DETERMINATION OF OXYGENATION RATES 1N
PORK, BEEF. AND LAMB BY MUNSELL ANS}
REFLECTANCE COLORIMET RY

Thais. fu- tho Degree of M. S.
MlQ'flGAN STATE UNNERSITY
Martin Charies Haas
1963

v”

This is to certify that the

thesis entitled

DETERMINATION OF OXYGENATION RATES IN PORK, BEEF,

AND LAMB BY MUNSELL AND REFLECTANCE COLORIMETRY

presented by
Martin Charles Haas

has been accepted towards fulfillment
of the requirements for

M.S. degree in Food Science

/§7/éa/TZZD

/Major professor

 

Date-.MagL 28; 19 63

0-169

LIBRARY

Michigan Sm:
University

 

ABSTRACT
DETERMINATION OF OXYGENATION RATES IN PORK, BEEF, AND LAMB
BY MUNSELL AND REFLECTANCE COLORIMETRY

by Martin Charles Haas

An experiment was conducted to determine the rate of oxygenation

known in the meat industry as "blooming" using the langissimus dorsi

 

(L.D.) muscle of pork, beef, and lamb. The rate studies were made by
Munsell Calorimetry and the ‘ Gardner Color Difference Meter. The
procedure involved making an initial reading an a cross section of the
L.D. followed by readings at fifteen minute intervals up to two hours an
park and lamb and three hours on beef. Maximum oxygenation was consi-
dered to be the color evaluation at twenty-four hours. Upon obtaining
Munsell hue, value, and chroma renotations by disk calorimetry, conver-
sions were made to Index of Fading. Color Difference Meter measurements
were interpreted by aL, aL/bL ratio, and total light difference. Accor-
ding ta Index of Fading, 87% of the color change in park occurred in one
hour. In beef, 45% of the color change was obtained in one hour, 74% in
two hours, and 90% in three hours. In lamb, 67% of the change occurred
in one hour and 95% in two hours. According to reflectance, 55% of the
color change in park occurred in one hour based on change of aL. In beef,
74% of the change occurred in one hour, 88% in two hours, and 96% in
three hours. In lamb, 78% of the change occurred in one hour and 86% in
two hours.

Several useful relationships were found employing Munsell and re-

flectance calorimetry. In reflectance, aL was shown to compare closely

Martin Charles Haas

with total light difference on a percent color change basis. Thus, the

use of aL as an indication of color change eliminates the labor involved

 

in calculating \éLz +40 aLz + AtbLZ. A highly significant negative car-

relatian was also found between Index of Fading of the Munsell system

and aL of the Gardner system. Therefore, aL could be used as indication

of oxygenation rates.

DETERMINATION OF OXYGENATION RATES IN PORK, BEEF, AND LAMB

BY MUNSELL AND REFLECTANCE COLORIMETRY

By

MARTIN CHARLES HAAS

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE
Department of Food Science

1963

(F 7 S 7‘“ (‘6

ACKNOWLEDGMENT

The author desires to express his appreciation to Lyman J. Bratzler,
Professor of Meats in the Department of Food Science for his technical
aid, advice, interest, and c00peration facilitating completion of this
thesis.

The author also wishes to acknowledge Mrs. Beatrice Eichelberger
for her c00peration in typing this thesis.

Finally, the author would like to eXPIESS‘mOSt sincere appreciation
to his parents whose assistance and understanding were unfailing through-

out his education.

ii

TABLE OF CONTENTS

INT ROD UCT ION 0 o o o o o o o o o o o 0

REVIEW OF LITERATURE . . . . . . . . .

The Identity of Myoglobin . . . .

Structure and Composition of Myoglobin . . . . . . .

Theory of Oxygenation . . . . . .

Factors Determining the Rate of Oxygenation . . . . .

Color Measurements as an Analytical Tool . . . . . .

EXPERIMENTAL PROCEDURE . . . . . . . .
Source of Meat . . . . . . . . .
Sampling Procedure . . . . . . .
Color Measurements . . . . . . .

l. ‘Munsell Disk Calorimetry
2. Gardner Color and
3. SpectrOphotametry . . .

Statistical Analysis . . . . . .

RESULTS AND DISCUSSION . . . . . . . .
Effect of Oxygenation Measured by

Effect of Oxygenation Measured by

Color Difference Meter

the Munsell System

Reflectance . . . .

Percent Change in Color Due to Oxygenation . . . . .

Conversion of Reflectance Data to Munsell Renotations

Correlation Between Methods of Color Analysis . . . .

Advantages and Limitations to Methods of Color Analysis

iii

Page

13

20
20
20
20
20
23
24

26

28
28
29
33
42
49

54

Page

SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . . . . . . 56

BIBL IOGMPIIY . C C O O O O O C C C 0 C C O O O O O O O O O O O O 58

APPENDIX 0 O O O C I O O O O O O O O O 0 I O O O I O O I O O O O 6 2

iv.

Table

LIST OF TABLES

Summarized Munsell calorimetry data for pork, beef, and

lamb . . . . . . . . . . .
Summarized reflectance data
Summarized reflectance data
Summarized reflectance data

Comparison of percent color

reflectance systems . . . . . . . . . . . . . . . . . .

Summary of Munsell data obtained by disk calorimetry and
by conversion from reflectance for beef . . . . . . . . .

Summary of Munsell data obtained by disk calorimetry and

for park . . . . . . . .
for beef . . . . . . . .
for lamb O O O O O O O 0

change between Munsell and

by conversion from reflectance for lamb . . . . . . .

Correlation of Munsell and reflectance data . . . . .

Page

30
34
35

36

39

47

48

50

Graph

Relationship
Relationship
Relationship
Relationship
Relationship
Relationship

Relationship

of

of

of

of

of

of

of

LIST OF GRAPHS

Index of Fading with time . . . . . . .
3L with time . . . . . . . . . . . . .
percent change in aL with time . . . .
percent change Index of Fading with time
Index of Fading and 3L in park . . . .
Index of Fading and 3L in beef . . . .

Index of Fading and 3L in lamb . . . .

vi

4O
41
51
52

53

Appendix

1

I

I
II
II
II
III
III
III
IV
IV

IV

VI
VI
VI

VII

VIII

Park

Park

Park

Park

Park

Park

Beef

Beef

Beef

Beef

Beef

Beef

Lamb

Lamb

Lamb

Lamb

Lamb

Lamb

data

data

data

data

data

data

data

data

data

data

data

data

data

data

data

data

data

data

LIST OF APPENDIX TABLES

obtained
obtained
obtained
obtained
obtained
obtained
obtained
obtained
obtained
obtained
obtained
obtained
obtained
obtained
obtained
obtained
obtained

obtained

by-

by
by
by
by
by
by
by
by
by
by
by
by
by
by
by
by

by

'Munsell calorimetry . . . . . .
'Munsell calorimetry (continued)
'Munsell calorimetry (continued)
reflectance . . . . . .4. . . .
reflectance (continued) . . . .
reflectance (continued) . . . .
'Munsell calorimetry . . . . . .
iMunsell calorimetry (continued)
‘Munsell calorimetry (continued)
reflectance . . . . . . . . . .
reflectance (continued) . . . .
reflectance (continued) . . . .
‘Munsell calorimetry . . . . . .
Munsell calorimetry (continued)
'Munsell calorimetry (continued)
reflectance . . . . . . . . .

reflectance (continued) . . .

reflectance (continued) . . . .

Correlation of myoglobin concentration and Index of
Fading in lamb .

Correlation of myoglobin concentration and aL in lamb

vii

Page

0 62

63

64

65

66

67

. 68

69

7O

71

. 72

73

. 74

75

76

77

. 78

79

80

81

INTRODUCTION

Color is an important attribute of meat recognized as a criterion
of quality (Bull, 1951). Meat color is known to develop through defin-
ite changes depending upon the status of the pigment myoglobin (Brooks,
1929). When initially exposed to the air, a purple red pigmentation
is observed due to the presence of myoglobin in its reduced form. After
a short time the meat will become increasingly red due to the formation
of oxymyoglobin. This process is called oxygenation, which involves
the addition of an oxygen atom to the myoglobin (Lavers, 1948). Oxygen-
ation is known commercially as "bloom" and is exceedingly important in
consumer acceptance. During long exposure to the air, a brown pigment
called metmyoglobin is formed which is the result of an electron exchange
and is very undesirable in appearance to the consumer (Levers, 1948).
There are many factors which influence bloom, including concentration
of myoglobin in the tissue, oxygen pressure and penetration, relative
humidity, temperature, light, bacteria, and enzymes.

The objectives of this investigation were to determine the actual
rates of oxygenation of surface pigment in pork, beef and lamb using
Munsell Calorimetry and the' Gardner Color and Color Difference
Meter. These data can then be employed as a basis for characterizing
the color of freshly cut meat. Another purpose was to evaluate the ad-

vantages and limitations of these two methods of meat color analysis.

REVIEW OF LITERATURE

The Identity of Myoglobin

The color in meat muscle tissue is primarily due to the pigment myo-
globin. According to The Science of Meat and'Meat Products (1960), myo-
globin accounts for only 10% of the total iron in the live animal.
However, this text also reports that in well bled beef skeletal muscle,
approximately 95% of the iron has been determined as myoglobin. The
remaining 5% of pigmentation was stated to consist of cytochromes, red
heme pigments, vitamin B12 (which contains the same porphyrin ring as
the heme but contains cobalt rather than iron) and flavins. 'Morner
(1897) presented the first evidence demonstrating the existence of a
muscle pigment separate from blood hemoglobin on the basis of a study
on muscle extracts from dogs, cattle, and horses. He compared the ab-
sorption spectra and showed that there was a slight displacement of myo-
globin toward the red part of the spectrum. In 1932 Theorell succeeded
in crystallizing myoglobin from horse heart, proving that there was a
protein in muscle resembling the hemoglobin of blood but distinct from
it. Shenk, Hall, and King (1934) contributed further evidence that
muscle and blood pigments were separate entities by use of spectrophoto-
metry and reported that the maximum absorption for blood hemoglobin
occurred at 517 and 542 mu, while for muscle hemoglobin the similar peaks
were at 583 and 543 mu. They also indicated that the myoglobin content
in longissimus dorsi of beef could not be correlatedwith hemoglobin con-

tent in blood.

-3-

Structure and Composition of Myoglobin

Both hemoglobin and myoglobin are heme-proteins. Schweigert (1956)
indicated that a heme protein is comprised of a heme moiety which is an
iron containing porphyrin compound attached to a globin protein. The
heme consists of four pyrrole rings in the center of which is an iron
atom coupled to the four nitrogen atoms. The heme also contains four
methyl groups (CH3), two vinyl groups (-CH2 = CH2), two prapionic acid
radicals (-CH2 CH2 COOH), and four pyrrole rings (C4H5N) which in combin-

ation with the iron comprise the iron porphyrin ring as illustrated below.

