Sampling and aging effects on beef longissimus color stability measurements


King, D.A.; Shackelford, S.D.; Kalchayanand, N.; Wheeler, T.L.

Journal of Animal Science 90(10): 3596-3605

2013


The present study was conducted to determine the repeatability of color stability measurements and to evaluate relationships among color stability data collected under differing sampling and aging protocols. Beef (Bos taurus) carcasses (n = 100) were selected at grading in a commercial facility, after which a LM steak was removed from the 13th rib of each carcass and immediately placed in simulated retail display. Steaks were removed from the remainder of each loin after 14 (duplicate) and 35 d of aging and placed in display. Color attributes [L*, a*, b*, hue angle, chroma, K/S(572)/K/S(525), and overall color change (ΔE)] were determined on d 0, 1, 4, 7, and 11 of display. Duplicate 14-d aged steaks differed (P < 0.05) initially with regard to L*, b*, hue angle, chroma, K/ S(572)/K/S(525), and ΔE. However, changes in these attributes during display were equivalent in the duplicate steaks. Furthermore, repeatability estimates were high for all attributes, particularly when measured late in the display period (R = 0.55 to 0.97 on d 4, 7, and 11 of display). Differences in the trends associated with color change of steaks removed from the carcass after grading and those aged for 14 d were generally insignificant. Changes in color attributes of steaks aged for 35 d before simulated retail display generally were much more rapid than those obtained after grading or those aged for 14 d. Despite differences in the rate of discoloration during simulated retail display, color attributes were moderately to highly correlated (P < 0.05) between aging treatments, though the degree of correlation between attributes varied across days of display. In steaks collected after grading and those aged for 14 d, the greatest correlation was observed in the latter part of the display period with coefficients ranging from 0.61 to 0.94 on d 4, 7, and 11 of display. The greatest correlation between steaks aged for 14 d and those aged for 35 d were detected in the middle portion of the display period, presumably because many steaks aged for 35 d had reached an ultimate level of discoloration by d 11 of display with correlation coefficients ranging from 0.51 to 0.95 on d 4 and 7 of display. Thus, these results indicate that color stability data is highly repeatable and that, although aging impacts color-life, animal variation is consistent across aging times. Furthermore, steaks obtained from carcasses after grading can provide color stability evaluations applicable to steaks from aged subprimals.

Sampling
and
aging
effects
on
beef
longissimus
color
stability
measurements
i
D.
A.
King,
2
S.
D.
Shackelford,
N.
Kalchayanand,
and
T.
L.
Wheeler
USDA
3
—ARS,
Roman
L.
Hruska
U.S.
Meat
Animal
Research
Center,
Meat
Safety
and
Quality
Research
Unit,
Clay
Center,
NE
68933-0166
ABSTRACT:
The
present
study
was
conducted
to
determine
the
repeatability
of
color
stability
mea-
surements
and
to
evaluate
relationships
among
color
stability
data
collected
under
differing
sampling
and
aging
protocols.
Beef
(Bos
taurus)
carcasses
(n
=
100)
were
selected
at
grading
in
a
commercial
facility,
after
which
a
LM
steak
was
removed
from
the
13th
rib
of
each
carcass
and
immediately
placed
in
simulated
retail
display.
Steaks
were
removed
from
the
remain-
der
of
each
loin
after
14
(duplicate)
and
35
d
of
aging
and
placed
in
display.
Color
attributes
[L*,
a*,
b*,
hue
angle,
chroma,
K/5
572
/K/5
525
,
and
overall
color
change
(AE)]
were
determined
on
d
0,
1,
4,
7,
and
11
of
display.
Duplicate
14-d
aged
steaks
differed
(P
<
0.05)
initially
with
regard
to
L*,
b*,
hue
angle,
chroma,
K/
5
572
/K/5
525
,
and
AE.
However,
changes
in
these
attri-
butes
during
display
were
equivalent
in
the
duplicate
steaks.
Furthermore,
repeatability
estimates
were
high
for
all
attributes,
particularly
when
measured
late
in
the
display
period
(R
=
0.55
to
0.97
on
d
4,
7,
and
11
of
dis-
play).
Differences
in
the
trends
associated
with
color
change
of
steaks
removed
from
the
carcass
after
grad-
ing
and
those
aged
for
14
d
were
generally
insignifi-
cant.
Changes
in
color
attributes
of
steaks
aged
for
35
d
before
simulated
retail
display
generally
were
much
more
rapid
than
those
obtained
after
grading
or
those
aged
for
14
d.
Despite
differences
in
the
rate
of
dis-
coloration
during
simulated
retail
display,
color
attri-
butes
were
moderately
to
highly
correlated
(P
<
0.05)
between
aging
treatments,
though
the
degree
of
corre-
lation
between
attributes
varied
across
days
of
display.
In
steaks
collected
after
grading
and
those
aged
for
14
d,
the
greatest
correlation
was
observed
in
the
latter
part
of
the
display
period
with
coefficients
ranging
from
0.61
to
0.94
on
d
4,
7,
and
11
of
display.
The
great-
est
correlation
between
steaks
aged
for
14
d
and
those
aged
for
35
d
were
detected
in
the
middle
portion
of
the
display
period,
presumably
because
many
steaks
aged
for
35
d
had
reached
an
ultimate
level
of
discoloration
by
d
11
of
display
with
correlation
coefficients
ranging
from
0.51
to
0.95
on
d
4
and
7
of
display.
Thus,
these
results
indicate
that
color
stability
data
is
highly
repeat-
able
and
that,
although
aging
impacts
color-life,
animal
variation
is
consistent
across
aging
times.
Furthermore,
steaks
obtained
from
carcasses
after
grading
can
pro-
vide
color
stability
evaluations
applicable
to
steaks
from
aged
subprimals.
Key
words:
aging,
beef,
color
stability,
meat
color,
repeatability,
sampling
©
2012
American
Society
of
Animal
Science.
All
rights
reserved.
J.
Anim.
Sci.
2012.90:3596-3605
doi:10.2527/jas2011-4871
INTRODUCTION
1
Mention
of
trade
names
or
commercial
products
in
this
publication
is
solely
for
the
purpose
of
providing
specific
information
and
does
not
imply
recommendation
or
endorsement
by
the
U.S.
Department
of
Agriculture
The
authors
are
grateful
to
Patty
Beska,
Kristen
Ostdiek,
Kathy
Mihm,
and
Pat
Tammen
of
the
U.S.
Meat
Animal
Research
Center
for
their
assistance
in
the
execution
of
this
experiment
and
to
Marilyn
Bierman
of
the
U.S.
Meat
Animal
Research
Center
for
her
secretarial
assistance.
2
Corresponding
author:
andy.king@ars.usda.gov
3
USDA
is
an
equal
opportunity
provider
and
employer.
Received
November
2,
2011.
Accepted
March
23,
2012.
