehouse
temperature during smoking was maintained at the sametempera-
ture as for drying. A continuous 24 hour smoking period was used
for each group of hams. They were then stored at approximately
4. 44° C (400 F.) at an average relative humidity of 45 per cent
until they were sampled. While it is acknowledged that country
style hams are usually stored at atmospheric temperatures, the
lower temperature was used to keep the growth of surface micro-
organisms at a minimum. Even though the aging process proceeds
at a slower rate at this temperature, the advantage in reducing

environmental variations was considered to be Of major importance.

x

I :

 

 

 

 

25
Sampling Methods for Hams

The stored hams were sampled at the end Of the first, sixth,
and twelfth months. The identity of each ham was maintained
throughout the duration Of this study by tagging it with the number
corresponding to the hog from which it was removed. When a group
of hams was first placed in storage, one ham from each pair was
randomly assigned to the group to be analyzed at the end Of the first
month. These hams composed the control group. When a ham was
drawn for the control group, the other member Of the pair was
assigned to the sixth month group for the first half of the numbers
drawn; the remaining hams were then placed in the twelfth month
group. The use of this procedure, therefore, allotted twenty-seven,
thirteen and fourteen hams to the first, sixth and twelfth month
sampling periods, respectively.

The ham samples were obtained by removing three adjacent
ham slices one -half inch in thickness, beginning at a point one quar-
ter inch from the posterior end Of the ischiurn. The first and third
slices were used to determine the degree Of aged flavor, tenderness
and saltiness by means of a taste panel. The second slice was used

for chemical analyses.

Selection of the Taste Panel

The taste panel was selected from a group of 71 persons. For

convenience in evaluating the most proficient tasters, this group

26
was divided into three smaller groups. As test material two pairs
of hams were Obtained; these two pairs were judged to have a detect-
able difference in aged flavor, tenderness and salt content. These
differences were not considered extremely great, so that some
degree of skill was necessary in order to receive a good score.

The hams were sliced in such a way that the pair mates when
tasted by the panel were from comparable ‘slices as to location in
the ham. Each group scored each pair of hams on two different
days. The triangle test method was used, but in addition to select-
ing the odd ham the tasters were asked to score each ham as follows:
Aged flavor - high or low; tenderness - high, medium or low; and
saltiness - high, medium or low. The same pair Of hams was
tasted and scored twice on any given day, however, a different ham
was used each time for the odd sample. Ten tasters, six men and
four women, made no more than one error in judgment on any
factor. These ten persons formed the panel used in this study.

Preparation of samples for taste testing. The first and third

 

slices from each ham were broiled in the oven of an electric range.

I The slices from all first month hams were placed seven inches
from the source of heat and broiled for 20 minutes at 176. 67° C
(350° F. ). The sixth and twelfth month hams browned more quickly;

therefore, they were broiled for only 15 minutes.

 

 

 

 

*—

m~

27
The cooked samples were trimmed free of fat and the semi-
membranous, abductor, semitendinosus and the biceps femoris
muscles were cut into approximately one-half inch cubes. The cut
samples were thoroughly mixed and served on plates to the mem-
bers Of the panel.

Tasting and scoring samples. The plates were identified by

 

a number assigned to correspond with the ham number. Since no
individual tasting booths were available, the test was conducted in
a classroom where plenty of space could separate the individual
tasters. A minimum of six tasters was used for any taste test and
a maximum of eight.

Each panel member chose at random one sample of meat
from each plate. Three factors, namely, aged flavor, tenderness
and saltiness were scored on a sheet provided with three geometri-
cal figures Of similar design. Each figure was constructed in such
a manner that ten equally spaced lines originating from a common
straight line base traversed in an 180 degree semi-circle. Each
figure was designated, "flavor", ”tenderness" or ”saltiness". The
fir st, fifth, and tenth lines of each figure were heavier than the
lines in between. These heavy lines were labeled: threshold,
appeal and excess. This is a modification of the system used by
Cartwright and Kelley (1951) and called a profile test. The word

threshold, labeled as such on line one, was used to represent the

28
lowest possible score for any one factor. The word appeal, appear-
ing on line five, was the most ideal rating for any one factor.
Excess, was the designation given to line ten. The interpretation
Of the interspaced lines using the heavy lines as reference points
was as follows: the lines between one and five were the divisions
dividing the threshold interpretation from the ideal interpretation
for any single factor. That is, any line below five was less than
the prOper amount. Similarly, any line above five was understood
to be more than the desired amount. This scoring system was used
for all hams tasted and for all three factors evaluated.

The panel had the Opportunity to use the modified Cartwright
and Kelly system Of scoring on five different occasions prior to
beginning this study. An effort was made to train the panel at these
times by using hams considered to have "appeal" ratings for any or
all of the factors to be tasted and comparing them with hams having
more or less than an appeal amount. A sample score sheet is shown
in Fig. 1. It may be Observed that all hams for any one test period
were recorded on the same sheet. This gave a graphic representa-

tion of all hams tasted at any time during a tasting period.

Preparation Of Samples for Chemical Analyses
The four muscles used in the taste test were also removed

from the second slice for the chemical determinations. The outer

Name 29

 

Date

 

 

 

 

 

 

”Old

 

 

 

SALTINE SS

Fig. 1. Sample Score Sheet - Taste Test Evaluation
(12 Months)

30
fat was removed from the ham slice and used for determining the
iodine number of the fat. The lean tissue was finely chopped with a
knife and thoroughly mixed. Twenty-five grams of this tissue were
weighed on a balance and diluted with 250 ml of distilled water.
This mixture was then ground in a Waring Blendor for five minutes
and filtered through fine filter paper and a Buchner funnel by
mechanical suction.

The water extract was clarified by treating it with a l N solu-
tion of zinc sulphate at the proportion of ten to one. This mixture
was then poured into a 250 ml capacity beaker and placed on a mag-
netic stirrer. The glass electrodes Of a Beckman pH meter were
then adjusted into the solution. A 1 N solution of sodium hydroxide
was then added with continuous stirring until a pH of 7. 8 had been
reached. The neutralized mixture was poured into 50 ml glass
centrifuge tubes and centrifuged for 15 minutes at 3000 revolutions
per minute. The clarified liquid was then poured off and stored in
250 ml glass stOppered flasks in a refrigerator maintained at about
5° C. until used. The clarified solutions were used for the deter-
mination of the water - soluble compounds.

The remaining chopped muscle tissue was used as described

under the section on analytical procedures.

ANALYTICAL PR OCEDUR ES

Moisture. Five grams of the chOpped lean meat were dried
in an electric drying oven for 36 to 40 hours at 70° C. The meat
was then dried for five additional hours in a vacuum oven at the
same temperature, cooled in a desiccator and weighed.

£113. The crude fat was determined on the moisture free sam-
ple by the method described in the Association of Official Agricul-
tural Chemists (1945).

Salt. The salt content was determined by the electrometric

 

titration method as described by Brady, Smith, Tucker and Blumer
(1949).