L N's en...
HooC-(flicflg -——'~'(/ [L (E— °CH=CHa
chT/ \ = H
Hoofrmiullc CCHB

The Iron Porphyrin Ring or Heme (Schweigert, 1956)
The iron bound in the center of the porphyrin ring has six valences, but
only four are connected with the nitrogen atoms of the pyrole. Another
valence is bound to the protein component, globin, by means of an imidazoka'
group of a histidine molecule in the amino acid chain of the globin. (Ken-
drew, 1949). The sixth bond orbital provides for the complexing of an
atom which has an electron pair to donate to the iron as stated by Granick

and Gilder (1947). Thus, in oxygenation, oxygen is the electron donator.

Kendrew (1949) established the physicalshape of a myoglobin molecule
as two disks which are 57°A in diameter and 9°A thick, lie parallel to
each other, and are separated by a layer of crystallization about 6.6°A
thick. Each of the disks is formed by one polypeptide chain folded on
itself in four equal sections to form a flat disc of 43°A X 35°A X 23°A,
which was determined in Xray analysis by Kendrew (1958). The prosthetic
ferroheme is perpendicular to the plane of each disc and extends above
and below it.

There are many physical constants important in the characterization
of myoglobin. Kendrew (1949) established a sedimentation constant of
2.0 X 10-3. Bowen (1948) reported a molecular weight of 16,400, iron
content of .323 percent, and isoelectric point of 6.99.

The color changes occurring in meat are the result of the three forms
of myoglobin and their relative concentrations. These forms include myo-
globin (purple), oxymyoglobin (red), and metmyoglobin (brown). The
changes of myoglobin have been illustrated by Brown and Tappel (1958),
in which the porphyrin ring is symhiized by the four nitrogen atoms of

the pyrrole rings.

filo I.“ Glob”, GIDLN’I
N r N )\ N D |/V
\FC/ 0 \ 6/ ad 7" K/v
, // all I 3 Ion
AV/// §\\\TJ /’ N,//i\\\N \sfiafithHo \M./// Ff:\\hi

I
(ii [130

 

 

 

 

 

oxymyoglobin reduced myoglobin metmyoglobin

These authors further observed that the combination of oxygen with myo-
globin to form oxymyoglobin was a reversible step and was primarily
dependent on high oxygen availability. The formation of oxymyoglobin
involved a transfer of an oxygen atom and hence is called oxygenation.
At low partial pressures of oxygen, there will be a transfer of electrons
and metmyoglobin will be formed. Schweigert (1956) stated that the
presence of reducing conditions maintained myoglobin in the reduced state
and also converted metmyoglobin to myoglobin. An important factor
governing the color of pigment is the valence state of iron. As can be
observed, the iron is in the reduced state in myoglobin. In oxymyoglo-
bin the iron is also in the reduced ferrous state, but contains more
oxygen held.irl loose combination" In metmyoglobin, the iron has been
oxidized to the ferric state due to decrease in one electron. Lavers
(1948) stated that oxymyoglobin is not an intermediate in the formation
of metmyoglobin and has presented the pathway of discoloration as follows:

oxymyoglobin ----- -->‘ reduced myoglobin ------ >~metmyoglobin
Brooks (1929) affirmed that oxymyoglobin must be dissociated into oxygen
and myoglobin before metmyoglobin could be formed.

The total pathway of fresh pigment color changes has been determined

as follows according to The Science 2f_Meat and Meat Products.

-6-

oxygenation

>

Myoglobin <P--—-——-- oxymyoglobin
Red Fe+2

 

 

 

Sulfide
+
oxidation sulfidei- Reductants +
oxidation xidation
V L
Sulfmyoglobin ‘BCholemyoglobin
, green green
\\\\\\\§§Free and oxidizedgg’////
Porphyrins

Brooks (1929, 1931, 1935, 1948) extensively studied the oxidation
of both hemoglobin and myoglobin. He stated that the conversion of
myoglobin to metmyoglobin involves a valence change of the iron atom
and required one hydrogen equivalent of oxidizing agent for each atom
of iron in the myoglobin molecule. The establishment of an equilibrium
between oxygen, myoglobin, and oxymyoglobin is very rapid in comparison
with rate of oxidation. Furthermore, this oxidation to metmyoglobin
occurs at the maximum rate when oxygen partial pressure is law. He
stated there are three possible pathways postulated for the reaction
between myoglobin and oxygen depending on oxygen tension. These include:

1. Spontaneous decomposition of oxymyoglobin to metmyoglobin.

2. Oxygenation of reduced myoglobin to oxymyoglobin at high oxygen

partial pressure.

3. Oxidation of reduced myoglobin at low oxygen pressure.

Brooks has also stated that the pigment of muscular tissue is present

at the surface as oxymyoglobin, which gradually changes during cold

storage to metmyoglobin which is brown. The brown discoloration re-

sults from metmyoglobin formation, loss of moisture from the surface, and

disintegration of the globin components.

Theory of Oxygenation

In Fruton and Simmonds (1959), the physiological importance of hemo-
globin and myoglobin is explained to lie in their ability to combine
reversibly with oxygen. Hemoglobin acts as a transport for oxygen from
air to the tissue of animals by means of the red corpuscles in the circu-
latory system. They also state that on a stoichiometric basis one gram
of iron will combine with 400.9 m1 of molecular oxygen at standard temper-
ature and pressure. Accordingly, there is a shift in the absorption
spectrum for the conversion of myoglobin to oxymyoglobin. An interesting
aspect discussed by these authors in this conversion is the change in
electron status. Both myoglobin and oxygen are paramagnetic, Which means
that an electron is unpaired. The unapposed spin of this unpaired electron
confers a magnetic moment on the molecule and is attracted by an external
magnetic field. Oxymyoglobin is diamagnetic, because all the electrons
in the molecule are paired as indicated by a repulsion in an external mag-
netic field. Thus, there is a covalent bonding of the iron and oxygen
atoms. This equilibrium may be expressed in symbols by:

Mb + 02 {an} Mbo2

Kassoc = (MbOz)
(Mb) (02)

Since the concentration of oxygen is proportional to the partial pressure

of the gas according to Henry's Law, the term for concentration of oxygen

may be replaced by p02. The following relationship may then be established,
which is termed HUfner's equation. Details concerning this equation are

Mb 0
(Mb = Kassoc X P02

thoroughly explained in Lemberg and Legge's text, Hematin Compounds and
Bile Pigments.

If the percent of the total oxymyoglobin concentration is plotted
against the partial pressure of oxygen, Millikan (1937) demonstrated that
the curve will be a rectangular hyperbole. Such data are derived by equil-
ibration of a solution of myoglobin with a gas phase having a known partial
pressure of oxygen followed by analytical determination of oxygen in the
gas and liquid phases. Correction for the dissolved oxygen unbound must
be made. The rate of oxygenation will then follow the course illustrated

in the graph below.

   

.« B

50 / H: Mint/(obllh

6W / 5’2 Heme/alcb'm
% Mb02 /

‘fod /

/
20“
1 3°“ "CC As 39' '09

 

 

Rate of oxygenation of myoglobin in aqueous extract

Factors Determining the Rate of Oxygenation
l. Myoglobin concentration of tissue
The darkness of color depends on the concentration of myoglobin

in the tissue. Lawrie (1950) reported that wide variations occur between

muscles of the same animal. This was demonstrated by .465% in longissimus

 

dorsi, .610% in the diaphragm, and .705% in the psoas in beef. Shenk,

Hall, and King (1934) indicated that exercise may be a greater factor than
nutrition for myoglobin concentration. iMillikan (1939) demonstrated that
high concentrations of myoglobin are generally found in muscles requiring
slow repetitive activity of considerable force such as the heart muscles
of large animals, and leg muscles of running animals. Whipple (1926)
showed that age increased the myoglobin concentration. For example, beef
contains a range of 4 to 10 mg of myoglobin per gram of tissue, while veal
has about 1 to 3 mg/g. Mineral supplementation has produced contradictory
effects. In a study conducted by Niedermeier (1959) and substantiated by
Bray (1959), iron and copper additions to the feed were shown to greatly
influence the myoglobin concentration in veal muscle. In pork, however,
Henry (1959) demonstrated that zinc, iron, calcium, and copper supplemen-
tation produced no significant effect on myoglobin concentration, as indi-
cated by greater difference within treatment than between treatments.
Lawrie (1950) reported that park muscle can vary in color and still have
the same myoglobin content. He indicated that muscles appear much darker
at the pH 7.0 than at 6.3.
2. Oxygen pressure and penetration

Neil (1925) reported that no metmyoglobin can be formed in the
campkte absence of oxygen because no oxidizing agents are available to
oxidize the myoglobin to metmyoglobin. Brooks (1929) also indicated that
no metmyoglobin is formed from myoglobin stored in pure nitrogen storage.
Thus, the presence of an oxidizing agent such as oxygen is an obligate

requirement for the formation of the brown pigment metmyoglobin. Neil

-10-

and Hastings (1925) found that at 30°C (86°F) the rate of methemoglobin
formation was greatest when the partial pressure of oxygen was about 20
mm of Hg. Brooks (1929) also worked with hemoglobin solutions and found
that at 20 mm Hg pressure, the concentration of hemoglobin and oxyhemoglo-
bin were nearly equal. The rate of methemoglobin formation was monomole-
cular with respect to the hemoglobin at constant oxygen pressure.

Brooks (1935) reported that the concentration of oxygen in the muscle
tissue decreases in." proportion to distance from the surface. Brooks
(1929) found that tissue generally has a small oxygen uptake. As a result
a "steady state" will be reached in a sufficient amount of time where the
depth of oxygen penetration can be determined by the rate of diffusion of
oxygen into the tissues and the oxygen consumption of the tissues. He
further reported that the depth of oxygen penetration was determined by
the oxygen pressure in atmospheres at the surface of the tissue, the diffu-
sion coefficient of oxygen through the tissue, and the oxygen uptake of
the tissue. In 1935 he stated that the depth of oxygen penetration showed
a slow increase with time and decrease in temperature. He further found
that the depth of penetration was proportional to the square root of the

oxygen press ure 0

3. Effect of relative huuidity.
The production of undesirable pigment change can be closely
related to factors controlling loss of moisture from the surface of the
meat. In a study conducted by Brooks (1937), high humidities at 0°C pro-

duced discoloration by metmyoglobin in less than one month. At low humi-

-11-

dities browning occurred much more rapidly due to dehydration of the sur-

face and formation of metmyoglobin.

4. Effect of temperature

Probably the most important factor determining rate of oxygena-
tion is temperature. Brooks (1937) indicated that the oxygen pressure
required for Optimum methemoglobin formation is dependent on the tempera-
ture. Even the depth of oxygen penetration is inversely related to temp-
erature. Ramsbottom.and Koonz (1941) determined the relative concentration
of oxymyoglobin and metmyoglobin on the surface of steaks stored for one
year at 10°F and -30°F. By preparing extracts of the surface tissue and
determining absorption spectra, the sample stored at 10°F was found to
yield a curve similar to metmyoglobin. The curves obtained from samples
stored at -30°F indicated a mixture of oxymyoglobin and metmyoglobin.
Rikert (1952) found that meat stored at 34°F, 54°F, and 85°F resulted in
greater darkening as the temperature increased. The time required for the
return of the red color in the packaged meat was decreased as the temper-

ature increased.