Previous
results
from
our
laboratory
have
identified
inherent
variation
in
lean
color
stability
in
addition
to
environmental
effects
which,
to
some
extent,
are
ge-
netically
regulated
(King
et
al.,
2010,
2011a,b).
Thus,
investigation
of
the
genetic
x
environment
interactions
regulating
lean
color
stability,
as
well
as
the
develop-
ment
of
non-invasive
technology
to
predict
lean
color
stability
as
beef
carcasses
are
presented
for
grading,
is
warranted.
3596
Aging
effects
on
beef
color
stability
3597
In
such
studies,
data
must
be
collected
on
numer-
ous
samples
in
a
manner
representative
of
commercial
conditions
and
must
be
repeatable.
Postmortem
aging
varies
widely
across
the
industry,
with
product available
at
retail
outlets
after
aging
times
from
3-
to
70-d
post-
mortem
(Voges
et
al.,
2007).
Postmortem
aging
has
been
reported
to
affect
the
biochemical
processes
determin-
ing
lean
color
stability
(Ledward,
1985;
Feldhusen
et
al.,
1995;
Tang
et
al.,
2005),
though
few
investigations
have
compared
aging
times
long
enough
to
be
relevant
to
current
commercial
practices.
Our
protocols
to
collect
tenderness
data
for
genomics
and
tenderness
prediction
studies
involve
removing
a
steak
from
the
13th
rib
of
each
carcass
after
grading,
which
is
subsequently
aged
until
14
d
postmortem.
By
measuring
color
stability
dur-
ing
aging,
our
genomics
research
could
be
expanded
to
lean
color
stability
at
minimal
cost.
Objectives
of
the
present
experiment
were
to
evaluate
the
repeatability
of
color
stability
measurements,
as
well
as
to
determine
whether
color
stability
measurements
collected
under
differing
sampling
and
aging
protocols
produced
results
that
are
consistent
with
those
resulting
from
other
protocols.
Furthermore,
we
investigated
rela-
tionships
between
lean
color
stability
data
obtained
from
steaks
that
had
been
aged
for
14
or
35
d
before
simu-
lated
retail
display.
Finally,
color
stability
assessments
on
steaks
removed
from
carcasses
after
grading
were
com-
pared
with
those
from
steaks
from
subprimals
aged
in
vacuum
packages
before
being
placed
in
simulated
retail
display.
MATERIALS
AND
METHODS
Animal
care
and
use
approval
was
not
obtained
for
this
experiment
because
samples
for
this
experiment
were
acquired
postmortem
from
a
federally-inspected
commercial
processing
facility.
Carcasses
(n
=
100)
were
selected
from
a
commer-
cial
processing
facility
as
they
were
presented
for
grad-
ing
at
approximately
96
h
postmortem.
Carcasses
(U.S.
Choice)
were
selected
across
numerous
production
lots
to
have
normal
LM
meat
color
and
marbling
scores
be-
tween
Small
00
and
Sma11
50
.
After
grading,
carcasses
were
placed
on
a
stationary
rail
where
a
2.54-cm-thick
steak
was
removed
from
the
strip
loin
(13th
rib)
of
the
left
side
of
each
carcass.
Care
was
taken
to
ensure
that
the
freshly
cut
surface
of
the
steak
(posterior
surface)
was
not
touched
by
the
investigators
or
other
objects.
Steaks
were
placed
in
plastic
trays
in
an
insulated
con-
tainer
with
ice-packs.
The
plastic
trays
were
deeper
than
the
thickness
of
the
steak,
and
layers
of
trays
were
sepa-
rated
with
cardboard
so
that
the
freshly-cut,
posterior
surface
of
the
steak was
not
contacted
by
other
steaks
or
trays.
Steaks
were
transported
to
the
U.S.
Meat
Animal
Research
Center
(USMARC)
meat
laboratory,
over-
wrapped,
and
placed
in
simulated
retail
display.
The
re-
maining
portion
of
the
strip
loin
was
vacuum
packaged
after
fabrication
and
transported,
under
refrigeration,
to
the
USMARC
meat
laboratory.
At
14
d
postmortem,
the
vacuum
packages
were
opened
and
a
1.27-cm-thick
face
cut
was
removed
from
the
anterior
aspect
and
used
for
myoglobin
and
pH
determination.
Then
two
2.54-cm-
thick
steaks
were
removed,
overwrapped,
and
placed
in
simulated
retail
display
so
that
the
most
anterior
sur-
face
of
each
steak
was
exposed
to
lights
during
display.
Ideally,
repeatability
would
be
determined
by
measuring
the
same
experimental
unit
multiple
times.
In
the
case
of
steaks
in
simulated
retail
display,
this
is
not
possible.
Thus,
adjacent
steaks
were
used
to
minimize
potential
lo-
cation
effects
for
repeatability
estimates.
The
remaining
strip
loin
was
re-vacuum
packaged
(3-Mil
vacuum
bags,
Prime
Source,
Kansas
City,
MO;
oxygen
transmission
rate
=
0
cc
100
cm
-2
24
h
-1
)
and
stored
for
an
ad-
ditional
21
d
until
35
d
postmortem.
After
the
additional
aging,
the
packages
were
opened
and,
after
removing
a
1.27-cm-thick
slice,
a
steak was
cut
and
placed
in
simu-
lated
retail
display.
Simulated
Retail
Display
Steaks
were
placed
on
polystyrene
trays
with
soaker
pads
and
overwrapped
with
oxygen-permeable
poly-
vinylchloride
film
(Stretchable
meat
film
55003815;
Prime
Source,
St.
Louis,
MO;
oxygen
transmission
rate
=
1.4
mL
cm
-2
24
h
-1
at
23
°
C).
Steaks
were
placed
under
continuous
fluorescent
lighting
(color
temperature
=
3500
K;
color
rendering
index
=
86;
32
W
T8
Ecolux
bulb,
model
F32T8/SPX35
GE;
GE
Lighting,
Cleveland,
OH),
and
light
intensity
at
the
meat
surface
was
approxi-
mately
2000
lux.
Display
was
conducted
in
a
refriger-
ated
room
(1°C),
and
no
temperature
fluctuations
associ-
ated
with
defrost
cycles
were
encountered.
Steaks
cut
after
aging
were
allowed
to
bloom
for
at
least
2
h
after
being
packaged
before
color
measure-
ments
were
taken.
For
steaks
removed
from
the
carcass
after
grading,
initial
color
variables
were
measured
ap-
proximately
4
h
after
being
removed
from
the
carcass.
This
additional
bloom
time
was
due
to
the
time
required
to
transport
the
steaks
from
the
packing
plant
to
our
meat
laboratory.
Instrumental
color
readings
were
taken
on
each
steak
on
d
0,
1,
4,
7,
and
11
using
a
Hunter
Miniscan
XE
Plus
colorimeter
(HunterLab,
Reston,
VA)
with
a
25-mm
port.
