JOURNAL OF FOOD SCIENCE
CHEMISTRY/BIOCHEMISTRY
Lipid Oxidation, Volatiles and Color
Changes of Irradiated Pork Patties as
Affected by Antioxidants
X. Chen, C. Jo, J. I. Lee, and D. U. Ahn
ABSTRACT
Changes were measured in TBARS, color, and volatiles of irradiated (4.5 kGy)
pork patties with antioxidants (sesamol, quercetin, rutin, BHT, and rosemary oleoresin) during 7 days storage at 4 C. Irradiation accelerated lipid oxidation of raw
pork during storage. However, irradiation before cooking did not influence lipid
oxidation of cooked pork during storage. Sesamol, quercetin, and BHT were effective in both irradiated raw and cooked pork during 7-days storage. Rosemary
oleoresin and rutin were effective only in irradiated raw pork for 3 days. Hexanal,
propanal and higher boiling components were well correlated (P 0.01) with TBARS
in cooked pork. Generation of volatiles was reduced by sesamol and quercetin,
but the effects of antioxidants on color changes of raw pork patties were minor
and inconsistent.
Key Words: natural antioxidants, lipid oxidation, volatiles, irradiation, pork
8
,
INTRODUCTION
A MAJOR CONCERN ASSOCIATED WITH MEAT
IRRADIATION IS LOWered meat quality, which
is related to free radical reactions and off-odor
production. Irradiation, at 1.5- to 10-kGy
doses, has increased TBARS in turkey meat
and fish muscles (Al-Kahtani et al., 1996;
Hampson et al., 1996; Ahn et al., 1997). Peroxide values of ground beef and pork increased greatly as a function of irradiation
dose (Groninger et al., 1956; Lefebvre et al.
1994). Oxygen had a catalytic effect on
irradiation-induced lipid oxidation (Lambert
et al., 1992; Thayer et al., 1993).
Initiators of lipid oxidation in irradiated meat
are considered to be hydroxyl radicals generated by the interaction of ionizing energy with
water molecules in muscle tissues or in meat
products (Thakur and Singh, 1994). Oxygen
dissolved in meat tissue or surrounding the
product is subject to activation by ionizing radiation (Diehl, 1995) and may generate reactive oxygen species. Hydroxyl radicals and
other reactive oxygen species interact with lipids in meat and form lipid hydroperoxides.
Subsequent breakdown of such hydroperoxides generates volatiles, which may partially
contribute to the odor of irradiated meat. Free
radicals may interact with heme pigments in
meat and change meat color. Meat contains
endogenous antioxidative enzymes and compounds such as superoxide dismutase, catalase, peroxidases, glutathione, cystine, and vi-
tamin E. However, vitamin E in turkey meat
was partially destroyed by irradiation (Lakritz
et al., 1995; Ahn et al., 1997). Therefore, the
endogenous antioxidant system in meat may
be degraded during irradiation and may not be
strong enough to inhibit lipid oxidation induced
by irradiation. The addition of antioxidants to
meat may retard lipid oxidation and increase
shelf life of treated meat products.
The antioxidant effects of flavonoids in
palm oil (Das and Pereira, 1990) and ground
fish (Ramanathan and Das, 1992) have been
reported. Little information is available on the
effects of phenolic antioxidants in irradiated
raw meat and further processed meat products is available. Three phenolic antioxidants,
quercetin, rutin and sesamol, were selected
on the basis of their antioxidant effects in oil
emulsion (Chen and Ahn, unpublished data).
Two commercially available antioxidants,
rosemary oleoresin and butylated hydroxytoluene (BHT), are also known to be effective.
The objectives of our research were to
determine the effects of sesamol, quercetin,
rutin, rosemary oleoresin, and BHT on: (1)
the storage stability of irradiated cooked pork
patties, measured as TBARS and volatiles;
and (2) the storage stability of irradiated raw
pork patties, measured as TBARS and color
changes.
MATERIALS & METHODS
The authors are affiliated with the Dept. of Animal
Science, Iowa State Univ., Ames, IA 50011-3150.
Direct inquiries to Dr. D. U. Ahn.