5. Effect of light
Fresh meats, in comparison to cured meats, appear to be rela-
tively unaffected under normal display conditions of light according to
a study performed by Kraft (1954). He reported that the intensity of soft
white fluorescent light was unimportant in influencing the course of dis-

coloration of packaged fresh beef. Measurements of Spectral reflectance

-12-

as well as visible color changes indicated that ultra-violet light causes
rapid oxidation of myoglobin to metmyoglobin. Ramsbottom (1951) reported
that diSplay case lighting does not significantly discolor fresh meat
within the usual diSplay periods up to three days provided that there is
no significant microbial development. In a study by Voegeli (1952), an
intensity of light range of 20-215 foot-candles did not affect the rate
of color change of unwrapped samples under proper storage temperature.

In cases where light increased storage temperature, there was a prapor-
tionate discoloration.

Kampschmidt (1955) reported that wavelength is one of the most im-
portant factors causing fading, particularly in cured meat products.
Townsend (1958), by use of color filters, indicated that the wavelengths
of light between 560 and 630 mu (yellow and orange portion of the Spec-
trum) are responsible for the degradation of the color of prepackaged
frozen meat. Also, those steaks stored under green and purple filters

showed the least amount of metmyoglobin formation.

6. Effect of bacteria
According to Robach (1955), the addition of cell suspensions
of aerobic bacteria to steaks greatly increased the rate of discoloration.
Sparsely populated suspensions produced a more rapid appearance of metmyo-
globin than did high cell concentrations, which created reducing conditions
forming the purple color of myoglobin. The visible changes in color were
found to be associated with the oxygen demand of the surface tissue in-

cluding the demand of possible contaminating microorganisms. Inhibitors

-13-

of respiratory activity slow the rate of metmyoglobin formation. Thus,
it was concluded that the primary role of bacteria in meat discoloration
is in the reduction of the oxygen tension in the surface tissue. Neill
(1925) reported that pneumococci cause reduction of metmyoglobin to myo-
globin under exclusion of molecular oxygen. Upon the introduction of
small amounts of molecular oxygen, the reverse reaction was demonstrated

due to the production of peroxides.

7. Effect of enzymes

Grant (1955) reported that oxidative changes of myoglobin were
intimately related to the functioning of enzyme systems related to oxygen.
He stated that succinic dehydrogenase, alpha glycerophosphate dehyrogenase
and cytochrome oxidase have appreciable activity in beef. Brown and Tappel
(1958) reported that in the interior of fresh meat, respiratory enzymes
such as succinoxidase consume oxygen and tend to deoxygenate oxymyoglobin
to the reduced form. Lawrie (1953) demonstrated that the succinic dehy-
drogenase-cytochrome system catalyzes intracellular oxygen uptake and he
found a correlation between percent myoglobin and activity of cytochrome

oxidase.

Color Measurements as an Analytical Tool

The science of color is a complex and broad field and according to
Webster may be defined as a "sensation evoked as a response to the stimu-
lation of the eye and its attached nervous mechanisms by radiant energy
of certain wave-lengths and intensities." Livingston (1959) has explained
the broad ramifications and developments of color analysis. Color defin-

ition may be utilized in food inspection as a criteria on quality of raw

material, which must satisfy Specifications of the U.S.D.A. For example,

-14-

under undesirable storage, color variations may be detected before flavor
alterations. As an analytical tool, calorimetry enables the food chemist
to perform quantitative analysis on numerous food constituents such as
vitamins, minerals, and pesticides. Although the human eye can frequently
be employed in color appraisal, there are many variables introduced in-
cluding departures from normal vision, lighting, sample presentation,
observer fatigue, and acuity of color memory.

In order to standardize color analysis many instruments have been
adapted to the food industry (Livingston, 1959). Important techniques
of color analysis are comparators such as the Wesson Tintometer using
mixtures of oil colors to match a sample and the Lovibond Tintometer
applying the addition and subtraction of filters from a white light source
in order to obtain a match. The Ridgeway Charts and the Maery and Paul
Dictionary of Color may also be employed as a comparative technique in
the identification. A major advance in color analysis was the develOp-
ment of a photoelectric calorimeter, which replaces an observer with a
photoelectric cell. The spectrOphotometer was then developed, which
measures light of a particular wave-length by use of a prism and can be
used to characterize a food component by means of an absorption curve.
In addition to methods utilizing transmission of light, there are many

other colorimetric techniques based an emission and flouresence.

1. Munsell Disk Calorimetry
Munsell disk calorimetry has been established on the basis that

color is composed of three dimensions: hue, value, and chroma (Nickerson,

-15-

1946). Hue may be defined as the quality by which one may distinguish

one color from another such as red from green. Value is defined as the
relative lightness and darkness of the color. Chroma is the strength or
intensity of the color. The Munsell system may be pictured in the form

of a sphere whose circumference is composed of ten major hues which radi-
ate out like spokes on a wheel from a vertical scale. The hues include
red, yellow-red, yellow, green-yellow, green, blue-green, blue, purple-
blue, purple, and purple-red. Each division is subdivided into ten steps
for accurately matching a given color that does not fall exactly on a major
division. Value is the vertical axis consisting of a scale extending from
black (0) at the bottom to white (10) at the top with a range of nine in-
termediate greys. The chroma scale is horizontal and extends from a grey
on the vertical axis outward. The chroma of red has the greatest range

of intensity. By employing the spinning disk which contains adjustable
proportions of the achromic colors (black and white) and chromic colors
(red and yellow), a color can be notated in terms of hue, value, and chro-
ma. The percentage of colors used are determined by matching the disk,
which is rotated at constant speed by a motor, with the sample by observa-
tion through an eye piece. After obtaining the match, the perca1tage of
each color is converted into the tristimulus criteria X, Y, and Z, tabu-

lated, and finally converted into Munsell renotations by use of graphs.

2. : Gardner Color and Color Difference Meter
The ' . Gardner Color and Color Difference Meter is an instru-

ment employing reflectance of light and consists of an exposure unit and

-l6-

a measuring unit (Instruction Manual Gardner Laboratory, Inc.). The ex-
posure unit consists of a light source, mounting for specimens, and means
of viewing the Specimens with photocells. Two light beams from a single
source are directed along separate paths to two photo cells. One beam of
light is divided into sections which strike the sample at 45° angle of
incidence. The light is diffused perpendicularly from the sample and
passes through a fluted lens onto a photocell. There is also another
photocell called a standard against which the sample is compared by means
of the other beam of light. The standard is based on reflectance from
magnesium oxide, a nearly perfect white which has 98% reflectance. The
current generated by the photocell containing the sample is conducted to
the measuring unit where various current levels from the standard photo-
cell are measured against it. Thus, two photocells operate together in
each reflectance measurement so that temperature effects will be balanced.
The measuring unit consists of potentiometer rheostats, switches,
and recording values of photocell current on scales proportional to the
color. The reflected light from the exposure unit impinges on the photo-
cells and creates a current proportional to its intensity. The Signal is
then transmitted to the measuring unit, where three motor driven potentio-
meters called helipots balance the signal generated by the two photocells.
Duodials mounted on the front panel are directly coupled to the helipots,
and the readings obtained from them give the colorimetric specification
of the sample. Thus, test currents obtained from the exposure unit are

measured with three potentiometer rheostats relative to current obtained

-17-

from a constantly illuminated comparison photocell.

The Color Difference Meter presents three dials for each color mea-
sured, including numbers for L, aL, and bL. The L scale is indicative
of the relative lightness and darkness of the sample and corresponds with
value in the Munsell system. A sample which appears about halfway be-
tween black and white will have a reading of 50. The other two readings
are aL and bL, which are defined in terms of the tristimulus criteria X,
Y, and Z and are rectangular coordinates of chromaticity in any place in-
tersecting the color solid perpendicular to the black and white axis.
Both aL and bL may be either positive or negative. The aL scale measures
redness and greenness, which are complementary colors. The bL scale mea-
sures yellowness and blueness, which are also complimentary colors. For
the evaluation of meat color the aL scale is set positive to measure red-
ness and the bL scale is also set positive to measure yellowness. In the
illustration below, both the Munsell and reflectance color solids are

represented.

3. Spectrophotometry
A third method applied to analysis of color is spectrOphotametry
(Beckman Instruction Manual). This method is based on the diffraction of
white light by a prism, which is passed through a narrow slit onto a grat-
ing and then through a photocell containing the solution to be measured.
This causes a current change in the galvanometer proportional to the trans-
mittancy of the solution. When the desired absorption band is located,

the instrument can be set for this wave-length and the concentration of

-13-

The Munsell and Reflectance Color Solids

 

 

 

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Three dimensional color scale defining hue, value, chroma. Munsell Color

Co., Inc. Reprint Munsell Book of Color, page 1

whfie : I007; Reflectance

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Three dimensional color scale defining L, aL, bL' Gardner Laboratory,

Inc. Reprint Industrial Quality Control (Vol. 17, page 3, 1960).

-19-

absorbing material determined on the basis of the percent transmission.
In order to determine concentration, the Law of Lambert and Beer is em-
ployed, which states that the absorbsnce or aptical density is equal to
the product of extinction coefficient, photocell length in cm, and con-
centration. A complete outline for the determination of myoglobin is
presented in the procedure. In addition to the determination of concen-
tration of a chromophoric component, the SpectrOphotometer may be used

as an indication of purity by plotting wave-length against absorption.

EXPERIMENTAL PROCEDURE

Source of Meat
Pork and beef were obtained from Michigan State University Meat

Laboratory and lamb from a local meat distributor.

Sampling Procedure

The longissimus dorsi muscle was removed from the beef rib, pork
loin, and lamb rack and trimmed of most external fat. Color measurements
for each muscle were completed within five days. Ten pork loins were
sampled in triplicate. Five replications from each of five beef ribs
were studied. For lamb, triplicate samples of five single racks were
employed. All meat was stored and studied within a temperature variance
of 30-36°F, relative humidity of 75-85%, and air movement of 15-20 feet

per minute.

Color Measurements

Surface color of pork, beef, and lamb was determined by Munsell color-
imetry and by the 7 . Gardner Color and Color Difference Meter. Oxy-
genation was allowed to progress in total darkness except for when color
measurements were made. A spectrOphotometric estimation of myoglobin was
also performed on lamb.

1. Munsell Disk Calorimetry

The Munsell spinning disk evaluation was employed at periodic

time intervals and renotated on the basis of hue, value, and chroma. A

-20-

-21-

prepared sample was mounted upon a fitted wooden support before placing
on the stand. Thus, a sample was easily removed and replaced while still
observing the same region for the successive readings. Voegeli (1952)
demonstrated that different areas of a muscle will result in different
renotations depending upon the concentration of intramuscular fat and
myoglobin concentration of the region. The sample was adjusted so that
the top surface was at the same level as the disks, allowing equal view-
ing areas. This area was about two cm2 at about 8 3/4 inches from the
Optical eye piece base. In evaluating the color of the sample, such fac-
tors as the red-yellow relationship, lightness and darkness, and intensity
of the color were considered. Since experience was required for the ad-
justments of disk combinations, practice trials were conducted on pork,
beef, and lamb until satisfactory proficiency was obtained. Although
there was a need for as accurate and rapid matches as possible, an exact
‘match could not be made in all cases. For example, the addition of one
unit of yellow would change the disk mixture from Slightly deficient in
yellow to excessive yellow. In such cases, the lesser units of yellow
were taken for renotation. Upon obtaining a satisfactory match of the
sample, the percentage areas of the disk mixture were recorded. By know-
ing the International Commission on Illumination (I.C.I.) tristimulus
values (X, Y, Z) of the individual disks and the number of units used in
the match, the Munsell renotation was calculated. The tristimulus values
for color were obtained as a weighted percentage of each disk used with
the weights being proportional to the disk area (Nickerson, 1958). The

following disks were employed.