The
colorimeter
was
set
to
collect
spectral
data
with
Illuminant
A
and
a
10°
observer.
Commission
Internationale
de
l'Eclairage
(CIE)
lightness
(L*),
red-
ness
(a*),
and
yellowness
(b*)
color-space
values
were
reported
as
the
average
of
duplicate
readings
taken
on
each
steak.
Chroma
(color
intensity;
also
known
as
satu-
3598
King
et
al.
ration
index)
was
calculated
as:
[(a*
2
+
b*
2
)
0
.
5
].
Hue
angle
(redness)
was
calculated
as:
[Arctangent(b*/a*)
x
180/3.142].
Overall
color
change
(AE)
was
calculated
as
(AL*
2
+
Aa*
2
+
Ab*
2
)
0
.
5
,
where
AT,*,
Aa
*,
and
Ab*
are
the
difference
between
d
0
and
d
1,
4,
7,
and
11
values
for
L*,
a*,
and
b*,
respectively.
Additionally,
spectral
data
were
used
to
calculate
K/S
572
/K/S
525
ratios
to
es-
timate
accumulation
of
metmyoglobin
as
described
by
Hunt
et
al.
(1991).
pH
and
Myoglobin
Concentration
Myoglobin
concentration
and
pH
were
measured
in
duplicate
on
2
different
occasions
to
test
repeatability
of
these
measurements.
The
1.27-cm-thick
slice
removed
from
each
strip
loin
before
the
14-d
aged
steaks
were
cut
was
trimmed
free
of
external
fat
and
epimysium,
diced,
and
pulverized
in
liquid
nitrogen
to
produce
a
homogenous
powder.
Muscle
pH
was
determined
as
prescribed
by
Bendall
(1973).
Duplicate
2.5-g
samples
were
homogenized
in
10
volumes
of
a
5-mill
iodoac-
etate,
150-mM
KC1
solution
(pH
=
7.0).
Homogenates
were
allowed
to
rest
for
a
minimum
of
1
h
at
room
tem-
perature,
mixed
via
vortexing,
and
pH
was
measured
us-
ing
a
semi-micro
combination
electrode
(Corning
Inc.,
Corning,
NY)
attached
to
a
Corning
125
pH
meter.
Myoglobin
was
extracted
and
quantified
follow-
ing
the
method
described
by
Warris
(1979)
as
modified
by
Hunt
et
al.
(1999).
Briefly,
duplicate
2.5-g
samples
were
homogenized
in
10
volumes
of
40-mM
potassium
phosphate
buffer
(pH
=
6.8).
Homogenates
were
held
on
ice
for
1
h
to
allow
complete
pigment
extraction
before
centrifugation
(15,000
x
g)
for
30
min
at
4°C.
Supernatant
(1.5
mL)
was
syringe
filtered
(Nalgene
0.45µm,
surfactant-free
cellulose
acetate
membrane;
Thermo
Fisher
Scientific,
Rochester,
NY)
into
a
4-mL
cuvette
with
1
mL
of
40-mM
phosphate
buffer
and
0.5
mL
sodium
hydrosulfite
(10
mg/mL).
Absorbance
spec-
tra
from
400
to
700
nm
were
scanned
on
each
sample
using
a
DU
640
spectrophotometer
(Beckman
Coulter,
Inc,
Fullerton,
CA).
Once
samples
were
verified
to
be
in
the
reduced
state
(absorbance
peak
within
2
nm
of
433),
extracted
pigment
concentration
was
calculated
using
the
absorbance
at
433
nm,
a
molar
extinction
coefficient
of
114,000
M
-1
cm
-1
,
the
molecular
weight
of
myo-
globin
(16,800),
and
the
appropriate
dilution
factor.
Aerobic
Plate
Counts
and
Lactic
Acid
Bacteria
Counts
Aerobic
and
lactic
acid
bacteria
counts
were
deter-
mined
on
the
steaks
aged
for
14
d
before
simulated
retail
display
to
ensure
that
the
discoloration
observed
during
the
experiment
was
not
the
result
of
microbial
contami-
nation.
When
the
first
of
the
2
replicate
steaks
was
cut,
the
posterior
(bottom)
surface
was
swabbed
(10
cm
2
)
with
a
sterile
cotton
swab
(Puritan
Medical
Products,
Guilford,
ME)
moistened
with
maximum
recovery
dilu-
ents
(MRD;
Remel,
Lenexa,
KS).
Care
was
taken
so
that
this
surface
did
not
contact
any
surface
other
than
the
knife
before
being
swabbed,
and
that
this
surface
was
placed
directly
on
the
foam
tray
immediately
after
swab-
bing.
At
the
conclusion
of
display
(d
11),
the
anterior
(top)
surface
of
the
second
steak
was
swabbed
in
the
same
manner.
Thus,
the
surfaces
sampled
on
d
0
and
11
of
display
represented
both
sides
of
the
knife
cut.
After
sampling,
the
cotton
swab
was
placed
into
2
mL
of
MRD
and
mixed
for
1
min
via
vortexing.
One
milliliter
of
the
mixed
sample
was
enumerated
on
pet-
rifilm
aerobic
count
plate
(3M
Microbiology,
St.
Paul,
MN)
and
incubated
as
recommended
by
the
manufac-
turer.
Colonies
were
counted
(colony
forming
unit,
CFU)
using
a
petrifilm
plate
reader
(3M).
For
lactic
acid
bacteria
counts,
an
aliquot
of
0.5
mL
of
the
sample
was
mixed
with
0.5
mL
of
2x
concentration
of
DeMan,
Rogosa,
Sharpe
(MRS)
broth
(Difco,
Becton
Dickinson,
Sparks,
MD),
and
1
mL
was
enumerated
on
petrifilm
aerobic
count
plate.
Plates
were
incubated
(32°C
for
48
h)
as
recommended
by
the
manufacturer,
and
the
colo-
nies
were
hand
counted.
All
the
bacterial
counts
were
transformed
and
reported
as
log
CFU/cm
2
values.
Statistical
Analysis
The
repeatability
of
color
attributes
during
simulat-
ed
retail
display
was
assessed
by
subjecting
duplicate
steaks
that
had
been
aged
for
14
d
from
each
strip
loin
to
simulated
retail
display.
These
data
were
analyzed
as
a
randomized
complete
block
with
repeated
measures
us-
ing
the
PROC
MIXED
procedure
(SAS
Inst.
Inc.,
Cary,
NC).
The
model
tested
the
fixed
effects
of
the
steak,
day
of
display,
and
their
interaction.
Carcass
was
included
as
a
random
effect.
Day
of
display
was
modeled
with
a
spatial
power
covariance
structure.