16
were purchased from Aldrich (Milwaukee,
WI). Rosemary oleoresin was obtained from
Ecom Manufacturing Corporation (Scarborough, Ont., Canada). Pork ham and backfat
were obtained from a local meat packing company, separately ground and mixed to a final
fat content of 13%. Antioxidants (21 mg each)
quercetin, rutin, sesamol, BHT, and rosemary
oleoresin (42 mg) were dissolved in 8 mL
ethanol (0.5% of the weight of meat patties)
and mixed with ground pork to a final concentration of 0.01% for sesamol, quercetin,
rutin and BHT, and 0.02% for rosemary oleoresin, based on fat content. Ethanol (8 mL)
was added to the control.
Pork patties were packaged in
oxygen-impermeable bags (Koch, Kansas
City, MO) and stored at 48C overnight to minimize quality changes during storage before
irradiation. Next morning, raw pork patties
were aerobic-packaged and irradiated with
accelerated electrons using a Linear Accelerator (Circe IIIR, Thomson CSF Linac,
Saint-Aubin, France) to a dose of 0 or 4.5kGy
(dose rate 99.6 kGy/min). Three hours after
irradiation, half the irradiated and
non-irradiated pork patties were cooked in an
electric oven (1778C) to internal temperature
78°C, and the other half were used for the
raw pork study. All pork patties were stored
under aerobic condition for 7 days at 48C.
Lipid oxidation of both raw and cooked pork
patties during storage was determined by the
thiobarbituric acid reactive substances
(TBARS) method (Ahn et al., 1998a). Volatiles of cooked pork patties were analyzed by
the method of Ahn et al. (1997).
Color measurement
Color measurements were made on the
surface of raw pork patties with a Labscan
spectrophotometer (Hunter Associated Labs.,
Inc. Reston, VA) that had been calibrated
against white and black reference tiles. Hunter L- (lightness), a- (redness), and b- (yellowness) values were obtained using a setting of D65 (daylight, 65-degree light angle).
An average value from two random locations
on each sample surface was used for statistical analysis.
Sample preparation
Statistical analysis
Sesamol and BHT were purchased from
Sigma (St. Louis, MO). Quercetin and rutin
The experiment was designed to determine
the effects of irradiation and different antiox-
JOURNAL OF FOOD SCIENCE—Volume 64, No. 1, 1999
© 1999 Institute of Food Technologists
idants on lipid oxidation, volatiles content and
color changes in pork samples during 7-days
storage. Data were analyzed using SAS software (SAS Institute, Inc., 1989), and the
Student-Newman-Keuls multiple range test
was used to compare differences among
means. Mean values and standard errors of
means (SEM) were reported. Significance
was defined at P,0.05.
RESULTS & DISCUSSION
TBARS Values
Lipid oxidation of raw pork during storage was affected by irradiation and antioxidants (Table 1). Irradiation increased
(P,0.05) lipid oxidation of raw pork at all
storage times. Effects of antioxidants were
more notable in irradiated raw pork than in
nonirradiated. Sesamol was a strong antioxidant and reduced TBARS of irradiated pork
by 30%, 66%, and 41% of the control value at
0, 3, and 7 days storage, respectively. Quercetin also inhibited lipid oxidation of irradiated pork by 26%, 62%, and 39% of the control
value at 0, 3, and 7 days storage, respectively.
Rutin, rosemary oleoresin, and BHT had antioxidant effects at Day 3 and reduced TBARS
by 26%, 40%, and 53% of the control, respectively. At Day 7, however, rutin and rosemary oleoresin had no antioxidant effects on
irradiated raw pork patties.
TBARS values of cooked pork patties
stored at 48C for 7 days (Table 2) showed
that irradiation prior to cooking did not increase TBARS of cooked pork during storage, and the use of antioxidants reduced lipid oxidation in both irradiated and
non-irradiated cooked pork. As in raw pork,
sesamol was one of the most effective antioxidants in cooked pork, reducing TBARS
of irradiated and nonirradiated pork by 28%
to 40% below control values during the 7-day
storage. Quercetin and BHT were effective
in inhibiting lipid oxidation of non-irradiated
pork at Day 0 only, but were as effective as
sesamol for irradiated pork at all storage
times. No antioxidant activities (P<0.05) of
rutin and rosemary oleoresin were observed
in either irradiated or non-irradiated cooked
pork during storage.