£11. The pH was determined with a Beckman pH meter equip-
ped with a glass electrode apparatus.

Iodine absorption number. The Hanus method was used to

 

determine iodine numbers as given in the Association of Official
Agricultural Chemists (1950).

Free fatty acids. The free fatty acids were determined by a

 

slight modification Of the method described in the Association of
Official Agricultural Chemists (1950). Five grams of the ham fat
were used in place of 7. 05 grams. The sodium hydroxide for
titration was standardized between 0. 10 N to 0. 20 N instead of

exactly 0. 25 N.

 

 

32

Total nitrogen. The Kjeldahl - Gunning - Arnold method was

 

used as described in the Association Of Official Agricultural
Chemists (1945) with one exception: the sample was collected in
50 ml of boric acid according to the method of Scales and Harrison
(1920).

Soluble nitrogen. The sample was prepared for the deter-

 

mination of soluble nitrogen by blending ten grams of the ham sam-
ple and 100 ml of water in the Waring Blendor for five minutes.
The mixture was filtered by suction through sintered glass crucibles
containing a small amount Of Hyflow Supercell. Some supercell was
also added to the solution before filtering. A 10 ml aliquot of the
filtrate was ”then determined according to the Kjeldahl method
described above.

Glucose. Five ml of the water extract were analyzed for
glucose according to the method of the Association of Official Agri-
cultural Chemists (1950).

Peroxide number. The method of Stansby (1941) was used to

 

determine the peroxide content of the hams.

Unsaturated fatty acids. Fifty grams of each ham were ground

 

with 75 m1 of alcohol in a Waring Blendor. The mixture was then
boiled for 15 minutes and the alcohol removed by filtration. The
ham tissue was re-extracted twice, using 75 ml Of boiling alcohol

each time; then the residue was washed with 100 m1 Of ether and

 

 

33
dried in a vacuum oven at 500 C. The alcohol and ether extracts
were combined and brought to dryness under reduced pressure in an
atmosphere of nitrogen. The remaining lipids were dissolved in
ether, dried with anhydrous sodium sulfate, and added to the previ-
ously dried ham tissue. This was extracted overnight, in a modi-
'fied Pickel extractor, by anhydrous ether. The levels Of the
unsaturated fatty acids were determined spectrOphotometrically
after alkali-isomerization according to the general procedure of
Mitchell, Kraybill, and Zschiel (1943) as modified by Brice, Swain,
Herb, Nichols and Reirnenschneider (1952).

Lactic acid. Lactic acid was determined by the method of

 

Barker and Summerson (1941) on 1-5000 dilutions of the protein
free extracts Of the hams. The lithium lactate used in making the
standard solutions was recrystallized from alcohol until duplicate
values were Obtained from two successive colorimetric readings.

Glycerol. The glycerol was determined according to the
method of Lambert and Neish (1950).

Short chain fattyacids. Ten ml Of the water extract was dis-

 

tilled by continuous ether extraction and prepared for chromato-
graphic separation according tO the method of Neish (1950). The
separation technique of Marvel and Rands (1950) was used for

separating the individual acids with the following exceptions: the

solvent material was forced through the chromatogram tube with

34

nitrogen gas using a regulated pressure so that about 2 ml per
minute were collected in 10 ml fractions in graduated cylinders;
carbon dioxide free water in the quantity of 2 to 1 was added to the
collected fractions before titration, and a stream of carbon dioxide
free air was introduced into the titration flasks during the titration
process.

Organic matter. The organic matter was determined on the

 

clarified ham extract by the method Of Johnson (1949).

R ESULTS

The taste test scores and analytical values were analyzed by
calculating the differences between paired hams in storage one
month with those in storage six and twelve months. The difference
between six months and twelve months was then determined. A test
of significance was performed on each group difference (Snedecor,
1946) (See Tables IX and X).

Taste Tests
(See Table 1)

Flavor. Inspection of the data shows that aged flavor
increases progressively with time. The greatest increase was
between six and twelve months. A significant increase in taste test
scores is shown at twelve months (See Table IX). Flavor and taste
test saltiness and chemical salt values are significantly correlated.

Tenderness. A slight increase trend in tenderness was found

 

at six months; a somewhat smaller decrease for twelve months. '
The differences were not significant.

Saltiness. The taste test scores indicate that salt concentra-
tion increased progressively with time. A marked increase was
recorded for both six and twelve months. The largest increase was

between these sampling periods.

 

 

 

TASTE PANEL SCORES

TABLE I

l

36

 

 

Ham Code Ham Code

No'. NO 1 MO. 6 M0. _No. No. 1 MO. 12 MO.

Flavor

53 1 2. 88 3.17 228 1 5. 12 4. 00
250x 2 3.38 3.00 551 2 3.71 3.62
462 3 3. 86 3. 83 556 3 4. 00 5. 00
552 4 3.86 4.28 590 4 3.43 4.75
570 5 2. 86 3. 71 606 5 3. 86 4. 00 l
572 6 3. 14 1. 86 656 6 3. 43 4. 50.
588 7 4. 00 3. 83 681 7 3. 71 4. 62
705 8 4. l4 4. 00 682 8 4. 57 4. 75
721 9 3. 57 3. 28 696 9 3. 28 4. 25
731 10 4.00 4.00 781 10 3.28 3.62
771 11 3.43 3.71 784 11 2.86 4.50
941 12 2. 43 3. 43 833 12 4. l4 4. 88
Average 3. 46 3. 51 3. 78 4. 37
Mean Difference +0. 05 +0. 59

Tenderness

53 l 3. 62 4. 00 228 l 4. 00 4. 00
250x 2 3. 88 4. 00 551 2 4. 28 3. 25
462 3 4. 43 4. 83 556 3 4. l4 3. 25
552 4 4. 43 4. 28 590 4 3. 71 4. 12
570 5 3 86 3. 28 606 5 4. 00 3. 12
572 6 4 00 4. 00 656 6 4. 57 4. 75
588 7 4. 57 4.33 681 7 3.71 3.75
705 8 4. 43 4. 57 682 8 4. 43 4. 12
721 9 4.43 5.14 696 9 4.43 4.38
731 10 4.14 4. 28 781 10 4.14 4. 00
771 ll 4. 28 3. 86 784 11 4. 28 4. 25
941 12 2. 71 4.14 833 12 2. 71 4. 38
Average 4 06 4. 22 4. 03 3. 95
Mean Difference +0. 16 -0. 08

 

 

37

TABLE I CONTINUED

 

 

Ham Code Ham Code

NO. NO. 1 MO. 6 MO. No. NO. 1 MO. 12 MO.