Least-squares
means
were
generated
for
the
steak
x
day
interaction
of
each
trait. Because
the
shape
of
the
discoloration
curves
was
of
primary
importance,
a
second
model
was
fit
with
the
same
random
effect
and
covariance
structure
described
above
that
tested
the
fixed
effect
of
steak,
the
linear
and
quadratic
polynomials
of
display
day,
and
the
interaction
between
the
polynomials
of
display
day
and
steak.
Lack-
of-fit
tests
were
used
to
determine
if
cubic
effects
were
needed.
Nonsignificant
(P
>
0.05)
terms
were
removed
from
the
model;
thus,
the
simplest
regression
equations
describing
the
changes
in
each
color
trait
and
the
re-
lationship
between
the
duplicate
steaks
are
presented.
Furthermore,
variance
component
estimates
were
calcu-
lated
separately
for
each
color
attribute
on
each
day
of
display
using
the
PROC
VARCOMP
procedure
of
SAS.
Aging
effects
on
beef
color
stability
3599
Repeatability
was
calculated
as
(carcass
0
2
+
steak
loca-
tion
0
2
)/(carcass
0
2
+
steak
location
0
2
+
error
0
2
).
The
effects
of
aging
were
determined
by
comparing
the
color
attributes
of
the
steaks
collected
after
grading,
steaks
aged
for
35
d,
and
the
mean
of
the
duplicate
steaks
aged
for
14
d
using
the
previously
described
approach.
When
the
regression
analysis
indicated
that
separate
in-
tercepts
and/or
0-coefficients
were
required
to
describe
the
color
change
in
steaks
aged
for
different
time
peri-
ods,
linear
orthogonal
contrasts
were
used
to
determine
if
the
intercepts
or
0-coefficients
associated
with
color
change
of
steaks
from
the
3
aging
and
sampling
treat-
ments
differed
from
one
another.
When
testing
mean
differences
at
a
given
time
of
display
was
deemed
nec-
essary,
the
mean
was
projected
for
each
equation
at
the
given
time
point,
and
differences
were
tested
using
es-
timate
statements.
A
significance
level
of
0.05
was
used
for
all
judgments
of
statistical
significance.
Pearson
cor-
relation
coefficients
were
obtained
for
color
attributes
between
aging
treatments
on
each
day
of
display
using
the
PROC
CORR
procedure
of
SAS.
RESULTS
AND
DISCUSSION
Table
1
indicates
that
aerobic
plate
counts
and
lactic
acid
bacteria
counts
were
low
at
the
initiation
of
display.
Lactic
acid
bacteria
counts
did
not
change
(1
3
>
0.05)
dur-
ing
the
display
period.
Aerobic
plate
counts
increased
(P
<
0.05)
during
display,
but
were
still
low
on
d
11
of
display
and
were
far
short
of
counts
that
would
indicate
spoilage
(10
6
CFU/cm
2
;
Ingram
and
Dainty,
1971).
Furthermore,
these
counts
were
not
correlated
to
any
color
variables
during
display
(1
3
>
0.05;
data
not
shown).
Thus,
it
can
be
concluded
that
microbial
contamination
did
not
con-
tribute
to
the
color
changes
observed
in
this
experiment.
Figure
1
presents
the
least
squares
means
for
the
color
traits
collected
on
these
replicate
steaks
as
well
as
the
regression
equations
that
describe
the
changes
in
these
traits
during
simulated
retail
display.
The
intercept
values
for
the
replicate
steaks
differed
(P
<
0.05)
with
regard
to
L*,
b*,
hue
angle,
chroma
and
K/S
572
/K/S
525
values,
although
the
magnitude
of
these
differences
were
generally
small
(Figure
1).
In
contrast,
the
intercepts
for
Table
1.
Least-squares
means
for
aerobic
plate
counts
and
lactic
acid
bacteria
counts
of
LM
steaks
aged
for
14
d
before
simulated
retail
display
on
d
0
and
11
of
display
Day
of
display
Aerobic
plate
count,
log
CFU/cm
2
Lactic
acid
bacteria,
log
CFU/cm
2
d0
0.44
0.37
d11
1.30
0.29
SEM
0.10
0.05
P>F
<0.001
0.26
a*
values
(Figure
1B)
and
overall
color
change
(Figure
1G)
did
not
differ
(1
3
>
0.05)
between
the
replicate
steaks.
Although
initial
color
differed,
the
13-coefficients
for
the
regression
equations
describing
the
change
in
the
color
attributes
examined
in
this
study
during
display
did
not
differ
between
replicates,
indicating
the
color
change
during
display
was
equal
in
the
paired
steaks.
Trends
associated
with
a*,
hue
angle,
and
K/S
572
/K/
S
525
during
display
were
characterized
by
slow
changes
early
in
the
display
period
with
the
rate
of
change
in-
creasing
as
display
time
increased
(Figure
1).
Trends
as-
sociated
with
b*
(Figure
1C)
and
chroma
(Figure
1E)
had
a
similar
delay
phase
at
the
beginning
of
display,
a
rapid
decline
phase,
and
finally,
a
time
of
very
little
change
late
in
the
display
period.
Overall
color
change
increased
linearly
throughout
display
(Figure
1G).
Changes
in
L*
values
were
small,
but
the
decline
oc-
curred
more
rapidly
early
in
the
display
period
than
in
the
later
part
of
the
display
period
(Figure
1A).
Myoglobin
concentration
and
muscle
pH
were
also
measured
in
duplicate
(Table
2),
although
the
du-
plicate
samples
were
taken
from
the
same
steak.
After
this
steak
was
homogenized,
sampling
and
assays
were
done
on
separate
days
for
the
replicate
samples
(Table
2).
The
replicates
did
not
differ
with
regard
to
myoglo-
bin
concentration
(P
=
0.96).
However,
pH
did
differ
between
replicate
sample
(P
<
0.05),
even
though
this
difference
was
extremely
small
(0.02
units)
and
likely
not
of
practical
importance.
The
mechanism
resulting
in
differences
in
color
be-
tween
steaks
taken
in
such
close
proximity
(steak
sur-
faces
were
2.54
cm
apart)
to
one
another
is
not
clear.
However,
the
differences
between
the
replicate
steaks
existed
at
the
beginning
of
display
and
remained
con-
stant
throughout
the
display
period.
This
is
supported
by
the
repeatability
estimates
of
color
attributes
presented
in
Table
3.
Differences
between
steak
locations
so
close
in
proximity
highlight
the
need
to
consider
steak
loca-
tion
during
experimental
design.
These
results
indicate
that
steak
locations
should
be
standardized,
or
when
multiple
steaks
are
used
from
a
muscle,
blocked
across
treatments
to
avoid
biased
results.
Repeatability
was
high
for
L*
and
hue
angle,
and
K/5
572
/K/5
525
values
on
all
days
of
display.
Values
for
a*,
b*,
chroma,
and
AE
were
moderate
to
low
in
repeatability
on
d
0
or
1
of
display,
but
were
highly
repeatable
on
d
4
and
7
of
dis-
play.