In general, ground raw pork was very susceptible to lipid oxidation, especially when
irradiated and stored in presence of oxygen.
Factors such as irradiation in presence of oxygen, iron contamination, and disintegration
of tissue structures by grinding may have contributed to the susceptibility of ground raw
pork to lipid oxidation. Groninger et al. (1956)
reported that peroxide values of ground pork
and beef increased with increasing irradiation
doses, and peroxide values were .40 (considered rancid), when ground pork was irradiated with 0.3 3 106 rep (ca. 3 kGy). Lefebvre et al. (1994) had reported that peroxide
values of irradiated ground beef (1 to 5 kGy)
increased during 15 days storage at 48C. Ahn
Table 1—TBARS of irradiated (IR) and nonirradiated raw pork patties
treated with different antioxidants during storage at 4°Ce
Day 0
Antioxidat
Control
IR
Day 3
SEM
Control
IR
Day 7
SEM
Control
IR
SEM
(mg MDA/kg meat)
Control
0.01
BHT
RO
Sesamol
Rutin
Quercetin
Mean
SEM
0.18y
0.27ax
0.01
0.16y
0.47ax
0.04
0.31y
0.51bcx
0.19
0.18
0.18
0.16y
0.18
0.18
0.02
0.26ab
0.20ab
0.19b
0.21abx
0.20ab
0.22
0.02
0.02
0.01
0.02
0.01
0.02
0.12y
0.12
0.13
0.14y
0.14
0.14
0.01
0.22cx
0.28bcx
0.16c
0.35bx
0.18c
0.28
0.03
0.01
0.02
0.01
0.03
0.01
0.24y
0.25y
0.23y
0.23y
0.28
0.26
0.02
0.46cdx
0.69ax
0.30dx
0.64abx
0.31d
0.49
0.05
0.02
0.03
0.01
0.05
0.01
a-dDifferent letters within a column are significantly different (P < 0.05).
eSamples were analyzed 3h after irradiation at 4.5 kGy (avg). n = 4. Abbreviations: RO = rosemary oleoresin, BHT = butylated
hydroxyanisole, MDA = malondialdehyde. SEM = standard error of the mean.
x,yDiffferent letters across a row and within the same storage period are significantly different (P<0.05).
Table 2—TBARS of irradiated (IR) and nonirradiated cooked pork patties treated with different antioxidants during storage at 4°Ce
Day 0
Antioxidat
Control
IR
Day 3
SEM
Control
IR
Day 7
SEM
Control
IR
SEM
(mg MDA/kg meat)
Control
BHT
RO
Sesamol
Rutin
Quercetin
Mean
SEM
1.23a
0.96b
1.08ab
0.74c
1.09aby
0.84bc
0.99
0.88
1.14b
0.95c
1.26ab
0.83c
1.39ax
0.93c
1.08
0.06
0.13
0.04
0.05
0.04
0.05
0.06
4.76a
4.25bx
4.31b
3.17c
5.32a
4.95abx
4.46
0.20
4.55ab
3.50cdy
4.32ab
3.12d
5.02a
4.10bcy
4.10
0.22
0.35
0.20
0.32
0.08
0.18
0.22
6.94a
6.20ax
6.49a
4.62bx
6.85a
6.13ax
6.20
0.25
6.48ab
4.91dy
5.92bc
3.90ey
6.75a
5.44cdy
5.57
0.21
0.37
0.09
0.26
0.09
0.27
0.20
a-dDifferent letters within a column are significantly different (P<0.05).
eSamples were cooked 3h after irradiation at 4.5 kGy (avg), and the cooked samples were analyzed 1h after cooking (n = 4).