-22-

Specifications for Disks used in Munsell Calorimetry

 

 

 

 

Lamb and Beef Pork
Color Renotation Prod. # Color Renotation Prod.#
Red 5R 4/14 3987 Brown 8YR 6.4/11.2 884
Yellow 5Y 8/12 4848 Red 5R 4/14 3987
Black N1 4174 Black N1 4174
White N8 4757 White N8 4757

 

Since a rate study on oxygenation of pork, beef, and lamb was con-
ducted, a series of readings were taken. The procedure involved an ini-
tial observation on a cross section of the muscle followed by readings at
fifteen minute intervals for two hours on pork and lamb and for three
hours on beef. Maximun oxygenation was considered as the color evalua-
tion at twenty-four hours.

In order to express color differences in terms of a single number
rather than as hue, value, and chroma, a standard color was determined.
This involved the direct oxygenation of longissimus dorsi cross-sections
of pork, beef, and lamb in a chamber, which was evacuated and filled with
pure oxygen. An exposure of two hours in darkness at 32°F was taken as
the standard with which air oxygenated samples were compared. The follow-

ing standards were used:

Standards
*Beef 7.0R 4.0/8.0
Lamb 8.4R 3.8/6.5
Park 2.4YR 4.8/5.3

*Established by M. M. Voegeli Ph.D. thesis M.S.U. 1952

-23-

After determining the standards, the Index of Fading formula (Nick-
erson, 1946) was employed for the determination of color change in terms
of a single number. The formula is as follows:

I §(2AH) + 60V+ 3110

I Index of Fading

C = Chroma of the sample

H = Difference in hue between sample and standard
V = Difference in value between.sample and standard
C = Difference in chroma between sample and standard

A plot of Indexes at each time interval was then made to determine the

rate of oxygenation.

2. Gardner Color and Color Difference Meter

Surface color changes were also studied by the Gardner
Meter which records an L value, aL, and bL which correSpond to lightness,
redness, and yellowness. Readings were taken at the same time intervals
described for Munsell calorimetry. The cross sections of samples were
placed on a glass plate (4 x 3 x 1/8 in.) which in turn was placed over
an aperture of 15/16 inches with a "large" setting on the ' Gardner
Meter. Before reading the samples, the machine was conditioned for at
least one-half hour to the following reference plates. The machine was
continuously standardized against the reference plate for each sample at

each time interval.

-24-

 

 

Reference Plates for Gardner Meter

Beef and Lamb Pork
L 24.1 53.8
aL 27.4 27.3
bL 12.5 8.5

 

The differences of the color of each sample at each time interval from
the above reference plate were recorded. The color changes in pork, beef,
and lamb due to oxygenation were thus traced by the differences in the L,
aL, and bL of the Sample from the L, aL , and bL of the reference plate.

The changes in color were appraised by aL/bL ratio, total color differ-

 

ence from the standard as expressed by\fih L2 + lgaLZ +-[Xb£2 , or by in-

creases in aL (redness).

3. Spectrophotometry

A third method employed only for lamb was the total myoglobin
present according to a spectrophotometric procedure outlined by Ginger
gtflg1. (1954) and modified by Henry (1959). The procedure used was as
follows. Duplicate 25 gram aliquots of ground sample were minced in a
Waring blendor for two minutes with 100 ml of cold distilled water and
centrifuged for 20 minutes at 2500 rpm at a temperature of 34°F. The
supernatant was filtered through cotton, which retained muCh of the fat
that had risen to the tap of the solution, and adjusted to pH 7.0 with

1 N NaOH. Foreign proteins were precipitated by addition of 25 volumes

-25-

of saturated basic (pH 8) lead acetate based on volume after neutraliza-
tion. This was added at room temperature Since at lower temperatures
the protein precipitation is incomplete while at high temperatures (38°C)
the myoglobin will also precipitate (Schweigert, 1954). The precipitated
solution was allowed to stand for twenty minutes and was then centrifuged
for 20 minutes at 2500 rpm. The resulting supernatant was brought to pH
6.6 and the phosphate to 3 M by the addition of solid mono and dibasic
potassium phosphate in the ratio of 2.32 males to .68 moles, which preci-
pitates hemoglobin and leaves myoglobin in solution. After the third
centrifugation of twenty-minutes, the supernatant was filtered through
Whatman number 41 H filter paper into a 50 m1 volumetric flask. After
removing two ml of the solution, potassium ferricyanide CK3Fe (CN)6)waS
addedfat .6'millimoles per liter followed by sodium cyanide at .8 m M/l.
Care was taken to insure complete dispersal of each cyanide treatment
because the potassium ferricyanide oxidizes all of the myoglobin into
metmyoglobin andsodium cyanide reacts with metmyoglobin to form the
cyanoderivative, cyanmetmyoglobin. This provided a relatively stable
solution which was read at 540 millimicrons and slit width of .Ol-.02
millimeters on the Beckman DU spectrophotometer. The blank consisted of
the same reagents and concentrations as the sample.

For the purpose of calculations, the extinction coefficient of 11.5
was considered equivalent to that of cyanmetmyoglobin (Drabkin, 1935).
A molecular weight of 16,500 for myoglobin was also assumed (Ginger.g£
‘21., 1954). The following expression was used to convert concentration

of myoglobin to milligrams per gram of fresh tissue.

-26-

(A) Team (c) g; (E) 199 (C) ,9 =
(B) 11,500x (D) 25K (F) 80x09 48 9.33K

(A) = Molecular weight of myoglobin
(B) = Extinction coefficient
(C) = Initial 100 m1. H20 + 25 g. sample tissue
(D) = 25 grams of sample tissue
(E) = 80 ml. of supernatant + 20 ml. basic lead acetate
(F) = 80 m1. of supernatant
(G) - 48 m1. of supernatant + 2 ml. of cyanide solutions
(H) = 48 m1. of supernatant
(K) - constant
Using the above equation, the concentration of myoglobin in milligrams

per gram of tissue can be exPressed by the product of K and the optical

density reading.

Statistical Analysis

The statistical analysis of data included means, simple correlation
coefficients, and predicting formulae. The following formulae used in analy-
zing these data were obtained from Snedecor (1958).

Correlation coefficient

NSXY - (@9089. '
r " V[N€x2 - (s 102ij r1 - (SUE

Slope of regression line

B = NSXY - (S X)_({Y)
N2 X‘ - (8)z

-27-

"Y" intercept
A = Y - H i
Predicting formula

A
Y=A+B(X)

RESULTS AND DISCUSSION

The Effect of Oxygenation Measured by the Munsell Color System

Oxygenation appeared to exert two primary effects on the Munsell reno-
tation. Hue progressed from the yellow-red region toward the red region as
oxygenation increased; Chroma increased in magnitude with reSpect to oxy-
genation. Value, during a twentyofour hour period, remained relatively
constant. For example, the following changes were observed in park. Maxi-
mum hue changed 1.5 units from 7.1 YR to 5.6 YR.in ninety minutes while
maximum chroma increased 1.1 units from 2.5 to 3.6 in twenty-four hours.
Thus, hue changed relatively rapidly in ninety minutes and then remained
constant, while chroma increased more gradually and changed slightly less
than hue. Value remained constant at 5.6. Data for beef indicated Similar
trends. Hue increased in redness by changing 1.7 units from 2.1 YR to .4
YR.while chroma increased 2.6 units from 3.4 to 6.0 in twenty-four hours.
Both hue and chroma changed gradually with reSpect to increasing time of
air exposure but chroma changes were far greater than hue. Value remained
constant at 3.9. In lamb, hue changed 1.3 units from 2.3 YR to 1.0 YR while
chroma increased 2.1 units from 3.4 to 5.5 in twenty-four hoursmfis with beef,
both hue and chroma changes were gradual but chroma “was greater. Value re-
mained constant at 3.9.

When the Munsell renotations were converted to Index of Fading by the
Nickerson Formula (1946), oxygenation decreased the Index of Fading propor-
tional to time of exposure to the air. Thus, as the Index of Fading decreased,

the renotation of the sample more closely approximated the renotation of the

-23-

-29-

standard which had been oxygenated with pure oxygen as described in the
procedure. In park, the Index of Fading decreased 3.9 units from 18.7
initially to 14.8 in ninety minutes, which was the time required for maxi-
mum oxygenation. For beef there was a decrease of 7.0 units from 22.4 to
15.4. Lamb decreased 5.4 units from 16.3 to 10.9. Therefore, the order
of extent of change in Munsell renotation based on Index of Fading due to
oxygenation appeared to be beef, lamb, and pork.

In Table l and Graph 1 the data obtained are summarized. Means of
renotations are based on thirty samples for park, twenty-five for beef,

and fifteen for lamb.

The Effect of Oxygenation as Measured by Reflectance

The . h . Gardner Color and Color Difference Meter was employed to
determine change in surface color due to oxygenation using the L, aL, and
bL scales. As With the Munsell system, oxygenation affected two criteria
of color. As oxygenation increased, the aL readings, corresponding to red-
ness, increased extensively. The bL readings, correSponding to yellowness,
also increased but to a smaller extent. The L data, indicative of value,
remained relatively constant. Most of the change in both aL and bL occurred
in the first thirty minutes. Changes in color of a sample were determined
by standardizing the color difference meter with standard plates and mea-
suring the difference between the sample and the plate in terms of L, aL,
and bL. The standard pork plate had the specifications of L.= 68.5, aL =
17.4, and bL = 7.5, while beef and lamb were standardized to L = 24.1,

aL a 27.5, and bL = 12.5.

-30-

 

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-32-

In pork an increase was observed on the 3L scale of 2.9 units from
5.9 to 8.8 while on the bL scale there was only 2.1 units increase from
8.1 to 10.2 for twenty-four hours. In thirty minutes there was an increase_
of 1.3 units in aL and 1.2 units in bL. The L scale remained relatively
constant with a slight downward trend from 42.4 to 40.5. The most exten-
sive changes occurred in beef. The aL increased 7.3 units from 14.1 to
21.4 while the bL increased 1.8 units from 9.4 to 11.2. Of these changes,
4.3 units of aL and 1.5 units of bL resulted during the first thirty min-
utes. The L scale declined slightly from 25.2 to 24.8 in three hours.
Similar but less extensive changes developed in lamb. The aL scale increased
5.0 units from 14.2 to 19.2 while the bL changed 2.1 units from 9.3 to 11.4.
In thirty minutes there was an increase of 3.1 units in aL and 1.6 units
in bL. The L scale remained constant at 25.0 to 25.5.