All
of
the
attributes,
except
b*
and
chroma,
were
still
highly
repeatable
on
d
11
of
display,
although
the
repeatability
estimates
were
somewhat
lower
for
all
at-
tributes
except
L*
on
d
11
compared
with
d
7
values.
The
increase,
and
subsequent
decrease,
in
repeatability
as
the
display
period
progressed
may
be
due
to
increased
variation
among
carcasses
in
these
traits
as
display
pro-
gressed,
and
then
less
variation
as
steaks
reached
an
ul-
3600
King
et
al.
40
35
a
.30
-
I
25
50
35
-
A
45
-
_
_____
_________
ReplicateA
=
45.05
-
0.94*day
+
0.05*day"2
Replicate
B
--
=
45.92
-
0.94*day
+
0.05*day.2
.3
20
a.
le
15
30
25
B
20
15
10
0
1
2
3
4
5
6
7
8
9
10
11
Day
of
display
30
-
C
25
20
ReplicateA
-6*
=25.92
+
0.10`day
-
0.22*d
al/AZ
+
0.01*day^3
Replicate
--
=27.65
0.10*day
-
0.22*dayA2
+
0.01.•clay*3
5
-
0
0
1
2
3
4
5
6
7
8
9
10
11
Day
of
display
45
ReplicateA
A
Replicate
B
10
-
-a'
=
32.5
-1.25*day-0.41`day.2
5-
0
I.
2
3
4
5
6
7
8
9
10
11
Day
of
display
60
-
D
so
40
N
I
30
-
Replicate
1
-
HA
=
34.5
+
0.21
Y
day
+
012
day*2
20
-
Replicate
2
--
HA=
37.9
+
0.21
day
+
0.12
.day"2
10
-
0
1
2
3
4
5
6
7
8
9
10
11
Day
of
display
1.4
1.2
rat
35
-
30
-
g
25
6
20
-
15
-
10
-
5
-
0
0
0.8
-
‘___.___
1-
ReplicateA
-
MMB
=
1.22
-
0.02'day
-
0.003*day"2.
A
Replicate
B
--
MMB
=
1.12
-
0.02*day
-
0.0O3*day"2
Replicate
A
-C
=
41.7-
0.41'day
-
0.30
clay"2
+0.02*day"3
Replicate
B
--
C
=
42.5-
0.41*day
-
0.30*day^2
+0.02*day".3
1
2
3
4
5
6
7
8
9
10
11
Day
of
display
25
Replicate
A
G
20
-DE
=
0.05
+
1.76.day
Replicate
8
--
DE
=
0.05
+
1.93*day
:4:
15
8
E
10
5
O
1
2
3
4
5
6
7
8
9
10
11
Day
of
display
0.6
0.4
-
0.2
-
0
O
1
2
3
4
5
6
7
7
8
9
10
11
Day
of
display
Figure
1.
Least-squares
means
and
predicted
trends
of
color
attributes
of
replicate
LM steaks
during
11
d
of
simulated
retail
display
at
14
d
postmortem.
HA
=
hue
angle;
MMB
=
Metmyoglobin
content
(estimated
by
K/S
572
/K/S
525
ratios;
DE
=
AE
(overall
color
change).
Aging
effects
on
beef
color
stability
3601
Table
2.
Least-squares
means
for
myoglobin
concentra-
tion
and
pH
of
replicate
LM
samples
Item
Myoglobin,
mg/g
Replicate
A
4.22
Replicate
B
4.22
SEM
0.07
P>
F
0.96
timate amount
of
discoloration.
Measurements
for
both
myoglobin
concentration
and
pH
were
highly
repeatable.
Thus,
these
results
suggest
that
measurements
made
with
regard
to
beef
color
stability
during
display
studies
are
sufficiently
repeatable
for
use
in
phenomic
and
genomic
investigations
of
these
traits.
Sampling
and
Aging
Effects
on
Lean
Color
Stability
To
efficiently
conduct
large-scale
genetic
stud-
ies
of
color
stability
requires
an
economical
approach.
Removing
a
single
steak
from
a
ribbed
carcass
is
a
much
more
economical
option
than
obtaining
the
entire
strip
loin.
But,
removing
that
steak
from
the
ribbed
carcass,
shortly
after
the
carcass
is
graded
at
24-
to
96-h
postmor-
tem,
requires
that
simulated
retail
display
is
initiated
at
a
time
much
earlier
postmortem
than
most
retail
steaks.
Thus,
one
of
our
objectives
was
to
assess
color
stabil-
ity
measurements
taken
on
a
LM
steak
removed
from
the
carcass
immediately
after
grading
compared
with
those
taken
on
a
steak
removed
from
a
strip
loin
that
had
been
vacuum
packaged
and
aged
until
14
d
postmortem.
Furthermore,
we
assessed
the
color
stability
of
steaks
subjected
to
prolonged
aging
(35
d)
being
placed
in
sim-
ulated
retail
display.
Fourteen
days
of
aging
is
the
most
commonly
used
aging
time
for
meat
tenderness
research
and provides
a
basis
for
comparing
meat
color
research
with
other
meat
quality
studies.
Additionally,
the
35-d
aging
period
represents
a
prolonged
aging
treatment
that
is
relatively
common
in
commercial
practice.
The
least-
squares
means
and
trend
lines
describing
change
in
color
attributes
for
steaks
from
each
of
the
sampling
and
aging
times
evaluated
are
presented
in
Figure
2.
Of
the
color
attributes
evaluated
in
this
study,
only
L*
was
not
affected
(1
3
>
0.05)
by
an
aging
time
x
day
of
display
interaction,
and
lightness
did
not
differ
(1
3
>
0.05)
across
aging
times
(Figure
2A).
Regardless
of
aging
time,
lightness
decreased
through
the
display,
with
the
greatest
decline
occurring
during
the
first
4
d
of
display,
and
very
small
decreases
between
d
4
and
7
d
of
display.
The
greatest
differences
in
color
changes
across
ag-
ing
times
were
detected
in
a*
(Figure
2B).
The
inter-
cept
for
the
equation
describing
the
changes
in
steaks
removed
from
the
carcass
after
grading
was
greater
(P
<
0.05)
than
the
intercepts
for
steaks
aged
for
14
or
35
d
before
being
placed
in
display.
The
linear,
quadrat-
Table
3.
Repeatability
estimates
of
color
traits
of
beef
LM
steaks
in
simulated
retail
display
for
11
d
Day
of
display
Trait'
0
1
4
7
11
L*
0.81
0.85
0.84
0.80
0.80
a*
0.36
0.33
0.89
0.94
0.85
b*
0.58
0.57
0.74
0.75 0.55
Hue
angle
0.80
0.84
0.93
0.97
0.91
Chroma
0.44
0.38
0.83
0.89
0.66
K/S
572
/K/S
525
0.70
0.73
0.85
0.97
0.89
AE
0.23
0.89
0.92
0.82
Myoglobin
0.96
pH
0.85
'AE
=
overall
color
change.
ic,
and
cubic
0-coefficients
were
different
(P
<
0.05)
in
the
3
equations
describing
change
in
a*
values
of
steaks
from
the
3
aging
treatments
evaluated
in
the
present
ex-
periment.