Saltiness

53 1 3. 25 3. 50 228 1 4.12 4. 62
ZSOX 2 4.25 3.33 551 2 3. 57 4.62
462 3 3. 57 3. 67 556 3 3. 57 6. 25
552 4 3. 57 4. 28 590 4 4. 28 5. 25
570 5 2. 86 4. 14 606 5 3. 28 3. 88
572 6 3. 00 3. 14 656 6 4.43 6.50
588 7 4. 28 5. 00 681 7 4. 28 7.14
705 8 3.71 4. 14 682 8 4.43 6. 12
721 9 3. 86 3. 86 696 9 3. 28 4. 75
731 10 4.14 4.28 781 10 4.00 4.71
771 11 3.28 3.86 784 11 2.86 4.62-
941 12 3. 86 4.14 833 12 3. 57 4. 57
Average 3. 64 3. 94 3. 81 5. 25
Mean Difference +0. 30 +1. 44

 

1 A l - 10 scoring system was used. A value of 5 is the best
possible score. Values below 5 represent an insufficient prOp-
erty and over 5 more than sufficient.

38
Chemical Tests

All values reported here were Obtained by calculating the
average of duplicate samples.

Moisture. The average per cent reduction in moisture for
the pairs at six months was 8. 56; at twelve months, 13.47. The
differences were significant at all sampling periods. They were
also significant between six and twelve months. Moisture and salti-
ness gave a negative correlation as expected. However, this differ-
ence was not large enough to be statistically significant. The same
is true between chemical salt values and moisture.

FEE. Variations in fat content between hams were larger than
might be expected with paired hams. The greatest variation was
found for the six months samples. Since the hams were paired it is
a safe assumption that this difference is due to sampling error.

Salt (fresh basis). An increase in salt concentration was

 

found for each successive sampling period. Per cent salt increase
was greatest between six and twelve months. This is in agreement
with the taste panel scores (See Table II).

Peroxide number. Higher peroxide values were obtained as

 

the length of storage period increased. In order to further Observe
the effect of peroxide value on flavor response, several fat samples
were obtained at weekly intervals from stored ham fats. The fat

thus Obtained was prepared for peroxide determination according to

TABLE II

39

MOISTURE, FAT AND SALT (FRESH BASIS) ANALYSIS

 

Per Cent Salt

 

 

 

 

Ham Code Per Cent Moisture Per Cent Fat (Fresh Basis)
NO. No. 1 MO. 6 Mo. 1 MO. 6M0. 1 Mo. 6 Mo.
53 l 64. 58 54. 14 6. 25 8. 00 4. 63 3. 81

250x 2 65. 78 57. 15 3. 26 6. 76 4. 3O 5. 00

462 3 64. 92 61. 46 6. 23 3. 46 5. 02 n 6. 82

552 4 66. 78 56. 40 4. 58 9. 34 4. 47 4. 19

570 5 64. 28 47. 59 5. 86 17.12 3. 83 4.18

572 6 63. 16 54. 26 ll. 36 13. 99 2. 59 3. 44

588 7 64. 88 59. 30 2. 70 4. 04 6. 14 7. 46

705 8 65. 84 45. 73 5. 34 18. 56 2. 68 5. 24

721 9 64. 39 56. 46 5. 29 5.15 3. 38 4. 91

731 10 65.44 61.41 4.42 7.70 4. 07 4.41

771 ll ' 68. 15 58.33 3.38 4.92 3.22 4. 18

941 12 56. 34 59. 18 ll. 44 9. 20 4. 53 5. 50

Average 64. 54 55. 95 5. 84 9. 02 4. 07 4. 93

Mean Difference - 8. 56 -+3. 18 +0. 86

12 Mo. 12 MO.

228 l 65. 00 48. 84 4. 59 7. 87 5. 29 6. 62

551 2 62.46 48.36 4.70 8. 58 3.71 4.81

556 3 64. 62 48. 58 3.17 7.14 3. 28 ‘ 7. 31

590 4 65. 48 49. 66 4. 30 6. 43 5. 52 9. 75

606 5 67. 67 51.86 4.78 7.39 2.81 4. 62

656 6 65. 44 46. 73 4. 30 7. 72 5. 60 9. 36

681 7 65.17 47. 93 4. 82 7.03 6. 00 9. 05

682 8 64. 42 50. 85 5. 01 7. 94' 5. 71 6. 05

696 9 58.42 46.95 10.72 9.73 3.81 9.97

781 10 51. 23 51.42 16.73 5.83 4.80 7.01

784 ll 64. 66 48. 98 6.10 6. 83 3. 40 4. 01

833 12 56. 45 49. 14 10. 69 6. 01 4. 12 5. 75

Average 62.58 49. ll 6. 66 7. 38 4. 50 7. 02

-13. 47 +0. 72 +2. 52

Mean Difference

 

40
the method previously cited. At the same time. small portions of
the melted fat were placed in the oven and heated for 10 minutes at
400 C, at which time they were removed and the Odor and taste
recorded by the taste panel. A change could be detected when the
peroxide value reached about 40. This change was due to a rancid
odor and flavor. Therefore, it may be concluded that the peroxide
value is not a good indication of aged flavor in hams. This would
apply in cases where the peroxide values are below 40‘; values in
this experiment were below 20.

Free fatty acid. Increases in free fatty acid content were

 

found. The greatest increase occurred between one month and six
months. Peroxide number, iodine number or glycerol content did
not appear to be correlated with free fatty acid.

Iodine number. A slight decrease in iodine number resulted

 

after six months; an increase after twelve months. Similar trends
were found for iodine numbers of outside fat and the fat extracted
from the muscle tissue (See Tables III and VII).

Chlor‘ides. The paired hams absorbed about the same amount

 

of salt when calculated on a moisture-free - fat-free basis. In a
few cases there were differences between pair mates, but by groups

there were no appreciable differences.

41

TABLE III

PEROXIDES, FREE FATTY ACIDS AND IODINE NUMBER ANALYSIS

 

 

 

 

Peroxides
Milliequivalents Per Cent

Ham Code Per kg Of Fat Free Fatty Acids Iodine Number
NO. No. 1 MO. 6 Mo. 1 MO. 6 MO. 1 Mo. 6 Mo.
53 l 2.17 1.58 1.08 3.49 66.90 66. 68
250x 2 2.77 5. 81 1.79 2.96 68. 10 57.20
462 3 7. 21 5. 94 1. 52 3. 24 68. 80 68. 06
552 4 4. 25 6.15 2. 37 4. 83 63. 76 64.18
570 5 4. 50 7. 21 2. 72 5. 58 62. 50 61. 90
572 6 3.92 11.96 2.45 5.36 62.32 62. 52
588 7 4. 28 12. 68 2. 07 4. 20 58. 96 60. 58
705 8 3. 84 10. 31 2. 87 4. 26 64. 62 62. 56
721 9 6. 62 5. 46 4. 01 5. 59 64. 29 63. 67
731 10 3.85 8.58 3.72 4.88 61.85 66.49
771 11 4. 61 14. 74 2. 20 5. 32 64. 95 66. 35
941 - 12 6.56 16.38 3.56 4.86 61.47 63.42
Average 4. 55 8. 90 2. 53 4. 55 64. 04 63. 63
Mean Difference +4. 35 +2. 02 - 0. 41
12 MO. 12 Mo. 12 Mo.
228 1 6. 20 6. 23 1. 96 3. 40 65. 69 73. 44
551 2 5. 60 5. 03 2. 04 5. 25 61.18 62. 32
556 3 6. 31 12. 84 2. 03 6. 25 63. 76 64. 74
590 4 7.71 7.81 2.22 5.76 61. 51 64. 19
606 5 5.15 7.28 2.81 7.72 63.01 63. 69
656 6 6. 74 6. 89 2. 08 5. 41 60.12 61. 33
681 7 5. 19 10.90 2.24 5.48 61.01 62.77
682 8 5. 64 8. 01 2.12 8. 38 63. 40 70. 64
696 9 3.77 10.26 2.76 5. 51 68.48 66. 39
781 10 5.64 8.05 2.71 5.80 65.12 67.71
784 11 6. 40 8. 97 2. 33 8. 97 62. 84 64. 78
833 12 4.62 6.40 3.38 6.95 63. 38 66.24
Average 4. 75 8. 22 2. 39 6. 24 63. 29 65. 69
Mean Difference +3. 47 +3. 85 + 2. 40