There are three methods for appraising rate of color change by the

Color Difference Meter. These included tracing the change in aL, total

 

light difference expressed by the relationship AEZ = \Asz + A 3L2 + [J bLZ,
and the aL/bL ratio. Changes in aL were previously stated to increase
with oxygenation. Total light difference decreased as oxygenation increased.

It is also important to note that if the percent changes of aL and

 

\/z:\ L2 + A 3L2 + A bL2 are compared, there will be an agreement within 5%.
Changes in total light difference in park were too small to be established.
In beef there was a totaybhange of 7.4 units from 13.7 down to 6.28 in

twenty-four hours. In thirty minutes there was a change of 4.5 units. In

lamb a similar decrease was oflserved. A drop of 5.1 units from 13.6 to

-33-

8.49 was noted in twenty-four hours with 3.3 units decrease resulting in
thirty minutes.

A third technique used to evaluate color change is the aL/bL ratio
which will increase with oxygenation because aL or redness increased more
rapidly than bL, or yellowness. However, changes in aL/bL were small when
compared to aL and total light difference. In pork an increase of .155
units from .728 to .863 was observed in twenty-four hours. In thirty
minutes there was .046 units increase. Beef indicated an increase of .41
units from 1.50 to 1.91 in twenty-four hours. In thirty minutes there was
a .19 unit change. Lamb developed an increase of .15 units from 1.53 to
1.68 with .06 units change occurring in thirty minutes. Little correSpon-
dence was found in percent color change between aL/bL and total light
difference or aL. All information obtained from the Color Difference

Meter is summarized in Tables 2 to 4 and Graph 2.

Percent Change in Color Due to Oxygenation

Two methods have been applied for the detenmination of rate of bloom-
ing or increasing redness of muscle pigment due to oxygenation. Although
there is some lack of agreement between data obtained from Munsell Colori-
metry and the ' I Gardner Color and Color Difference Meter, it can
generally be concluded that blooming is most extensive and rapid in the
first hour for pork, beef, and lamb. In this study, maximum bloom was
assumed to be the color Specifications obtained by each method after twenty-
four hours of exposure to the air in darkness and sealed in a plastic bag

to limit moisture loss. The percentage color change was derived in the

-34-

 

 

 

 

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-33-

Munsell system by calculating the Index of Fading from the Nickerson
Formula and dividing the difference in index at each time interval from the
initial index by the total change in index. Similarly, the percent change
in theGardner system.was determined by dividing the difference in aL at
each time interval from the initial aL by the total change in aL.

In park there was a change of 87% by Index of Fading and 55% by aL
in one hour. Munsell calorimetry indicated that a 100% change due to
blooming occurred in ninety minutes while reflectance inferred that bloom-
ing is much more gradual during a twenty-four hour period. Data from'beef
also demonstrated that blooming occurred most rapidly during the first
hour as shown by 45% change in Index of Fading and 74% in aL. Both methods
agree that at least 90% of the change was produced in three hours. Re-
flectance data indicated the rate of change in color to be much more rapid
than did Munsell calorimetry for beef. In pork Munsell calorimetry indi-
cated a much more rapid change than reflectance. Trends in data for lamb
were Similar to that of beef. Reflectance measurements showed that there
was a more rapid change than did Munsell calorimetry. The percent change
in one hour was 78% by aL as compared to 67% by Index of Fading. Both
methods agree that over 85% of the total change resulted in two hours.
A conclusion that may be determined from the obtained data is that muscle
tissue containing small concentrations of myoglobin required less time
to become fully oxygenated than did tissue having higher myoglobin con-
tent. Thus pork, lamb, and beef appeared to be the order of least time

required to achieve maximum bloom. This is substantiated bijunsell

-39-

colorimetry as shown by reSpective changes of 87%, 67%, and 45% change
in Index of Fading in one hour. Reflectance data showed less conclusive
change in percent aL. In Table 5 and Graphs 3 and 4 the percent color
changes for park, lamb, and beef are summarized using the same sampling
as described in Munsell calorimetry.

Table 5. Comparison of percent color change between Munsell and reflect-
ance systems

 

 

 

 

Index of Fading 8L,

Time Pork % Lamb % Beef % Pork % Lamb % Beef %
o -- -- -- -- -- --
15 36 9 9 34 44 42
30 56 39 24 45 62 59
45 74 53 34 52 72 67
60 87 67 45 55 78 74
75 92 78 59 62 80 77
90 100 85 64 62 80 84
105 98 91 70 62 84 88
120 98 95 74 62 86 88
150 100 -- 85 76 -- 93
180 -- -- 90 -- -- 96
24 hrs. -- -- -- -- -- --

 

On the basis of the above data, recommendations can be made for ap-
timal time to read color as a prediction of final color based on percent

change in a reasonable time lapse. The following conclusions were drawn:

 

 

 

 

 

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-42-

1. Park can be read in thirty minutes by Munsell colorimetry'which
will produce a 56% change.

2. Park can be read in forty-five minutes by reflectance which will
produce a 52% change.

3. Beef can be read in seventy-five minutes by Munsell calorimetry
which will produce a 59% change.

4. Beef can be read in thirty minutes by reflectance which will
produce a 59% change.

5. Lamb can be read in forty-five minutes by Munsell calorimetry
which will produce a 53% change.

6. Lamb can be read in thirty minutes by reflectance which will

produce a 62% change.

Conversion of Reflectance Data to Munsell Renotations

The Munsell renotation may be determined indirectly by two different
methods from data obtained from.the Color Difference Meter. One method
involves the conversion of GardnerL, aL, and bL into 1.0.1. tristimulus
values (X, Y, Z) by appropriate conversion calculations and using the
same I.C.I. chromaticity diagrams employed for Munsell renotations (Davis
and Gould, 1955). The second technique employs the conversion of Gardner
L into Munsell value and uses diagrams which directly convert aL and bL
into hue and chroma (Davis and Gould, 1955).

The first method requires the computation of the tristimulus values
(X, Y, Z) from Gardner data L, aL, and bL by means of the following equa-

tions. Initially, Y is determined.

x”

if“ (. __
r; fl { E. V—‘H'V

   

 

-43-

L = 100 (yl/Z) or Y - (IUUDZ

aL - 175 (1.02 x -+y)
yl/2

yl/Z

Knowing Y and aL, X is calculated and knowing Y and bL, Z is calculated.
The chromaticity coordinates (x, y, z) are computed from the tristimulus
values (X, Y, Z) as fractions of their totals as follows. The sum of x,

y and 2 must equal one.

X Z
=———-————— a Y =——-————
X+Y+Z’y X'TYTZ’Z X+Y+Z

In order to determine Munsell value, the I.C.I. (Y) equivalents published

X

by Nickerson (1948) must be consulted. Because data are presented in terms
of Yv (%) relative to a standard white magnesium oxide, the Yu' (%) must
be divided by 100 to obtain Y from which any specified Munsell value can
be determined. Knowing value, x, and y, the Munsell renotation for hue
and chroma can be observed from the I.C.I. chromaticity diagrams in the
usual manner. In cases where the sample value lies between two values,
the usual interpolations must be performed.

The second method involves the direct conversion of Gardner-L, aL, and
bL readings into'MMnsell renotations. First, L readings are converted to
Y by the Gardner equation Y = ($1332. The number obtained for Y is converted
to Ytt (%) by multiplying by 100. The correct Munsell value is then obtained
from the Nickerson tables. After L is converted to value, the Munsell value
is used to determine which chromaticity diagrams to use in order to obtain
hue and chroma renotations from Gardner aL and bL readings. In order to

facilitate conversion, the hue and chroma renotations of any point which

-44-

falls within the boundaries of an area established by two hue and two
chroma loci are further geometrically subdivided into .5 hue units and .5
chroma units. The Spacing of hue and chroma steps is less uniform in
terms of 3L and bL than in terms of the Munsell units because of the con-
figuration of the color solid (Younkin, 1950). If the value obtained
lies between two values, the hue and chroma renotations from the two ap-
proPriate diagrams must be interpolated as in the Munsell system. De-
tailed conversions and diagrams are presented by Davis and Gould (1955).
MacGillivray (1931) reported a comparison of data obtained by direct
renotation of Munsell hue, value, and chroma with data derived from re-
flectance L, aL, and bL based on tomato color. His conclusions were:
1. ‘Munsell hues obtained directly were considerably more red than
hues calculated fram Gardner readings.
2. ‘Munsell chromas obtained directly were considerably higher than
chromas calculated from Gardner readings.
3. Munsell values were approximately the same as values calculated
from Gardner readings.
The above statements were based on nominal Munsell notations before the
”Study of Spacing of the Munsell system was made by a subcommittee of the
calorimetry committee of the Optical Society of America." (Davis and
Gould, 1955). Now more precise charts and tables are available constitu-
ting the definition of the Munsell system in smoothed I.C.I. chromaticity
diagrams. In addition to Spacing of charts, Gould (1955) has reported
several other factors which will effect renotation conversion. Instrumen-

tal illuminating conditions in the Color Difference Meter effect the L,

-45-

aL, and bL obtained, which effect the conversion. Also, different read-
ings will result from small and large aperture size. Large area illumin-
ation Spreads the light from the light source over the entire aperture in
a relatively diffuse manner. Small area illumination concentrates the
light in a small Spot allowing greater possibility of light loss due to
lateral dispersion. There is also the chance of obtaining readings in
localized areas which are not representative of the whole by use of the
small aperture.

According to data obtained on beef and lamb, results appeared to be
directly apposite to MacGillivray (1931). The following trends were ob-
served in data derived directly from renotation of Munsell hue, value,
and chroma in comparison to conversion from reflectance L, aL, and bL
using the large aperture and constant illumination.

1. Munsell hues were more yellow-red or less red than converted

hues from Gar/dner readings.

2. Munsell chromas were lower than chromas obtained from conversion

of Gardner readings.

3. ZMunsell value units were higher, or whiter, than value converted

from ‘Gradner readings.

4. Index of Fading approximately correSponded between the two

methods when based on the same standard index of fading.

Since all samples were viewed by the photocell through a glass plate
described in the procedure, an attempt was made to calibrate the error
caused by the glass plate. This was done by standardizing the machine
with the reference plate L = 24.1, 3L = 27.4, and bL - 12.5. The glass

plate was then placed over the aperture and the reference plate placed

-46-

on tap of the glass. The mean of readings taken through the glass were
L - 21.9, aL - 21.9, and bL = 11.1. The effect of the glass was to de-
crease L by 2.2 units which corresponds to a dr0p of .3 value units when
converted to the Munsell system. There was also a drOp of 5.5 aL units
and 1.4 bL units due to the glass. This caused an approximate loss in
redness of .4 R units hue, and a decrease of 1.6 units chroma when con-
verted an a value diagram of 3. Thus the effect of the glass was to
decrease L, aL, and bL readings which decreased value, redness, and chro-
ma. Therefore, the glass accounted for much of the difference established
in the data between the Munsell renotations derived directly by disk
calorimetry and by conversion from reflectance.

An attempt was made to convert reflectance readings in park to the
Munsell system but changes were considered too small. In Tables 6 and 7
the results obtained for beef and lamb are summarized for the conversion
of reflectance data to the Munsell Color System using the second method
of conversion.