The
trend
lines
for
a*
changes
in
steaks
re-
moved
from
carcasses
after
grading
and
those
aged
for
14
d
before
simulated
retail
display
diverged
after
4
d
of
display,
and
a*
values
were
greater
(P
<
0.05)
in
steaks
removed
from
the
carcass
after
grading
than
those
aged
for
14
d
on
d
7
and
11
of
display;
however,
the
magni-
tudes
of
these
differences
were
not
large.
The
decline
in
a*
values
was
much
more
rapid
in
steaks
aged
for
35
d
than
in
steaks
aged
for
14
d
or
those
obtained
after
grad-
ing
between
d
1
and
7
of
display.
After
7
d,
changes
in
a*
in
steaks
aged
for
35
d
were
small.
The
intercept
values
for
the
equations
describing
b*
did
not
differ
across
aging
times.
The
linear
coefficients
were
similar
(P
>
0.05)
between
the
b*
equations
for
steaks
obtained
after
grading
and
those
aged
for
35
d,
and
both
differed
(P
<
0.05)
from
the
linear
coefficient
of
the
equation
for
steaks
aged
for
14
d.
The
quadratic
coefficients
differed
(P
<
0.05)
across
the
equations
de-
scribing
b*
changes
in
the
3
treatments.
The
cubic
term
of
the
equation
describing
b*
in
steaks
removed
from
the carcass
after
grading
was
not
different
from
0
(P
=
0.34).
The
cubic
coefficient
for
the
equation
describing
changes
in
b*
of
steaks
aged
for
14
d
differed
(P
<
0.05)
from
the
coefficient
for
the
equation
describing
b*
in
steaks
aged
for
35
d.
Compared
with
steaks
collected
from
the
carcasses
after
grading,
b*
values
of
steaks
aged
for
14
d
were
greater
(P
<
0.05)
on
dl
and
4,
and
lower
(P
<
0.05)
on
d
7
of
display.
These
differences
were
small
and
b*
was
not
different
between
steaks
aged
for
14
d
and
those
obtained
after
grading
on
d
11
of
dis-
play.
Compared
with
the
other
2
aging
treatments,
the
decline
in
b*
values
was
much
more
rapid
in
steaks
aged
for
35
d
between
d
1
and
7
of
display,
with
only
small
changes
occurred
in
b*
in
steaks
aged
for
35
d
between
d
7
and
11
of
display.
pH
5.60
5.58
0.005
<0.001
Aged
144
Post-grading
Aged
35d
=44.69
.1.284
4
day
+0.147
.
day"2-0.006"day
.
3
—4
5C/
50
45
411
35
4s
40
)5
au
30
7.
25
20
15
10
5
25
"
1
20
-
15
-
10
5
-
0
3
9
10
11
4
5
6
7
Day
of
display
Aged
144
—Aged
14d
a•
32.47-0.111•7114-0.220`daye2+0.11•May•3
Post-grading
—101t-grading
=
33
24-1.581'day+0.014'day^2-0.001'day
,
3
Aged
35
d
---Aged
3571
a•
•31.77.9.1764%143.0.5138
,
4142-0.058•4145
------------
4
S
6
7
8
9
10
Day
of
display
3602
King
et
al.
35
30
25
C
D
--------
50
40
-
------
-
------
-a_
---
----------------
30
10
Aged
144
—Aged
14d
b•
27.06.0.009•day41.205•day"270
014"day•3
Post-grading
—Post-grading
27.06-0.935
day+0.048
.
71a3
.
2+0.032
day
.
3
Aged
35
41
-
--Aged
35d
b
.
-17
05
0.911`day-0.046"day•244.005
.
day.3
Aged
144
—Aged
1441
ha
=
36.33
+0.400
.
-day
0.06.1•day1
+0.003
.
day3
m
Foss-grading
Past-grading
ha=
35.75+0.065
4149+0.152
.
day"2.0.004
.
day"3
Aged
3511
—.Aged
35
d
ha
=
37.34
--1
662
71ey+0.735
dar2
0.041
0
7104
.
3
20
10
50
45
3
4
5
6
7
8
9
Day
of
display
E
10
11
3
4
5
6
7
Day
of
display
1
40
8
1
10
F
11
40
1
IS
1.00
30
Cs"
0.80
25
-
Si
--------------
.
-----
20
Li
0.60
r
Aged
14d
Aged
140
ag
15
—2ge8
14
4
0414.4
=42.10-
0424•05
-
0
29944y2
.0418
6
4453
—Aged
14
d
mrnb
1.17.
0.1115•day-1:1037/84.2
0
40
Post-grading
Posbgrading
20
—1051-gradingchroma
4334-
1.876'day
0.659`41y
.
2
-
0.003'4143
—Pastgradog
rnrnb
=
1.25
-0.028•414
+11.00.2
.
414.2
Aged
354
0.20
Aged
35
d
---Aged
35
d
chcoma
=41.84
4/675w414
0.432
.
09.2
0.003•day.3
35
d
rnna
1.23-0.0.59
.
444
0.00113Ydar2
0
0.00
1
4
5
6
7
El
9
10
11
2
3
4
5
6
7
0
8
10
11
Day
of
display
Day
of
display
30
Aged
144
—Aged
14
d
81
=
0.05.
2.082"414+
0.169day2
0.015"day1
G
25
Post-grading
—Post-grading
AI
1203
+
2681
.
day
-0.065`day"2
0.0112•710•1
Aged
354
---Aged
15
d
LIE
=
0.03+
2.082
.
day-
0.048
day"2
0.002/day"1
20
64
C
f•
-
15
15
S
E
10
6
4
5
b
1
9
10
11
Day
of
display
Figure
2.
Least
squares
means
and
predicted
trends
with
LM steaks
removed
from
the
carcass
after
grading,
aged
in
vacuum
for
14
d,
or
aged
in
vacuum
for
35
d
before
being
placed
in
simulated
retail
display
for
11
d.
HA
=
hue
angle;
MMB
=
Metmyoglobin
content
(estimated
by
K/S
572
/K/S
525
ratios;
DE
=
AE
(overall
color
change).
Aging
effects
on
beef
color
stability
3603
All
of
the
terms
for
the
cubic
equations
describing
the
changes
in
hue
angle
values
were
similar
(1
3
>
0.05)
between
steaks
aged
for
14
d
before
being
placed
in
sim-
ulated
retail
display
and
those
obtained
from
carcasses
immediately
after
grading
although
the
cubic
term
tend-
ed
(P
=
0.16)
to
be
different
between
these
2
groups
of
steaks
(Figure
2D).