 

42

Soluble nitrogen. The greatest increase in soluble nitrogen

 

occurred between six and twelve months. A significant increase
was found for all sampling periods. This is in agreement with the
work of Hunt, Supplee, Meade and Carmichael (1939).

Total nitrogen. The total nitrogen increased with length of

 

storage period as was the case with soluble nitrogen (See Table IV).
£11. A very slight downward shift in pH was indicated.

These differences were not appreciable, so essentially the pH

remained the same.

Lactic acid. Although the lactic acid content tended to

 

increase with time at six months, the average value for twelve
months was slightly lower. These differences were not significant
for the paired hams.

Glucose. The glucose content remained nearly the same for
all sampling periods (See Table V).

Glycerol. The glycerol content showed very large increases
after storage at six and twelve months. These values were appre-
ciably different between sampling periods.

Organic matter. Values for organic matter markedly increas-

 

ed with time throughout the experiment (See Table VI).

 

Unsaturated fatty acids. Iodine absorption values were nearly
similar between one month and six months, but higher at twelve

months. Increased iodine values were found both in the outside fat

 

o ,,
V , o . . ,
n
I .~
, , , . , .

 

. , , , .
.
e
u
o , o
, _ _ , . , j ,
. ,
, , r
, - . . . .. -.
. 1 , j '1‘
, J . _ n . ‘x
.
. L . .
, , l - ~ ~
I ‘ \ .
O - .
- . ,7 _ .
, .4 - a e , o 3 .
—
._ . _ . -_ .», _ ~
-
. . .
v
, ,- - . .
. . . . .
—-.
‘ , e C o
a . - - - .—
g . w . \ ,
~, , .. . s
n. , , " .. , e \ . ,

   

TABLE IV

43

CHLORIDE. SOLUBLE NITROGEN AND TOTAL NITROGEN
ANALYSIS

 

Per Cent Chloride
(Fat and Mois-

Per Cent

Per Cent

 

 

 

Ham Code ture Free) Soluble Nitrogen Total Nitrogen
NO. No. 1 MO. 6 MO. 1 Mo. 6 MO. 1 MO. 6 MO.
53 1 15.87 10.06 0.74 1.08 3.46 3.85

250x 2 13. 89 13. 86 0. 99 1. 20 3. 66 4. 54

462 3 17. 4O 19. 44 l. 02 1. 80 4. 35 4. 37

552 4 14. 94 12. 22 0. 81 1. 32 4. 38 4. 77

570 5 12. 84 11.86 0.85 1.19 3.82 4.66

572 6 10. 18 10. 82 0. 78 1. 06 3. 36 4. 66

588 7 18.94 20.36 1.21 1.24 3.91 5.42

705 8 9.26 14.66 1.18 1.12 4.12 4. 78

721 9 11.16 12.79 1.06 1.60 4.59 4.99

731 10 13.51 14.27 1.31 1.27 4.11 4.61

771 11 11.32 11.38 1.00 1.18 4.84 4.81

941 12 14. 05 17.38 0.86 1.16 4.27 3.98

Average 13. 61 14.09 0. 98 1. 27 4. 07 4. 62

MeanDifference + 0.48 +0. 29 +0. 55

12 MO. 12 Mo. 12 MO.

228 1 17.41 15.30 0.88 1. 55 3. 28 4.72

551 2 12.18 11.16 1.10 1.58 3.89 5.60

556 3 11.30 16.51 0.84 1.57 4.20 5.21

590 4 18. 27 22. 21 0. 99 l. 41 3. 66 5. 26

606 5 10.20 11.35 1.06 1.63 4.31 5.40

656 6 18. 50 20. 55 1.19 1. 48 3. 82 5. 38

681 7 20. 06 20. 10 0. 87 1. 46 4. 01 4. 97

682 8 18. 68 14. 68 0. 92 1. 46 3. 86 4. 76

696 9 12. 34 23.01 0.94 1.52 4.36 5.77

781 10 14.97 16.40 1.03 1.31 4.56 5.10

784 11 11.34 9.08 0.76 1.49 3.98 5.22

833 12 12. 54 12. 82 l. 04 1. 64 4. 68 5. 00

Average 14. 82 16.10 0.97 1.51 4.05 5.20

+0. 54

Mean Difference + 1. 28

+1.15

 

TABLE V

pH. LACTIC ACID AND GLUCOSE ANALYSIS

 

 

 

Per Cent
Ham Code pH Lactic Acid1 Per Cent Glucose
No. NO. 1 Mo. 6M0. 1 MO. 6M0. 1 MO. 6 Mo.
53 l 5.35 5.57 0.95 0.68 0.48 0. 58
250x 2 4.98 5. 56 0.95 0.70 0.31 0. 48
462 3 6. 25 5. 61 o. 87 0.65 0'. 33 0.42
552 4 7.72 5.60 0.89 0.86 0.19 0.28
570 5 5.63 5.96 0.75 0.79 0.12 0.16
572 6 5.94 5.80 0.64 0.72 0.11 0.16
588 7 5.76 5.86 0.85 1.29 0. 10 0.33
705 8 5.86 5.60 0.66 0.70 0.21 0.20
721 9 5.92 6.05 0.74 0.34 0.38 0 13
731 10 6.50 5.85 0.30 0.84 0.11 0.17
771 11 6.04 6.08 0.74 0.72 - 0.15
941 12 6.20 5.70 0.40 0.66 0. 09 0.16
Average 6. 01 5. 77 0. 73 0, 74 0. 22 0. 27
Mean Difference -0. 24 +0. 01 +0. 05
12 Mo. 12 MO. 12 MO.