In Table 6 the changes in beef color due to oxygenation were record-
ed for both the original Munsell renotation obtained by disk calorimetry
and converted Munsell renotation derived by the Color Difference Meter.
Comparative Indexes of Fading and percent color changes based on Indexes
of Fading are also presented. Initially the original Munsell renotation
was 2.1 YR 3.9/3.4 as compared to 1.1 YR 5.0/4.7 for the converted reno-
tation. Thus, the original renotation was found to be more yellow-red or
less red in hue, higher in value, or whiter, and lower in chroma or less

intense than the converted renotation. Both renotations were converted

-47-

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an we m.oH N.o\o.m MM mm. ma N.mH o.¢\m.m MM m.H Co
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aumn ooamuooamon mauso>aoo mumn Masada: Hmaflwwuo

 

band you ooamuooamon Baum aowmuo>aoo MA was Mauoouwv monwauoo some Hamma:z_mo Managua .N manna

-49-

to Index of Fading using the same reference index which resulted in approx-
imately“ the same index at each time interval for the two methods. For
example, initially the original index was 22.4 while the converted index
was 23.6. The percent color changes were also compared and indicated

that from ninety minutes to three hours there was an agreement of within
13%. For example, in ninety minutes the original Munsell data indicated

a 64% change while the converted L, aL, and bL data showed a 77% change
based on percent change of Index of Fading. The percent change in aL was
84%.

In Table 7 the results for lamb are summarized, which were found to
closely parallel those for beef.Again, the original renotation for hue
was more yellow-red, value was higher, and chroma was lower than the con-
verted renotation. For example, the original initial renotation was
2.3 YR 3.9/3.4 while the converted renotation was 1.0 YR 3.0/4.7. As
with beef, close correSpondence was obtained between Indexes of Fading as
shown by 16.3 for the original Munsell renotation as compared to 15.1 for
the converted L, aL, and bL renotation based on the same standard Index
of Fading. Close correSpondence was also obtained within 12% for the
percent change of color between the methods. For example, the original
percent change in one hour was 67% as compared to 74% by the converted

method. The correSponding percent change in aL was 78%.

Correlation Between Methods of Color Analysis
1. Correlation between reflectance and Munsell systems.
Rikert (1956) indicated that it is desirable to express color

as a single number and conducted a survey to determine whether meat color

-50-

on the Gardnermeter correlated significantly with Munsell renotation.
Since value in the Munsell system is practically indentical to L in the
Qfinémr system, he attempted no correlations on value. He found that aL
showed a highly significant correlation with both hue and chroma on

fresh ground meat. Also, bL showed a significant correlation only with
chroma. Since 3L significantly correlated with hue and chroma, he stated
that it seems to qualify as a satisfactory index of the color of fresh
meat.

Using data obtained from the Munsell and Gardner systems, correlations
were determined between Index of Fading and aL in pork, beef, and lamb.
Highly significant negative correlations were obtained by comparing the
Index of Fading and aL at each time interval during the oxygenation study.
A correlation of -.881 was found for park based an eleven time intervals.
A correlation of -.922 was found for beef based on twelve time intervals.
A correlation of -.922 was found for lamb based on ten time intervals.
Thus, there is a highly significant negative correlation between Index of
Fading of the Munsell system and aL of the Gardner system. In Table 8 and

Graphs 5 to 7, the information on correlation is summarized.

Table 8. Correlation of Munsell and reflectance data

 

 

Pork Beef Lamb
Correlation
coefficient -.881 -.922 -.922
Slope (B) -1.540 -l.009 -1.247
"Y" intercept (A) 27.30 38.13 . 34.95
Predicting formula Y=27.3-1.54(X) Y=38.l-1.01(X) Y=34.9-l.25(X)

Level of signifi-
cance 1% 1% 1%

 

 

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-54-

2. Correlation between Munsell and spectrophotometric calorimetry
Same attempts have been made to correlate the Munsell and spec-

trophotometric methods of analysis. Butler (1953) studied relation be-
tween Index of Fading and percent metmyoglobin in fresh beef and found
the correlation coefficients ranged from .830 to .882. Townsend (1958)
found a correlation on frozen beef of .777 to .930 between Index of
Fading and percent metmyoglobin. Henry (1959) found a correlation coeffi-
cient of .69 on pork between Index of Fading and total myoglobin. In
limited research conducted on lamb, the results of the present study
indicate a non significant correlation of .596 between Index of Fading
and total myoglobin. This study was based on five trials comparing the
total myoglobin by the Ginger (1954) procedure as modified by Henry (1959)
with the Index of Fading obtained from different lamb samples at the
initial reading. A correlation of .604 was obtained between initial aL

in reflectance and total myoglobin on lamb an the basis of five trials.

Advantages and Limitations to Methods of Color Analysis

There are many advantages and limitations in the Munsell system of
calorimetry. Advantages include simplicity of apparatus, no effect from
electrical power fluctuations, inexpensiveness of apparatus, no sample
preparation, and the evaluation of surface color. Disadvantages include
human judgment in matching the disks with the sample, disagreement between
Operators on what is a match, length of time required to match while sam-
ple color is changing, alteration of color on disks due to air exPosure
and use, inability to replace disks with exactly the same color Specifi-

cation, aperator fatigue, operator training, and labor and time needed

 

 

-55-

to renotate.

The ' Gardner Color and Color Difference Meter also has many
advantages and limitations. Advantages include quick and precise measure-
ments, no Operator fatigue, impartial objective basis for judgment in
"borderline diSputes", small sample preparation, and no aperator training.
Limitations involve increase in error as Specification of color in sample
differs from the reference plate, "Metameric colors" or the same color
yielding different color data on the same instrument, some variance between
instruments, electrical fluctuations in the power line serving the poten-
tiometer, dependence on a complicated apparatus that may be difficult to
service, and error due to the reflection of glass on tap of which the
sample is placed for readings. According to the Gardner Laboratory ser-
vice bulletin (G6550), instrumental precision is comparable to the small-
est perceptible color difference discernible by the trained eye of a human
color matcher. This is usually considered to be about .2 - .3 NBS (Nation-
al Bureau of Standards Uhits). This service bulletin also stated that
the same reference plate will have a variance of .3 NBS units between
instruments.

A third method of color analysis applied only to lamb was Spectr0pho-
tametry. Advantages for Spectrophotometry include the elimination of
human judgment error, sample homogeneity, and an estimation of the rela-
tive percentages of reduced, oxy-, and metmyoglobin involved in meat
color. Disadvantages are labor required for sample preparation, greater
.possibility for procedure variance, and incomplete fractionation of myo-

globin during isolation.

SUMMARY AND CONCLUSIONS

A study was conducted to determine the oxygenation rates of pork,
beef, and lamb by the Munsell Calorimetry and the ' Gardner Color
and Color Difference Meter. On the basis of data obtained, recommendations
can be made for the time required to read color after one half of the color
change has occurred due to oxygenation. By Munsell Calorimetry, pork may
.be read in thirty minutes, beef in seventy-five minutes, and lamb in
forty-five minutes. By reflectance, pork may be read in forty-five‘min-
utes, beef in thirty minutes, and lamb in thirty minutes.

The effect of oxygenation on the methods of color analysis was also
reviewed. In the Munsell system, oxygenation appeared to increase the red-
ness of hue and to increase chroma while value remained constant. In the
Gardnersystem, oxygenation appeared to extensively increase 3L which car-
hresponds to redness. Also, bL, corresponding to yellowness, was increased
to a lesser degree. The L readings indicative of value, remained constant.
An attempt was also made to convert the Gardner system into the Munsell sys-
tem. Original Munsell renotations appeared to be more yellow-red, or less
red in hue, higher in value, or whiter, and lower in chroma than the con-
verted Gardner renotations. Indexes of Fading between the two methods
seemed to correspond very closely.

Several highly valuable relationships were found between Munsell and
reflectance calorimetry. In reflectance, aL was shown to compare closely
with total light difference on a percent color change basis. Thus, the

use of aL as an indication of color change eliminates the labor involved

-56-

 

 

-57-

 

_in calculating \fA L2 + AaL2 + AbLz. Also, a highly significant nega-
tive correlation was found between Index of Fading in the Munsell system
and aL in the Gardner system. Therefore, aL could be used as an indication

of rate of oxygenation.

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Beckman Instruction Manual 305A. 1957. Scientific Instruments Division,
Fullerton, California.

Bray, R. W., Rupnow, E. H., Hanning, F. M}, Allen, N. N. and Niedermeier,
R. P. 1957. Effect of feeding methods on veal production and
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Bowen, W. J. 1948. Notes on myoglobin preparation and iron content. J.

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Brooks, J. 1931. The oxidation of haemoglobin to methaemoglobin by oxy-
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Brooks, J. 1948. The oxidation of haemoglobin to methaemoglobin by oxy-
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Eighth RES. Confo Of AoMoIoFo 61-650

 

 

-6l-

Shenk, J. H., Hall, J. L., and King, H. H. 1934. Spectrophotometric
characteristics of hemoglobin. 1. Beef blood and muscle hemoglobin.
J. Bio. Chem. 105: 741-752.

Snedecor, G. H. 1957. Statistical Methods. 5th ed. The Iowa State
College Press, Ames, Iowa.

Theorell, H. 1932. Kristallinisches Myoglobin. Biochem. 272:1-7.

Townsend, W. E. 1958. Effect of temperature, storage conditions and
light on the color of prepackaged frozen meat. Unpublished Ph.D.
Thesis, Michigan State University, East Lansing, Michigan.

Voegeli, Marvin M. 1952. The measurement of fresh beef muscle color
changes by disc calorimetry. Unpublished Ph.D. thesis, Michigan
State University, East Lansing, Mdchigan.

Younkin, S. G. 1950. Color measurement of tomato purees. Food Tech.
4:350.