Abbreviations: RO = rosemary oleoresin, BHT = butylated hydroxyanisole, MDA = malondialdehyde. SEM = standard error of
the mean.
x,yDiffferent letters across a row and within the same storage period are significantly different (P<0.05).
et al. (1997, 1998b) reported that irradiation
of ground, raw, turkey meat and pork meat, at
doses of 2.5 kGy and 4.5 kGy, respectively,
increased TBARS under aerobic conditions.
Unlike in raw meat, irradiation did not increase TBARS of cooked meat during storage (Table 2). In cooked pork patties, development of lipid oxidation was very rapid.
Cooking not only disrupts membrane structures and destroys the endogenous antioxidant system but also facilitates release of iron
from carrier proteins or storage protein. Therefore, compared with cooking, irradiation prior to cooking may not cause much increase in
lipid oxidation of cooked meat (Table 2). Similarly, prior irradiation, under aerobic conditions and at 4.5 kGy, did not have any effect
on lipid oxidation of cooked pork patties during 7-days storage in aerobic bags (Ahn et al.,
1998b).
In raw meat, no difference in antioxidant
activity was found between BHT, sesamol, or
quercetin. In cooked pork (Table 2), however, antioxidant activity of sesamol was more
effective than that of BHT, and quercetin was
comparable to BHT after 7 days storage. Sesamol is an antioxidant component of sesame
oil which has well known resistance to oxidative rancidity (Kikugawa et al., 1983). Quercetin has very high antioxidant activity
(Rice-Evans et al., 1996) and acts as an iron
chelator (Morel et al., 1993). Sesamol and
quercetin may donate hydrogens to free radicals, and may form stable radicals as well because of their ring structures (Nakagawa et
al., 1994; Bors et al., 1990). Sesamol and
quercetin retained their antioxidant activities
after irradiation and retarded the lipid oxidation of raw pork patties during the 7-days
storage, and also were relatively stable and
active in cooked pork.
Volatiles
Peaks from hexanal (Table 3), propanal
(Table 4), and higher boiling components (Table 5) (1-butanol, 1-pentanol, and nonanal)
were measured as indicators of changes in
volatiles from cooked pork during storage.
Volatiles increased rapidly during the first three
days of storage.
Irradiation increased the amount of propanal in cooked pork at Day 0 and Day 3. In
nonirradiated pork (Table 3), all antioxidants
reduced propanal content, but sesamol was
the most effective antioxidant tested. In irradiated pork patties, sesamol, quercetin, and
BHT reduced generation of propanal during
storage. However, rosemary oleoresin had no
effect on propanal generation during the 7-day
storage period and rutin was effective in reducing propanal content in non-irradiated pork
at Day 3 only. Also, sesamol was one of the
Volume 64, No. 1, 1999 —JOURNAL OF FOOD SCIENCE
17
Antioxidant Effects on Irradiated Pork . . .
most effective antioxidant for reducing propanal content in irradiated pork.
Changes of volatiles in cooked pork during storage under aerobic conditions may be
ascribed partially to lipid oxidation. Hexanal
has been followed to determine the degree of
lipid oxidation (Dupuy et al., 1987). Ahn et
al. (1998a) reported that hexanal and propanal were well correlated with TBARS (r2 5
0.71 and 0.70, respectively). High correlations between TBARS and hexanal (r 2 =
0.69), propanal (r2 5 0.48) and higher boiling volatiles (r2 5 0.82) were confirmed in
our results. Little difference in hexanal production for irradiated and nonirradiated cooked
pork patties was observed during the 7-days
storage (Table 4). This was consistent with
TBARS values and indicated irradiation before cooking did not accelerate lipid oxidation
of cooked meat during storage. In nonirradiated pork (Table 4), sesamol reduced the generation of hexanal at Day 0 and Day 7, quercetin at Day 0, and rutin at Day 7. In irradiated pork (Table 4), quercetin reduced the generation of hexanal at Day 3.