228 1 5.80 5.85 1.11 1.33 0.46 0.61
551 2 6.25 6.19 0. 66 0.71 0.12 0.80
556 3 5. 62 5. 86 0. 90 0. 65 0. 39 0. 63
590 4 5. 76 5. 88 0. 85 0. 62 0.18 0. 23
606 5 5. 62 6. l6 0. 84 0. 58 0. 24 0. 29
656 , 6 5.57 5.90 0.62 0.36 0.11 0.25
681 7 5.38 5.77 0. 68 0.52 0.26 0.36
682 8 5. 60 6.12 0. 72 0. 36 0. 46 0. 36
696 9 6. 15 5.70 0.59 0.63 0.31 0.27
781 10 6. 02 5.77 0.62 0.72 0.46 0.31
784 11 5.63 5.85 0.94 0.71 0.29 0.29
833 12 6. 00 5. 82 0. 68 0. 60 0. 56 0. 38
Average 5. 78 5. 90 0. 77 0. 65 0. 32 0. 40
Mean Difference -0. 12 -0. 08 +0. 12

 

1 Read at 570 Mu on model DU Beckrnan SpectrOphotometer.

TABLE VI

GLYCEROL AND ORGANIC MATTER ANALYSIS

45

 

Per Cent Glycerol1

 

 

 

Ham NO. Code No. Organic Matter2
1 Mo.
1 0.15 3. 75
2 0.14 3. 50
3 0.10 3. 08
4 0.10 2. 29
5 0.13 2. 50
Average 0. 12 3. 02
6 Mo.

53 1 0. 27 4. 38
250x 2 0. 23 5. 29
462 3 0. 21 4.92
552 4 0. 27 5. 00
570 5 ' 0. 36 4. 00
572 6 0. 27 2. 50
580 7 0. 31 4. 50
588 8 0. 28 4. 38
705 9 0. 26 4. 58
721 10 0.44 3. 33
731 11 0. 21 3.12
771 12 0. 29 4. 17
941 13 0. 34 3. 54
Average 0. 29 4. 13
Mean Difference +0. 17 +1. 11

 

TABLE VI CONTINUED

46

 

 

Ham NO. Code No. Per Cent Glyceroll Organic Matter2
12 MO.

228 l . 0. 33 6. 79
551 2 0. 50 4. 38
556 3 0. 42 6. 96
580 4 0. 53 4. 79
590 5 0. 44 4. 96
606 6 0. 62 5. 96
656 7 0. 51 4. 75
681 8 0. 33 5. 83
682 9 0. 37 4. 38
696 10 0. 45 5. 62
781 11 0. 37 5. 29
784 12 0. 36 5. 88
833 13 0. 40 6. 38
905 14 0. 51 5. 33

Average 0. 54 5. 52

Mean Difference +0. 42 +2. 50

 

1 Values read on Beckrnan model DU SpectrOphotometer at 525 Mu.

Milliequivalents dichromate reduced per gram of ham. Values

read at 650 Mu.

47
and the fat within the muscle. Linolenic acid values increased at
six months and oleic acid decreased. However, the linolenic values
were of such small magnitude that a slight difference could cause a
significant change (See Table VII).

Short'chain fatty acids. The total acid value for one month

 

was low and the acid was separated only with the 75 per cent
chloroform - 25 per cent butanol solvent mixture.

The separation was complete within this solvent mixture; the
peak fraction occurring in the fifth fraction collected. This
corresponded to the chromatographic separation of succinic acid as
separated from a mixture of acids and as a single acid. A recovery
of 91 - 94 per cent was Obtained for a known quantity of succinic
acid from be known acid mixture and for the single acid.

Chromatographic separation of acids from hams stored six
months yielded a significant increase in total acid. The results
obtained were quite erratic between hams. However, duplicate
samples yielded essentially the same peak values. Extracts from
five Of the hams contained acid separated with 85 per cent chloro-
form ," 15 per cent butanol solvent mixture. The most acid was
extracted with the fourth fraction. Acetic acid in known quantities
and chromatographically separated as described above for succinic
acid gave similar results. A yield Of 96 - 97 per cent was Obtained.

Values are shown in Table VIII for the 75 per cent chloroform - 25

48
TABLE VII

UNSAT UR ATED FAT T Y ACIDS

 

Iodine Number Per Cent Linoleic Per Cent Linolenic

 

 

 

Ham Code (Fat in Lean) Acid Acid

NO. NO. 1 Mo. 6 MO. 1 MO. 6 Mo. l‘Mo. 6 MO.

53 1 - 61.98 - 10.11 .. 0.26
250x 2 - 59. 59 - 10. 56 - 0. 33
462 3 65. 59 63.48 7.71 7. 86 0.70 0.70
552 4 64. 07 62. 38 7. 77 7. 75 0. 54 0. 51
570 5 60. 14 61. 22 6. 02 4. 30 0. 19 0. 05
572 6 60. 09 62. 58 4.18 7. 20 0. 00 0. 06
588 7 59.34 60.88 4.95 7. 63 0. 04 0. 30
705 8 65. 76 64. 78 7.15 8. 26 0. 34 0. 53
721 9 62. 38 67. 29 6. 58 9. 96 0. 38 0. 67
731 10 64.34 62.08 6.89 7.49 0. 17 0.59
771 11 67.27 62.43 11.00 10.10 0. 28 0.71
941 12 61. 18 63.32 5.89 6.81 0. 00 0.35
Average 63. 02 62. 67 6. 81 8. 17 0. 26 0. 42
Mean Difference - 0. 35 +1. 36 +0. 16

12 Mo. 12 Mo. 12 MO.

228 1 - 73. 02 - 11. 30 - 0. 23
551 2 64. 19 63. 59 6. 46 7. 60 0. 27 0. 00
556 3 64. 07 71. 78 5. 52 6. 58 0. 12 0. 00
590 4 60. 02 64. 67 5. 14 6. 97 0. 04 0. 08
606 5 64. 94 62. 86 4. 00 5. 64 0. 09 0. 00
656 6 59. 85 61. 32 4. 73 6. 06 0. 06 0. 00
681 7 61. 75 62. 67 4. 42 7. 76 0. 08 0. 23
682 8 62. 55 63. 60 7. 86 7. 46 0. 37 0.13
696 9 66. 20 70. 33 9. 54 9. 21 0. 44 0.18
781 10 63. 00 63. 13 7. 26 8. 38 0. 24 0. 00
784 11 64. 9-1 65. 23 6. 35 8.14 0. 16 0. 00
833 12 68.17 69. 94 6. 87 10. 45 0. 16 0. 22
Average 63. 60 66. 01 6. 20 7. 96 0.18 0. 09
Mean Difference + 2. 41 +1. 76 -0. 09

 

49

TABLE VII CONTINUED

 

 

 

 

 