 

 

 

APPENDIX

-62-

 

 

0.HH ¢.M\N.m MM 0.0 m.¢H w.m\0.m MM H.0 ¢.wa 0.M\N.0 MM w.m .mHM am

 

 

 

 

m.mH q.m\~.m MM «.0 m.¢H M.M\0.m MM H.0 m.ma m.m\~.0 MM 0.0 omM
o.MH N.m\N.m MM m.0 n.0H w.m\0.m MM H.0 N.mH m.M\N.0 MM N.m oma
o.mM N.m\N.m MM m.0 0.0H m.m\0.m MM.0.m a.NM n.M\N.0 MM m.m moH
M.NM w.m\N.m MM w.n 0.0M N.M\0.m MM 0.0 m.NM m.m\N.0 MM m.m om
m.MM N.m\M.m MM N.m H.0H N.m\0.m MM M.0 o.wH ¢.m\~.0 MM m.m mm
w.HH m.M\H.m MM N.m 0.0H a.M\0.m MM H.0 N.wM m.m\N.0 MM m.m O0
«.ma M.M\H.m MM m.0 0.0M N.M\0.m MM N.0 o.ma o.M\N.0 MM 0.0 00
¢.ma o.m\M.m MM m.0 0.0M o.M\0.m MM 0.0 m.mM o.m\~.0 MM «.0 on
0.0M m.N\H.m MM w.0 m.0M m.~\0.n MM 0.0 m.om m.m\m.0 MM 0.0 ma
0.0H ¢.N\N.m MM m.0 m.NH N.N\0.m MM m.N a.H~ n.N\N.0 MM o.N o
wawnmm aoHHMuoomM waaumm noaumuoaoM weavmm aoHuMuoaoM aEMH
mo MoncH mo ManaH mo MomsH
m oaeemm N oaaamm H oaeemm
M neon

 

MHuoEMHoMoo Manama: Mn manwmuno mumm Muam .H Mansona<

 

-63-

 

 

 

 

 

 

N.~M ~.¢\0.0 MM H.0 N.0H 0.0\0.0 MM N.0 H.0M 0.m\0.0 MM 0.0 .muc em

0.0M M.e\0.0 MM 0.0 0.0M 0.0\0.0 MM 0.0 0.0a m.0\0.0 MM 0.0 00M

0.0M H.¢\0.0 MM 0.0 0.0M 0.0\0.0 MM 0.0 0.0M a.m\0-0.MM «.0 00M

0.0M 0.0\0.0 MM 0.0 0.0- 0.m\m.0 MM 0.0 0.0M a.0\0.0 MM «.0 00M

0.0M 0.m\0.0 MM 0.0 0.0M 0.m\0.0 MM 0.0 0.0M ¢.0\0.0 MM 0.0 00

0.0M 0.m\0.0 MM 0.0 0.0M 0.0\m.0 MM 0.0 0.0M 0.m\0.0 MM 0.0 0N

0.0M 0.m\0.0 MM 0.0 0.0M 0.m\0.0 MM 0.0 H.0M m.m\0.0 MM N.0 00

0.0M 0.0\0.0 MM 0.0 0.0M ¢.m\0.0 MM 0.0 0.0M M.0\N.0 MM 0.0 00

0.0M M.m\0.0 MM «.0 0.0M M.m\0.0 MM M.0 ¢.NM 0.~\N.0 MM 0.0 00

0.00 0.~\0.0 MM 0.0 0.0M 0.~\¢.0 MM 0.0 0.0M 0.~\N.0 MM N.0 0H

«.mM N.~\0.0 MM e.N 0.NM ¢.~\0.0 MM 0.N 0.0M 0.~\N.0 MM 0.N 0
magnum nowumuoaaM wdfinmm coaumuoaaM moanmm GowumuoaaM mafia
mo MonaH mo MonaH mo MonaH

m «Magma N man-saw - Ens-mm
H aaog
Neoaawuaoov Muuoaauoaoo daemon: Mn naaHMuno aumn Maom .H Mamaaem<

-54-

 

 

 

 

 

92 M.S..- MM N; S: mime MM 0.0 2: 0.03.0 M» 0.0 . .30 SN
N.HN N.m\0.0 MM 0.0 0.0M 0.0\N.0 MM N.0 N.0H 0.¢\H.0 MM 0.0 00H
N.HN N.m\0.0 MM 0.0 0.0a 0.0\~.0 MM N.0 N.0M 0.¢\H.0 MM 0.0 00M
0.MN N.m\0.0 MM 0.0 0.0a 0.0\N.0 MM N.0 N.0M o.q\a.0 MM 0.0 00H
N.MN ¢.m\0.0 MM N.0 0.0a 0.M\H.0 MM H.0 0.NH ~.¢\H.0 MM 0.0 00
N.HN ¢.0\0.0 MM N.0 N.0H 0.0\H.0 MM H.0 0.NM ~.¢\H.0 MM 0.0 0N
0.H~ 0.0\0.0 MM N.0 0.0M 0.0\M.0 MM 0.0 ~.0H 0.0\H.0 MM 0.0 00
T: 0.30.0 MM 50 «.3 0.02.0 MM 0.0 0.3 502.0 MM 50 0.-
¢.NN 0.m\0.0 MM 0.0 «.00 0.N\H.0 MM 0.N 0.0M 0.0\H.0 MM 0.N 00
0.00 0.N\0.0 MM 0.N 0.0m N.N\H.0 MM 0.N o.o~ N.0\H.0 MM 0.N 0H
H.dm 0.N\0.0 MM ¢.N 0.H~ N.N\N.0 MM ¢.N ~.HN o.m\~.0 MM m.N 0
magnum nowumuoaoM .wdammm nowumuoaaM wawwmw nowumuoamM oeHH
mo MonnH mo MonaH mo NanaH
m aHMEmm N oHMEmm M oHMEmm
0 £004

 

AnomaHMMOOV MHuoEHHoHoo Haamnnz Mn nofiwmuno mumm MHOM .H Mamaomma

-65-

Appendix II. Pork data obtained by reflectance

 

 

 

 

 

Sample 1 Sample 2 Sample 3
Time L aL bL L aL bL L aL bL
Loin H

0 45.1 7.7 8.8 46.3 7.2 8.2 47.6 8.7 9.1
45.3 7.9 9.1 45.7 6.7 8.3 47.8 8.0 10.0
15 44.4 9.6 10.4 44.7 9.2 9.9 47.3 9.8 10.2
44.6 9.6 10.5 43.9 7.0 10.0 47.4 9.6 10.2
30 44.2 9.7 10.2 44.8 9.6 10.1 46.4 9.7 11.5
44.1 9.8 10.4 44.1 9.5 10.2 47.0 9.6 11.6
45 44.2 9.9 10.4 43.6 9.3 10.2 46.4 10.1 11.4
43.8 10.0 10.4 43.3 9.2 10.2 46.2 9.9 11.4
60 45.4 10.2 10.2 44.5 9.6 10.4 43.9 12.7 11.5
44.4 10.1 10.2 43.9 10.5 10.6 45.5 11.2 11.6
75 45.4 10. 10.7 43.8 10.3 10.3 43.5 12.8 11.5
44.1 10.1 10.6 43.4 10.0 10.5 45.5 11.0 11.8
90 46.4 9.6 10.3 43.9 10.4 10.5 44.7 11.6 10.2
44.2 9.8 10.8 43.8 10.5 10.6 45.0 11.6 11.6
105 45.3 9.6 10.2 42.9 9.8 10.6 44.9 12.0 11.8
43.4 9.7 10.2 42.4 9.8 11.0 45.0 11.1 12.0
120 45.4 10.1 10.3 42.7 10.0 10.5 44.6 10.5 11.8
44.9 9.6 10.4 42.4 9.8 10.4 41.5 11.7 12.0
150 45.1 11.1 10.7 44.2 11.5 10.5 44.9 11.2 11.8
44.1 11.1 11.3 42.7 11.5 10.8 41.3 12.0 12.0
24 hrs. 46.5 11.2 11.1 45.7 12.3 11.1 42.2 11.1 11.0
44.9 11.2 11.3 44.6 12.3 11.1 44.7 9.1 11.0

 

-66-

Pork data obtained by reflectance (continued)

Appendix II.

Sample 2 Sample 3

Sample 1

 

 

 

 

aL

aL

Time

 

Loin I

41.6
0

60

40.4
40.5

10.0
10.0

 

105

0
2
1

150

24 hrs.

 

-67-

Pork data obtained by reflectance (continued)

Sample 3

1e 2
aL

Sa

Sample 1

 

Appendix II.

bL

aL

 

bL

 

bL

aL

 

Time

 

Loin J

27

99

38

99

105

65
O
99

120

150

 

-68-

 

 

 

¢.¢H 0.0\N.m M 0.0 0.0a 0.0\0.m MM m.H 0.NM M.0\o.¢_MM H.H «.ma 0.0\¢.m MM N. 0.0a N.0\o.¢_MM H. .mnM 0N
¢.¢H 0.0\N.0 M 0.0 «.0H m.0\0.m MM 0.H 0.NM H.0\o.¢ MM H.H «.ma 0.0\¢.0.MM N. 0.0a N.0\o.¢_MM H. 00H
¢.¢H 0.0\N.0 M 0.0 N.0M 0.0\0.m MM 0.H 0.NH H.0\o.e MM H.H 0.NH 0.0\¢.0 MM N. 0.0a N.0\o.¢ MM H. 00H
0.0a 0.0\N.m M 0.0 H.0M H.0\0.m MM 0.H 0.NH H.0\0.¢ MM H.H 0.0M M.0\0.m MM 0. 0.0M 0.¢\o.¢ MM H. ONH
0.0M N.0\N.m M 0H 0.0M N.¢\0.m MM 0.H 0.NH H.0\o.¢.MM H.H 0.0M H.0\0.m MM 0. 0.0M 0.¢\o.¢ MM N. 00H
0.0a N.0\N.m M 0H 0.0M N.¢\0.0 MM 0.H 0.NH o.0\o.¢ MM 0.H N.0H o.0\¢.m.MM m. 0.0a 0.¢\o.¢ MM N. 00
0.NH N.¢\N.m M .0.0 N.0H 0.¢\0.0 MM 0.M 0.NM o.0\o.e MM.0.H 0.0M o.0\¢.m MM 0. 0.0a N.¢\o.¢.MM a. 0N
0.NH 0.¢\N.m M. 0.0 H.0N 0.¢\0.m MM 0.N H.0H q.¢\o.¢ MM N.H 0.0a 0.0\¢.0.MM 0. 0.0M 0.¢\o.¢ MM 0. 00
0.0M ¢.¢\N.m MM 0. 0.0N N.¢\0.m MM 0.H 0.0M N.¢\o.¢ MM 0.M 0.0N 0.¢\0.m MM 0. 0.0M ¢.¢\0.m MM 0. 0e
0.0M N.¢\0.m MM 0. N.HN 0.m\0.0 MM 0.H 0.0N H.q\o.¢ MM 0.N 0.HN H.¢\0.m MM o.M 0.0M H.¢\0.m MM ¢.H om
0.0N 0.0\0.m MM 0. N.NN 0.m\0.m MM 0.N 0.HN 0.0\H.q MM 0.N 0.NN 0.0\¢.m MM ¢.M 0.0M N.0\o.¢ MM 0.H 0H
0.HN N.0\0.m MM 0. 0.NN M.0\0.m MM H.m N.mN H.0\N.¢ MM 0.N n.0N H.0\¢.0_MM ¢.H M.MN 0.0\H.¢ MM 0.H 0
M 00M

magnum MOMMMMOGaM waammm nowumuonaM weanmm :oaumuoaaM magnum nowumMOGMM magnum SOHMMMOMMM 0809 u

mo 00 00 mo 00

MonaH MovaH MonaH NonaH ManaH

0 camewm a oaaewm 0 mamaam N oaaewm M oaaewm

 

Pi

MauoEHHoHoo Manama: Mn noaMMuno dune moon

.HMH MaeemMMM

-69-

 

 

 

 