Thus,
hue
angle
was
similar
at
the
beginning
of
display
for
these
2
treatments
and
re-
mained
similar
until
after
7
d
of
display,
after
which
hue
angle
increased
at
a
faster
rate
in
steaks
aged
for
14
d.
Intercepts
were
similar
(P
<
0.05)
between
the
equations
for
steaks
aged
for
14
or
35
d
before
being
placed
in
simulated
retail
display,
but
all
of
the
0-coefficients
dif-
fered
(P
<
0.05)
between
these
2
equations.
Furthermore,
all
of
the
terms
differed
(P
<
0.05)
between
the
equa-
tions
describing
the
changes
in
hue
angle
between
steaks
removed
from
the
carcass
after
grading
and
those
aged
for
35
d
before
simulated
retail
display.
Between
d
4
and
7
of
display,
hue
angle
increased
at
a
much
faster
rate
in
steaks
aged
for
35
d
before
being
placed
in
display
than
in
steaks
aged
for
14
d
or
those
obtained
after
grading.
After
7
d
of
display,
the
further
increases
in
hue
angle
of
steaks
aged
for
35
d
occurred
at
a
slower
rate.
All
parameters
for
the
equations
describing
change
in
color
intensity
(chroma)
of
steaks
removed
from
the
carcasses
post-grading
were
different
(P
<
0.05)
from
those
of
the
equations
describing
chroma
in
steaks
aged
for
14
or
35
d
postmortem
(Figure
2E).
Neither
the
quadratic
nor
the
cubic
term
of
the
equation
describ-
ing
chroma
in
steaks
obtained
after
grading
were
differ-
ent
(P
=
0.24
and
0.40,
respectively)
from
0;
thus,
the
decline
in
chroma
in
these
steaks
can
be
described
as
linear,
whereas
the
decline
in
chroma
during
display
of
steaks
aged
for
14
or
35
d
postmortem
is
best
described
as
cubic.
The
cubic
parameters
were
different
(P
<
0.05)
between
the
equations
for
chroma
in
steaks
aged
for
14
or
35
d,
but
all
other
parameters
were
similar
between
these
2
equations.
Thus,
chroma
was
similar
between
steaks
aged
for
14
or
35
d
at
the
initiation
of
display,
but
chroma
declined
more
rapidly
in
steaks
aged
for
35
d,
particularly
between
d
4
and
7
of
display.
At
the
initiation
of
display,
K/S
572
/K/S
525
inter-
cept
values
were
less
(P
<
0.05)
for
steaks
aged
for
14
d
before
simulated
retail
display
compared
with
those
removed
from
the
carcass
after
grading
and
those
aged
for
35
d
before
being
placed
in
display
(Figure
2F).
The
quadratic
models
fit
the
plots
of
least-squares
means
of
steaks
from
the
post-grading
and
14-d
aged
treatments
well,
but
did
not
appear
to
fit
the
changes
in
the
35-d
steaks.
This
is
likely
because
the
statistical
analysis
was
limited
to
cubic
models
and
the
changes
in
K/S
572
/K/
S
525
of
35
d
aged
steaks
appeared
to
be
quartic
in
nature.
The
regression
model
fit
for
35-d-aged
steaks
was
es-
sentially
linear,
as
the
quadratic
term
was
not
different
from
0
(P
=
0.42).
Nevertheless,
it
is
clear
that
metmyo-
globin
accumulation,
as
evidenced
by
K/S
572
/K/S
525
ratios,
was
more
rapid
in
steaks
aged
for
35
d
relative
to
steaks
aged
for
14
d
or
obtained
after
grading.
The
linear
and
quadratic
terms
of
the
equations
describing
the
trends
associated
with
K/S
572
/K15
525
ratios
of
steaks
aged
for
14
d
or
obtained
post-grading
differed
(P
<
0.05),
although
both
indicate
a
delay
phase
followed
by
an
increasing
rate
of
metmyoglobin
accumulation.
The
trend
for
metmyoglobin
accumulation
in
steaks
removed
from
the
carcass
after
grading
was
similar
to
the
trend
in
steaks
aged
for
14
d,
except
that
metmyoglobin
ac-
cumulation
was
slightly
more
rapid
during
the
first
4
d
of
display,
and slightly
less
rapid
between
d
7
and
11
of
display
in
steaks
removed
from
the
carcass
after
grading.
Ledward
(1985)
reported
that
metmyoglobin
accumula-
tion
followed
the
pattern
of
a
rapid
accumulation
phase,
followed
by
a
slower
phase,
and
then
by
another
rapid
accumulation
phase.
By
definition,
intercepts
were
equal
for
the
equations
describing
overall
color
change
in
the
steaks
from
the
3
aging
treatments
examined
in
the
present
experiment,
and
a
common
linear
term
was
fit
for
each
of
the
3
equa-
tions
(Figure
2G).
Moreover,
neither
the
quadratic
nor
the
cubic
term
of
the
equations
describing
color
change
in
steaks
obtained
from
carcasses
immediately
post-grading
and
those
aged
for
14
d
before
being
placed
in
simulated
retail
display
were
different
from
0
(P
>
0.05).
Thus,
the
linear
increases in
AE
were
very
similar
in
steaks
from
these
2
aging
treatments.
In
contrast,
the
increase
in
AE
in
steaks
aged
for
35
d
before
being
placed
in
simulated
retail
display
was
much
more
rapid
between
1
and
7
of
display;
yet,
between
d
7
and
11,
the
rate
of
overall
color
change
slowed
in
steaks
aged
for
35
d.
The
longer
time
between
cutting
and
initial
color
measurement
is
likely
the
cause
of
differences
in
ini-
tial
values
of
a*,
chroma,
and
K/5
572
/K/S
525
between
steaks
collected
after
grading
and
those
aged
for
14
d
be-
fore
being
placed
in
display.
We
allowed
steaks
that
had
been
aged
before
display
to
bloom
for
2
h
before
color
measurement
to
allow
complete
oxygenation.
However,
Lee
et
al.
(2008)
estimated
asymptotic
values
of
color
attributes
during
blooming
to
be
beyond
those
attained
during
2
h
of
bloom,
indicating
that
complete
oxygen-
ation
may
require
longer
than
2
h.
The
shapes
of
regression
curves
describing
the
change
in
color
attributes
of
these
steaks
during
display
indicate
that
the
prolonged
aging
time
profoundly
af-
fected
the
ability
of
the
muscle
to
maintain
color.
This
is
consistent
with
the
results
reported
by
Hood
(1980),
which
indicate
that
increased
time
postmortem
was
as-
sociated
with
increased
metmyoglobin
accumulation
in
beef
samples
incubated
at
25°C
for
7.5
h.