Per Cent Per Cent Oleic Per Cent Saturated

Ham Code Arachidonic Acid Acid Acids
No. NO. *1 MO. 6 MO. 1 Mo. 6M0. 1 MO. 6 MO.
53 l - 0. 85 - 46. 64 - 44. 13
250x 2 - 1. 08 - 40. 01 - 48. 01
462 3 2.26 1.10 51.48 48. 57 37. 88 41.77
552 4 2. 63 1. 32 44. 22 47. 30 44. 84 43.12
570 5 0. 61 0. 82 52. 51 56. 24 40. 86 38. 60
572 6 0. 93 0. 74 54. 97 52. 18 39. 92 39. 81
588 7 1. 29 1. 31 50. 67 46. 58 42. 90 44. 18
705 8 1.88 1.49 51. 23 48. 28 39.40 41.43
721 9 1.24 1.97 54.14 45.44 37. 66 41.97
731 10 1. l3 1. 67 53. 26 45. 98 38. 55 44. 26
771 ll 1. 09 2. 49 42. 34 37. 70 45. 28 49. 00
941 12 0. 35 1. 22 54. 89 51. 13 38. 87 40. 49
Average 1. 34 1. 34 50. 97 47. 17 40. 62 43. 06
Mean Difference 0. 00 - 3. 00 + 2. 44
12 MO. 12 MO. 12 MO.
228 l - 2. 23 - 49. 49 - 36. 76
551 2 1.62 0.93 51. 56 51.98 40.09 39.49
556 3 1. 49 0. 99 51. 89 62. 92 40. 98 29. 50
590 4 1. 05 1. 38 52.39 52. 53 41. 38 39. 04
606 5 1.44 1. 33 58. 56 53. 63 35. 90 39. 40
656 6 0. 72 0. 94 54. 19 52. 52 40. 30 40. 49
681 7 0. 74 1. 28 56. 80 48. 63 37. 96 42. 09
682 8 1. 75 1. 20 46. 13 50. 90 43. 89 40. 32
696 9' 1. 75 1. 81 47.78 52.42 40.49 36.38
781 10 1. ll 0. 81 52. 73 50. 34 38. 66 40. 47
784 11 l. 75 0. 88 47. 78 52. 90 40. 49 38. 08
833 12 0. 98 .1. 60 57. 87 50. 15 34. 12 37. 58
Average 1. 31 1. 28 52. 52 52. 37 39. 48 38. 30
+0.10 + 0. 15 - 1. 18

Mean Difference

 

 

50

TABLE VIII

MILLIEQUIVALENTS 0F SHORT CHAIN FATTY ACIDS
PER GRAM or HAMI

 

Ham Code Total Acid

Solvent Mixturesz

 

 

No. NO. 1 MO. B15 320 B25 B30 B40
1 . 0041 0 0 . 0041 0 0.
2 . 0087 0 0 . 0087 0 0
3 . 0017 0 0 . 0017 0 0
4 . 0087 0 0 . 0087 0 0
5 . 0096- 0 0 . 0096 0 0
Average . 0066
6 MO.

53 1 . 0640 0 0 . 0310 . 0330 0
250X 2 . 0830 . 0080 0 0 . 0750 0
462 3 . 0440 0 0 . 022,0 . 0220 0
552 4 . 0610 . 0030 0 . 0270 . 0320 0
570 5 . .0350 0 0 . 0160 . 0190 0
572 6 . 0170 0 0 . 0170 0 0
580 7 . 0580 . 0020 0 0 . 0510 . 0050
588 8 . 0370 . 003.0 0 . 0310 . 0030 0
705 9 . 0710 . 0040 0 . 0410 . 0100 . 0100
721 10 . 0290 0 0 . 0260 . 0260 . 0030
731 ll . 0260 0 0 . 0130 . 0130 ., 0130
771 12 . 0460 0 0 . 0390 . 0390 . 0070
941 13 . 0460 0 0 . 0460 . 0460 0
Average . 0475

MeanDifference + 0. 04

 

 

ll

TABLE VIII CONTINUED

51

 

Sglv ent Mixture s 2

 

 

Harn Code TOtal Acid

NO. No. 12 MO. * 1315 320 B25 B30 B40
228 1 .1000 .0050 o .0300 .0400 .0250
551 2 .0900 .0100 .0100 0 .0600 .0100
556 3 .0650 .0150 0 .0100 .0400 0
580 4 .0435 .0025 0 0 .0410 0
590 5 .0850 .0100 .0150 0250 .0200 .0150
606 6 .0440 .0040 0 0400 0 0
656 7 .0450 '.0200 o 0150 .0050 .0050
681 8 .1300 .0200 .0650 0250 .0200 0
682 9 .1340 .0050 0 .0650 .0550 .0090
696 10 .0600 .0150 0 0200 .0250 0
781 11 .0400 .0050 0 0350 o 0
784 12 .0650 0 0 .0450 .0150 0
833 13 .0450 .0050 0 0250 .0100 .0050
905 14 .0450 .0050 0 0150 .0150 .0100
Average . 0708

Mean Difference +0. 064

 

1 Chromatographic separation short chain fatty acids.
2 The B subscripts represent the per cent butanol in chloroform Of
the solvent mixture.

52
per cent butanol mixture as described for the one month hams.
Eight hams contained acid extracted with 30 per cent butanol -
chloroform mixture. This acid corresponded to lactic acid.
Duplicate samples of lactic acid gave 80 to 85 per cent recovery
with the same peak values as the ham extract. The peaks were not
quite as sharp as with the other acids, but amount of recovery fell
within the above range for a number of known samples. Duplicate
samples on the ham extracts also gave about the same recovery of
lactic acid. The acid extracted with 40 per cént butanol - chloro-
form mixture was also quite erratic. A known acid could not be
found which corresponded to this acid. The difference between
peak fractions of "lactic acid" and the unknown acid was constantly
nine fractions. Also, when this acid was presentithe peaks were
sharp, the quantity of acid, however, was usually small.

One acid was separated at twelve months that was not found
at one or six months. This acid corresponded to glutaric acid. A
recovery Of 93 - 94 per cent was obtained with a good sharp peak.

The 15 per cent butanol - chloroform solvent liberated acid
from every ham except one (Table VIII).

The statistical summary of the data is presented in Tables IX

and X.

53

TABLE IX

STATISTICAL ANALYSIS OF THE DIFFERENCES OF TEST
FACTORS AT PROGRESSIVE STORAGE PERIODS

 

"t" Values Obtained for the
Differences From 1 Month Difference Between

 

 

Test Factor 1 Months 12 Months 6 and 12 Months
Flavor 0. 2647 j 2. 7444* l. 3976
Tenderness 1. 0347 0. 7270 0. 0391
Saltiness 2. 9431* 6. 3731** 3. 4282**
Moisture -5. 1432** -8. 9344** 2. 1025*
Fat 2.1413 0.3419 1.2426
Salt (Fresh Basis) 3. 2574** 4. 9708** 3. 1380**
Chloride (Dry) 0. 5810 1. 1324 1.3044
Soluble Nitrogen 3. 9804** 12. 5290** 2. 1678
Total Nitrogen 3. 5942** 9. 2605** 2. 1535
Peroxide 3. 0093* 2. 9847* 2. 3033*
Free Fatty Acid 9. 6855’” 9. 0909*,“ 3. 8832’"
Iodine NO. (Fat) -0. 3270 3. 6704** 1.5212
pH -1. 0258 -1. 4006 0.3333
Lactic Acid 0. 4684 1. 2541 0. 1727
Glucose 1. 0717 1'. 7686 0. 6502
Iodine NO. (Lean) -o. 3461 2. 5863* 0. 8234
Linoleic Acid 1. 7337 1.6630 0.0465
Linolenic Acid 3. 3938** -2. 3777* 2. 8640*
Arachidonic Acid 0. 4022 0. 7831 0. 0198
Oleic Acid —2. 4236* 0. 1294 1.0640
Saturated Acid 1.0986 -0. 4727 1.8064 .
Glycerol 92. 7222’" 138. 5217** 3. 6466**
Organic Matter 6. 3581** 11. 2574’” 3.1625**
Separable Acids 8. 8364” 8. 2619" 1. 4444