0.0a 0.0\0.m MM 0. N.0H ¢.0\0.0 MM 0. 0.0M N.0\N.0 MM N. 0.0M N.0\H.¢ MM N. 0.0M 0.0\N.¢.MM N.H .MMM 0N
0.0a 0.0\0.0 MM 0. 0.0a N.0\N.0 MM 0. 0.0M N.0\N.m MM.N. H.0M 0.0\M.0_MM N. N.0M 0.0\N.¢ MM N.M 00M
0.0M 0.0\0.0 MM 0. 0.NH H.0\N.m MM 0. N.0M 0.0\N.0 MM 0. N.NM ¢.0\M.¢ MM H.H N.0H 0.0\N.a MM N.M 00M
0.NH q.0\0.0.MM 0.M 0.NH 0.0\N.m MM 0.M M.0M H.0\0.0 MM M.M 0.0M 0.0\M.¢ MM.0.H N.0M N.0\N.¢ MM_¢.H 0NM
0.0a H.0\0.m MM N.M 0.NH 0.0\N.0 MM H.M 0.0M N.0\0.m MM m.M 0.0M 0.e\M.¢ MM 0.H 0.0M 0.¢\N.¢ MM N.M 00H
0.0M 0.¢\0.m MM 0.M 0.NH 0.0\N.0 MM H.H 0.0M 0.0\N.m MM N.M 0.0M 0.¢\H.d MM 0.M 0.0M 0.0\N.¢ MM N.M 00
H.0M H.0\0.m MM 0.H 0.0M 0.0\N.m MM N.M H.0M N.0\N.0 MM 0.H 0.0M 0.¢\H.e MM 0.H 0.0M N.¢\N.u MM N.H 0N
0.0M q.e\0.0 MM 0.M N.0M 0.0\N.m MM N. 0.HN ¢.0\0.0 MM 0.N N.0N e.¢\H.e MM 0.N 0.0M N.¢\N.¢ MM N.H 00
H.MN 0.0\N.m MMO.N H.0H 0.¢\N.m MM 0.H 0.HN 0.0\0.m MM 0.N N.MN H.¢\H.¢ MM 0.N ¢.0N 0.¢\N.¢ MM H.N 00
o.«« «.a\0.m MM 0.« 0.0« m.e\a.m MM e.M m.m« m.a\0.m MM m.« M.M« o.a\M.e MM 0.« 0.0« m.e\«.e MM «.« 0m
0.«« o.e\0.m MM o.m a.-« «.e\«.m MM m.M M.m« 0.e\0.m MM o.m 0.«« 0.M\M.e MM «.m M.«« «.M\m.e.MM o.« 0M
0.0N 0.0\N.m MM N.N 0.0N N.0\N.m MM 0. 0.0N 0.0\0.m MM 0.N H.0N N.0\M.¢ MM 0.0 0.0N m.0\¢.¢ MM N.N 0
o nHM

uwuaemm aoaumuoaaM mainmm aoaumuoaaM wwwnmm aoaumuoaaM weanmm aoMuauoaoM \wwwwmm aoMumuoaaM mafia
mo mo mo mo mo

unxovaH MoeaH MonaH xaweH ManeH

0 oHaEmm a oHnEmm m oHaEmm N oHMEMm H mamaam

-’i

 

Anaaaauaoov MmuoeMMoHou Hammasz Mn noaamuno «use moon

.MHH xMeamMaMI

-70-

 

 

 

 

0.0H H.0\o.¢ MM N.M 0.0H N.0\m.¢ MM 0. 0.NH 0.0\H.¢ MM ¢.H N.0H H.0\m.e MM 0.N N.0H N.0\0.¢ MM 0. .mp5 0N
0.0a H.0\0.¢ MM ¢.H 0.0a H.0\m.d MM 0.H 0.0a 0.0\M.¢ MM 0.N 0.0N 0.0\m.e MM 0.N 0.0a 0.0\0.¢ MM 0. 00M
0.0M 0.0\0.¢ MM m.a 0.0a 0.0\0.¢ MM ¢.M H.0H 0.0\H.¢ MM N.N 0.0N 0.0\m.¢ MM N.N 0.0M 0.0\0.¢.MM 0.H 00Hm
M.MM 0.0\o.a MM «.M 0.0- o.0\m.a_MM 0.M 0.0M 0.0\M.a MM a.« «.M« 0.m\m.e_MM 0.« «.o« e.0\0.e MM M.M o«M
0.NH 0.0\o.¢ MM N.M 0.0M 0.0\m.¢ MM 0.M 0.0M 0.0\H.¢ MM 0.N 0.HN q.0\m.d MM 0.N 0.0N 0.0\0.¢ MM N.M 00M
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a AMM
memm nowumuoaoM waMnaM GoMumuoaoM maMnmm doaumuoaaM waawmm aowumuoaaM wawnmm nowuauonaM 08MB
mo mo Ma Ma Ma
mmeaH MonaH MonaH NonaH MonaH
0 oaaemm a owMEmm m oHeEMm N ammamm H aHMESO

F

 

Anosawuaoov MMuoEMMoaoo Haamqsz Mo mosMMuno aumn moom

.HHH MMeamaaM

-71-

  

 

m.AA 0.AN 0.0N 0.0A N.0A 0.0N N.0A 0.0A 0.0N N.0A N.0A 0.0N 0.0A N.0A 0.0N
m.AA 0.0N 0.NN 0.0A 0.0N 0.0N 0.0A 0.0N 0.¢N 0.0A N.0A N.0N N.0A N.0A 0.¢N .MMM «N

.OA N.0A N.0N A.oA 0.0A 0.NN N.oA 0.0A 0.0N N.0A 0.0N 0.0N o.AA 0.0N 0.0N
.0 0.0A 0.0N o.oA 0.0A 0.0N A.oA 0.0A 0.0N A.OA 0.0N o.0N 0.0A 0.0N 0.0N 00A

0
0
d.oA 0.0A N.0N A.oA N.0A 0.¢N N.0A N.0A A.¢N N.0A 0.0A 0.0N 0.0A 0.0A 0.0N 00A
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0.0A 0.0N 0.0A 0.NA N.0N N.0A N.0A 0.0N ¢.0A 0.NA N.0N 00

 

 

 

 

 

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M AHM

AA Am A AA Am A Am An A Am An A Am An A 08AM

0 oAaamm a oAMEmm m oAMemm N oAaEmm A oAaEmm

 

monmuoaAmoM MA noaAauno amen moom .>H MAnaaMQM

 

-72-

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«.mA N.0N m.AA 0.0N 0.0N 0.0A 0.0A 0.0N c.AA 0.0A 0.0N 0.0A N.0A 0.0N 00

 

 

 

 

 

 

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-73-

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-76-

 

 

 

 

 

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-77-

Appexdix VI. Lamb data obtained by reflectance

 

 

 

 

Sample 1 Sagple 2 Sample 3
Time L aL bL L aL bL L aL bL
‘Rack D
0 25.2 13 9 9.0 26 1 13 9 10.0 26.4 14.3 10 1
25 4 14 2 9.7 26 2 14 0 10.1 26.0 14 0 10 2
15 26.3 16.9 10.4 25.5 16.3 10.8 26.7 15.6 11.0
25.7 16.4 10.8 25 4 16.5 11.0 26 6 15 9 11.0
30 25.3 17.3 11.0 25.9 17.6 11.2 25.8 17.0 11.3
25.2 17 5 11 0 25.8 17.5 11.3 26.1 17 2 11 3

45 25.1 17.9 11.2 26.0 18.0 11.3 26.4 17.6 11.4
60 25.8 18.7 11.5 25.8 18.3 11.3 26.6
75 25.8 18.6 11.2 26.3 17.8 11.2 26.5 17.6 11.3
90 25.4 19.0 10.8 25.8 17.9 11.4 26.0 17.9 11.3
105 25.7 19.1 11.4 25.9 18.0 11.3 26.3 17.8 11.2

120 25.3 19.3 11.4 25.8 18.1 11.4 26.4 17.9 11.3

 

24 hrs. 25.9 18.9 11.2 25.8 18.0 11.3 26.2 18.2 11.4

 

-78..

Appendix VI. Lamb data obtained by reflectance (continued)

 

 

 

 

Sample 1 Sample 2 Sample 3
Time L aL bL L aL bL L aL bL
Rack E
0 27.1 14 5 25 7 14.7 .

15 26.8 17.8
30 26.7 18.4 11.5 25.2 17.4 10.2 25.2 17.0 10.0
45 27.0 18.6 11.6 25.7 18.4 11.2 24.9 17.8 11.0
60 26.5 18.8 11.4 26.0 18.9 11.3 24.9 18.7 11.0
75 25.3 19.1 10.8 25.2 18.9 11.3 24.7 18.9 11.3
90 26.1 19.5 11.7 24.7 18.7 11.1 24.6 18.9 10.3

105 24.5 18.7 10.3 25.2 19.0 11.1 24.5 18.3 10.9

 

120 26.1 19.8 11.6 24.9 19.1 11.0 24.1 18.3 10.9

24 hrs. 27.5 20.5 12.6 26.1 20.3 11.3 26.3 19.9 11.0

 

-79-

Appendix VI. Lamb data obtained by reflectance (continued)

 

 

 

 

.Sample 1 Samp1e 2 Sample 3
Time L aL bL L aL bL L aL bL
Rack F
0 25 3 14.0 9 3 23.3 13.7 9 0 25.0 14.3 9.5
23 9 13.9 9.2 23.3 14.1 8.8 24.3 14 1 9.3
15 24.3 15.4 9 6 24 2 15.7 10.0 24.8 16 8 10.4
23 6 15 3 9 7 24 6 16.2 10.2 24 2 16 5 10.3
30 25.2 16.8 10.8 23.8 16.7 10.4 25.0 17.7 11.0
24.6 16 6 10.5 24.5 17.0 10.6 24 8 17.7 11 0

45 25.5 17.5 11.2 24.3 17.5 10.8 24.7 18.3 11.0
60 23.8 17.3 10.6 23.8 18.1 10.7 24.9 18.9 11.1
75 24.2 17.7 10.0 25.6 18.4 10.6 23.9 17.4 10.5
90 24.8 18.3 10.3 25.0 17.3 10.0 25.1 19.0 10.5
105 23.9 17.5 i.

120 23.5 18.4 10.2 24.5 18.5 10.5 24.8 19.8 11.1
0 O .2 O O

 

24 hrs. 25.4 19.3 11.2 24.7 19.7 11.3 25.7 20.0 11.6

 

-30-

Appendix VII. Correlation of myoglobin concentration and Index of Fading

 

 

in lamb.

Rack No. Index of Fading Myoglobin (mngg;l

2 14.7 ' 1.66

3 15.8 2.67

4 16.8 2.55

5 18.3 3.29

6 15.9 3.20
g x2 = 1335.67 g Y2 = 37.45
g x = 81.5 g Y - 13.37
(2 x)2 = 6642.25 ( S Y)2 = 178.75
g xy = 220.515
(S xxg Y) = 1092.10

N = 5

N S x2 - (f x)2 = 6678.35 - 6642.25 = 36.10
N S Y2 - (g Y)2 = 187.25 - 178.75 = 8.50

N 5 XY = 1102.57

 

Nf XY - (S X)(€ Y) = 1102.57 - 1092.10 = 10.47

_N€xy- (z xxiY)
r‘flNéXl- <2 XVJLNEYZ- <22?)

10.47

(36.10)(8.50) ‘ '596

-31-

Appendix VIII. Correlation of myoglobin concentration and aL in lamb.

Rack No. aL ‘Myoglobin (mg./g.)
2 14.0 1.66
3 14.7 2.67
4 14.1 2.55
5 14.1 3.29
6 14.0 3.20

r = .604

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