Liu
et
al.
(1996)
reported
that
increasing
aging
time
of
LM
steaks
3604
King
et
al.
Table
4.
Pearson
correlation
coefficients
for
color
traits
of
steaks
during
display
that
were
removed
from
the
carcass
after
grading
(4
d
postmortem)
or
aged
for
14
or
35
d
postmortem
before
being
placed
in
simu-
lated
retail
display'
Day
L*
a*
b*
Steaks
removed
from
the
carcass
after
grading
to
steaks
aged
for
14
d
d
0
0.70*
0.11
0.13
d
1
0.71*
0.08 0.18
d4
0.77* 0.74* 0.61*
d
7
0.75* 0.88* 0.74*
d
11
0.85* 0.85* 0.65*
Steaks
aged
35
d
to
steaks
aged
14
d
d
0
0.74*
0.12
0.25*
d
1
0.80* 0.30* 0.39*
d4
0.82* 0.89* 0.71*
d
7
0.70* 0.68* 0.25*
d
11
0.81* 0.46*
0.21*
Steaks
removed
from
the
carcass
after
grading
to
steaks
aged
for
35
d
d
0
0.65*
-0.05
0.07
d
1
0.67*
0.11
0.25*
d
4
0.74* 0.75* 0.58*
d
7
0.71* 0.64* 0.28*
d
11
0.76* 0.54*
0.09
*P<
0.05.
1
AE
=
overall
color
change.
K/S
572
/K/S
525
Hue
angle
Chroma
AE
0.73* 0.65*
0.06
0.79* 0.74*
0.05
0.22*
0.84* 0.86* 0.69* 0.82*
0.88* 0.94* 0.83* 0.87*
0.83* 0.88* 0.77* 0.78*
0.46* 0.76*
0.13
0.81* 0.78*
0.30*
0.33*
0.95* 0.93*
0.84*
0.91*
0.73* 0.83*
0.51*
0.69*
0.37* 0.50*
0.27*
0.34*
0.44*
0.68*
-0.05
0.84* 0.78*
0.07
0.35*
0.86* 0.87*
0.68*
0.78*
0.66* 0.77*
0.48*
0.60*
0.52* 0.56*
0.22*
0.36*
from
14
to
28
and
from
28
to
56
d
postmortem
increased
changes
in
a*
and
hue
angle
values,
which
resulted
in
reduced
color
life
of
steaks.
The
results
of
the
present
experiment
were
in
partial
agreement
with
those
of
Lindahl
(2011),
which
reported
that LM
and
semimem-
branosus
steaks
aged
in
vacuum
for
25
d
had
less
sur-
face
metmyoglobin
formation
during
5
d
of
aerobic
dark
storage
than
steaks
of
the
same
muscles
aged
for
5
d
in
vacuum.
However,
Lindahl
(2011)
also
reported
steaks
that
were
not
aged
(2
d
postmortem)
had
greater
surface
metmyoglobin
accumulation
than
steaks
that
were
aged.
Our
primary
aim
in
these
comparisons
was
to
deter-
mine
the
degree
to
which
color
stability
measurements
were
correlated
across
sampling
and
aging
conditions.
It
was
important
to
determine
the
extent
to
which
color
sta-
bility
evaluated
at
1
aging
time
was
indicative
of
the
col-
or
stability
measured
at
another
aging
time.
Correlation
coefficients
comparing
the
values
for
color
attributes
of
steaks
from
each
aging
time
are
presented
in
Table
4.
The
relationships
of
color
stability
measurements
taken
on
steaks
removed
after
grading
to
those
of
steaks
aged
for
various times
before
placement
in
simulated
retail
display
were
of
particular
importance
because
using
such
steaks
would
greatly
increase
the
efficiency
and
cost-effective-
ness
of
future
genomics
and
technology
research
on
color
stability.
When
these
3
aging
times
were
compared,
all
color
attributes
were
highly
correlated,
except
for
a*,
b*,
and
chroma
values
measured
on
d
0
and
d
1
of
display
(Table
4).
During
later
days
of
display,
the
correlation
for
these
and
all
other
traits
increased
as
the
variation
in
these
traits
increased.
This
is
consistent
with
the
changes
in
correlation
of
color
attributes
of
various
beef
muscles
to
LM
color
attributes
during
display
(King
et
al.,
2011b).
The
high
degree
of
correlation
between
color
attributes
of
steaks
aged
for
14
d
before
being
placed
in
simulated
retail
display
and
those
removed
from
the
carcass
after
grading
indicates
that
removing
steaks
from
the
carcass
after
grading
and
placing
them
immediately
into
simulat-
ed
retail
display
will
provide
color
stability
evaluations
that
are
indicative
of
the
color
stability
of
aged
beef.
Color
stability
was
substantially
different
between
steaks
aged
for
14
d
and
those
aged
for
35
d
before
be-
ing
placed
into
simulated
retail
display.
As
described
ear-
lier,
a*
and
chroma
were
not
correlated
on
d
0
of
display
between
steaks
aged
for
14
d
and
those
aged
for
35
d
before
being
placed
in
simulated
retail
display
(Table
4).
However,
both
a*
and
chroma
were
moderately
to
highly
correlated
between
these
ageing
treatments
on
d
1,
4,
7,
and
11
of
display.
Furthermore,
all
other
color
attributes
were
moderately
to
highly
correlated
between
steaks
aged
for
14
d
and
those
aged
for
35
d
before
being
placed
in
simulated
retail
display.
Similarly,
there
were
remark-
ably
strong
relationships
between
steaks
collected
after
grading
and
those
aged
for
35
d
before
being
placed
in
simulated
retail
display.
The
high
degree
of
correlation
among
color
attributes
of
steaks
from
the
investigated
sampling
and
aging
treatments
indicated
that
color
sta-
bility
data
collected
at
any
given
postmortem
aging
time
would
be
indicative
of
color
stability
of
steaks
from
the
same
carcass
aged
for
a
different
amount
of
time.
Aging
effects
on
beef
color
stability
3605
These
results
indicate
that
color
stability
measure-
ments
are
highly
repeatable,
and,
thus,
suitable
for
phenomic
studies
of
this
economically
important
trait.
These
results
also
indicate
that
postmortem
aging
has
profound
impacts
on
retail
color-life
of
beef
products,
but
that
animal-to-animal
variation
is
relatively
consis-
tent
across
aging
times.
Therefore,
intervention
strate-
gies
developed
to
improve
beef
lean
color
stability
at
shorter
aging
time
also
should
be
effective
for
product
lines
using
longer
aging
times.
Furthermore,
steaks
re-
moved
from
the
carcass
after
grading
can
be
used
to
re-
duce
cost
and
increase
throughput
of
studies
to
develop
prediction
technology
and,
at
the
same
time,
produce
re-
sults
that
can
be
applied
to
meat
aged
in
typical
manner.
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