 

1 Student's "t" test of significance.
* = significance at . 05 level; ** = significance at . 01 level.

I

TABLE X

CORRELATION COEFFICIENTS FOR TEST FACTORS

 

Correlation Coefficients

 

 

6 Months 12 Months
Flavor - Saltiness +. 5071 +. 5475*
Flavor — Salt (Fresh) +.6422* +. 6570*
Flavor - Soluble Nitrogen -. 1594 -. 0163
Flavor - Free Fatty Acid -. 0019 +. 4347
Flavor - Glycerol +. 2559 +. 0237
Flavor - Organic Matter +. 3574 -. 0861
Flavor - Total Separable Acid +. 3571 -. 2063
Saltiness - Moisture -. 3503 —. 2199
Saltiness - Salt (Fresh) -. 1193 +. 2960
Moisture - Salt (Fresh) -. 0814 -. 0918
Peroxide No. - Free Fatty Acid +. 1513 +. 1177
Free Fatty Acid - Iodine No. +. 2230 +. 0403
Free Fatty Acid - Glycerol +. 1705 +. 0740
i Iodine NO. (Lean) - Oleic Acid -. 1388 +. 6985*
Iodine No. (Lean) - Linoleic Acid +. 6520* -. 1565
Iodine NO. (Lean) - Linolenic Acid +. 2251 -.9045**

 

* = significance at . 05 level; ** = significance at . 01 level.

 

 

DISCUSSION OF RESULTS

The validity of the results for the taste panel scores is based
on the agreement Of the tasters in the evaluation of aged flavor,
tenderness and saltiness. Objective values Obtained by chemical
analysis are real values. Any attempts Of correlation between
subjective scores and Objective values, however, must assume that
the subjective values are also real values. This is true since the
quality value of a food product is weighed heavily by its accept-
ability in terms of a preferred standard.

The taste panel scores within any sampling period did not
vary appreciably. To varify this conclusion, the taste test scores
were adjusted comparable to values Obtained had the same tasters
been used for a complete sampling period. That is, for one month,
six months or twelve months. The formula used was as follows:

S _-§ :1: missing J's - (no. of missing J's x (J)
a - no. Of J's present

 

Sa = adjusted value; S = mean of the Observed values and J =
judge mean reference point. The values thus Obtained as correction
factors were between :I: . 02 to . 03 of the Observed values. There-
fore, no adjustment Of scores was necessary. The fact that the

same judges were not available for every taste period did not

appreciably affect the evaluation score. The selection and training

.-q~.._. .i

("{3— .

 

 

56
of the panel was probably the reason for this close agreement in
scoring between panel members.

Although no difference was found between tasters, inspection
of the data indicates that high flavor ratings were given for some
one month Old hams. The reasons for this may be due to a tendency
to evaluate hams relatively within any one taste session. If some
difference in flavor is detected between succeeding hams there is
probably a tendency to score high or low depending on the relative
difference.

Of the factors studied, salt had the most influence on flavor
evaluation. This is reasonable since the salt concentration was
fairly high. Insufficient salt greatly influenced aged flavor scores
even though a separate rating was given for each factor. For
example, ham number six, Table I, has a flavor score of 1. 86, the
smallest saltiness score for that group, 3. 14 and the least salt as
determined chemically, 3. 44 per cent. It should be mentioned that
both ham pair mates were low in salt content. The range in scores
for saltiness was somewhat greater than for the other two factors
considered but this was mostly Offset by a corresponding high or low
value.

Tenderness scores were erratic only for a few hams. This
may have been due to the difference in samples rather than Opinion

differences. An attempt was made to trim the outside edge of the

57
cooked meat sample, but some difference in moisture content of
"bite" samples may have caused the variation. The differences
between groups of hams, however, indicated little difference in
tenderness.

Since there was an appreciable moisture decrease it is logical
to assume that the concentration of stable compounds should
increase on a fresh weight basis. This is the case with salt. The
concentration increased on a fresh basis, but did not change when
calculated on a dry basis. From a flavor standpoint Only the former
need be considered.

Soluble nitrogen, total nitrogen and free fatty acids increased
with storage time. This is in agreement with the work of Hunt,
Supplee, Meade and Carmichael (1939). While these compounds
increased quantitatively in an upward direction as did flavor score,
only free fatty acids were close to being significantly correlated
with flavor scores. A larger sample is necessary in order to
definitely establish if aged flavor is correlated with free fatty acid.

Peroxide content in the quantities found in these hams is
definitely not a factor that may be used to indicate aged flavor.

Lactic acid increases or decreases to a certain extent with
pH, but the differences were too small in this experiment to be

statistically significant.

58

Glucose values remained nearly the same during the entire
storage period. The color appeared normal in every ham, there-
fore, there were no measurable affects from glucose. In several
hams these values were higher than might be expected. The work
Of Lewis (1937) and Brady, Smith, Tucker and Blumer (1949) listed
lower values. However, lower storage temperatures were used
here than for the above studies.

A study by Corman (1948) indicated that in samples containing
nitrite some interference in the idometric determination of sugar
may result. To determine if nitrite caused erroneous readings in
this study, the entire group of twelve months samples were treated
with urea to eliminate nitrites as recommended by Corman. The
values thus obtained were nearly identical with those without treat-
.ment. Therefore, the nitrite content was not sufficient to cause
interference. When nitrites were added to samples in the amounts
used by Corman, interference was appreciable. The nitrite content
was quite low in all hams. The values were only 10 to 40 parts per
million with little change throughout the entire storage period.

The. method used for glycerol determination is dependent upon
the formation of formaldehyde. A consistant increase of "glycerol"
occurred with length Of storage period. Since glycerol may be
liberated with the hydrolysis Of triglycerides a correlation analysis

was conducted. These values were positive, but too small to be

 

 

 

illl

 

 

59
significant. It may thus be assumed that all Of the glycerol does
not come from the result of fat hydrolysis.

Inspection of the data presented in Table VI indicates that the
glycerol values fall quite closely within certain limits as follows:
below . 20 per 'cent, 1 month; . 20 - . 35 per cent, six months and
. 35 - . 60, twelve months. Aged flavor scores may not be arranged
in this manner, therefore, glycerol is a more predictable tool for
use in estimating storage time. It should be noted however, that
the differences between one month and six month hams were not
obtained by paired difference. The differences obtained are relative
between groups. Aged flavor scores are only associated with
glycerol values in the reSpect that both Show average increases with
time.

The iodine number of both the outside fat and the muscular fat
increased at the twelve months sampling period. Anaerobic con-
ditions were approximated in each case, since the skin covered the
outside fat during storage, and the sample was removed near the
center of the ham. Jensen (1945) quotes Bach and Sierp (1924) in a .
statement to the effect that under certain conditions of anaerobiosis,
carbon dioxide is split off and the fatty acids are changed into
hydrocarbons resulting in a lower sponification and higher iodine
number than the original fat. The saturated acids here, however,

showed very little change from one month to twelve months.

60

The peroxide increase was higher at six than at twelve months.
This is in agreement with the iodine values. Pork fat exposed to
aerobic conditions normally increases in peroxide content during
the induction period. The results Of this study are, therefore,
somewhat analogous to those quoted by Jensen (1945).

It has been previously mentioned that linolenic acid increased,
but the quantity of this acid was so small that a slight change would
be significant. It may have happened that the structure of this acid
was altered in such a way that it gives a Spectral reading similar to
oleic acid. The quantity of Oleic acid is determined by the magni-
tude of the iodine number and the quantity of other unsaturated acids
as they are determined SpectrOphotometrically. It is Obvious that
the accuracy of the Oleic acid determination and any interpretation
concerning this acid is dependent upon the accuracy of the other
dete rminations .

Other studies have indicated that the Spectral characteristics
of methyl linoleate and methyl linolenate are changed following
alkali - isomerization (Swain and Brice, 1949; Privett, 1951 and
Privett and Lundber g, 1951). Arachidonic and linoleic acid charac-
teristics were also affected. NO indication of a Similar reaction
seems likely in this study. The trends in fatty acid content do not

indicate their association with aged flavor in the present study.

61

Chromatographic separation of short chain fatty acids indi-
cated one Specific trend. The acid separated with the 85 per cent
chloroform - 15 per cent butanol was not present in one month Old
hams, only occasionally in Six month hams and in all hams except
one at twelve months. This seems to be a fairly good criteria on
length of storage period. The other acids did not appear consistent-
ly enough to draw valid conClusions.

From the data it appears that aged flavor scOres are best
reflected by the salt content of the hams.- An equation formulated to
predict flavor scores should, therefore, have a salt factor included.

From the data presented the following equation applies quite
well for the selection of hams on the basis Of aged flavor scores:

Aged flavor = values > 4% salt + values > 4% free fatty
acid + values > . 35% glycerol

This equation eliminates all one month Old hams, all except
two six months Old hams and most of the lowest flavor scored hams
in the twelve month group. A less critical equation would contain
the following:

Aged flavor = values > 4% salt + values > 4% free fatty
acids

Most Of the lowest scored hams in the six months and twelve
months group are eliminated by the use of this equation. If a 5 per

cent salt value is substituted for 4 per cent salt in the above

62

equations, results are just as satisfactory and somewhat more
discriminating. Since one or two high scoring hams are eliminated
at this salt level, the 4 per cent level may be more practical. A
larger number Of hams would probably facilitate the use of more
definite limits on the factors used in the equations. An upper salt
linlit should be included as well as the lower limit. There is some
indication from the flavor scores that 10 per cent salt Should be the
upper limit. The moisture content and possibly the fat content will
influence the limits under a given set of conditions. The most
uniform moisture and fat content was found for the twelve months
old hams in this study. This is no doubt one reason for the more
uniform flavor scores.

The extent Of aged flavor development is indicated comparable
to the amount deve10ped by hams aged about five months at 21. 11° C
(70° F.) and 70 per cent relative humidity.

For future work, the test factors included in the formula pre-
sented should be determined on a large number Of hams. The
equation may then be applied to these values and by this means
select the hams with probable high aged flavor. The entire group of
hams would be scored by the taste panel as described in this study.
Hams given high flavor scores by the taste panel could be compared
with those selected by the prediction equation. The reliability of

the prediction equation could thus be established.

SUMMAR Y

Fifty-four hams were dry cured and stored at approximately
4. 4° C (40° F. ) until they were sampled chemically and by taste.
testing. Twenty-seven hams were sampled after storage for, 1
month, thirteen of their pair mates at 6 months and the remaining
fourteen at 12 months. The identity of the pair mates was maintain-
ed throughout the study in order that chemical values and taste test
scores could be recorded for each Specific ham. The differences
between one month and six months and twelve months were calcu-
lated; the differences were analyzed statistically and tests Of
significance applied. Correlation studies were conducted on taste
test scores and some of the chemical compounds.

Taste tests. Flavor increases with each sampling period,

 

but was significant only at twelve months.
Tenderness did not change to any appreciable extent.
Saltiness increased to a marked extent at each sampling
period, but there was a marked variation between samples.

Chemical tests. Salt, peroxides, free fatty acids, soluble

 

nitrogen, total nitrogen, glycerol, water soluble organic matter and
total water soluble chromatographically separable acid increased
with each storage period. Moisture was found to decrease with

length Of time in storage.

64

Saturated acids increased ,at six months but not at twelve
months.

Iodine absorption number decreased for external adipose
tissue and muscular fat at six months, but increased at twelve
months.

Oleic acid decreased at six months but increased slightly at
twelve months.

Linolenic acid increased at six months but decreased slightly
at twelve months.

Flavor was positively correlated with saltiness taste scores
' and chemically determined salt values. Free fatty acid values were
positively correlated with flavor scores at twelve months but the
values were slightly low to be significant at the 5 per cent level.

A prediction equation suggested for evaluating aged flavor in
hams is as follows:

Aged flavor = values > 4% salt + values > 4% free fatty
acids + values > . 35% glycerol

When this equation is applied to the hams in this study, most
of the hams aged for twelve months are acceptable; all but two Of

the six months hams would be excluded and none of the one month

old hams would be retained.

65
An equation that will eliminate the hams lowest on the flavor
scale for six and twelve months is as follows:
Aged flavor = values > 4% salt + values 7 4% free fatty
acids
A sharper selection results when 5 per cent salt is substituted
for 4 per cent, but in application 4 per cent may be the most satis-

factory factor to use.

BIB LIOGR APHY

Alexander, L. M., Clark, N. G., and Howe, P. E. Methods Of
cooking and testing meat for palatability. Sup. to Nat'l. Proj.
Coop. Meat Invest. Rev. ed. U. S. Bur. Home Econ. and
Bur. An. Indust. 1933, 36 pp.

Bach and Sierp. Untersuchungen iiber den anahroben Abbou
organischer Stoffe durch Bakterien des Klirchlammes.
Centbl. f. Bakt. Abt. II, 62, 1924. (quoted by Jensen, L. B.
Microbiology of meats. The Garrard Press. ed. 2, 1945.
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