Irradiation decreased amounts of higher
boiling components in cooked pork at Day 3
and Day 7 (Table 5). Due to further degradation of lipids, the higher boiling components
were more obvious in cooked pork stored
for longer times (e.g., 7 days). In nonirradiated pork (Table 5), effects of antioxidants
were not significant except that sesamol and
rutin reduced amounts of higher the boiling
components at Day 7. However, in irradiated pork (Table 5), all antioxidants except
rosemary oleoresin reduced the higher boiling components at Day 7. Again, sesamol
was the most effective compound for inhibiting generation of higher boiling components at Day 3 and as effective as BHT, rutin
and quercetin at Day 7.
It has been reported that irradiated meat
had a characteristic off-odor (Lynch et al.,
1991; Hashim et al., 1995). Merritt (1966)
suggested that irradiation effects on the protein and lipid molecules in meat could produce off-odor volatiles. However, it is still
unclear which volatile compounds are responsible for such off-odors in irradiated meat and
how the volatiles are generated. Given our
evidence that sesamol and quercetin were effective in reducing amounts of volatiles from
irradiated pork, they may be helpful in reducing off-odor production in irradiated meat.
However, sensory tests are needed to confirm the effectiveness of these antioxidants to
reduce irradiation-induced off-odors.
Color
Data on lightness of raw pork during storage (Table 6) showed irradiation did not affect L-values of raw pork during the 7-days
storage. Quercetin increased L-values of all
raw pork patties because of the bright yellow
color of quercetin. The effects of other antioxidants on L-values of raw pork during stor-
18
Table 3—Propanal content of irradiated (IR) and nonirradiated cooked
pork patties treated with different antioxidants during storage at 4°Cf
Day 0
Antioxidat
Control
IR
Day 3
SEM
Control
IR
Peak area (pA
Control
BHT
RO
Sesamol
Rutin
Quercetin
Mean
SEM
18.7ax
12.7abx
14.2abx
9.7bx
13.8abx
9.9bx
13.2
1.6
28.9ay
23.1aby
28.6ay
18.0by
28.8ay
22.4aby
25.0
1.9
0.9
2.2
1.9
2.1
1.7
1.3
35.5ax
33.6ab
25.6bx
19.7cx
28.7ab
34.0abx
29.5
2.2
Day 7
SEM
Control
IR
SEM
2.6
2.3
1.7
1.0
2.1
0.8
42.7a
35.4by
30.2cx
14.1ex
23.4dx
36.4b
30.4
1.1
39.9a
26.4bcx
41.7ay
22.1cy
41.6ay
31.7b
33.9
2.2
1.8
2.1
1.2
1.9
1.2
2.0
3 sec)
47.2ay
28.9c
43.5ay
28.7cy
36.7by
38.9by
37.3
1.4
a-eDifferent letters within a column are significantly different (P<0.05).
f Samples were irradiated either at 0 or 4.5 kGy (abg). n=4. Abbreviations: RO = rosemary oleoresin, BHT = butylated
hydroxyanisole, SEM = standard error of the mean.
x,yDiffferent letters across a row and within the same storage period are significantly different (P < 0.05).
Table 4—Hexanal content of irradiated and nonirradiated cooked pork
patties treated with different antioxidants during storage at 4°Ce
Day 0
Antioxidat
Control
IR
Day 3
SEM
Control
IR
Peak area (pA
Control
BHT
RO
Sesamol
Rutin
Quercetin
Mean
SEM
150a
113
119ab
73b
109ab
72b
106
16
145ab
136ab
147ab
83b
155a
93ab
126
16
9
17
23
16
16
8
282
300
262
224
227
233y
255
17
Day 7
SEM
Control
15
22
10
8
13
8
280b
332a
275b
215c
219c
258bcy
263
13
3 sec)
244abc
231abc
254a
208cd
219abc
189dx
224
8
IR
SEM
240ab
257ab
266a
222ab
248ab
204bx
240
13
12
22
6
13
10
9
a-dDifferent letters within a column are significantly different (P < 0.05).
e Samples were irradiated either at 0 or 4.5 kGy (avg). n = 4..Abbreviations: RO = rosemary oleoresin, BHT = butylated
hydroxyanisole, SEM = standard error of the mean.
x,yDiffferent letters across a row and within the same storage period are significantly different (P<0.05).
Table 5— Content of higher boiling components (1-butanol, 1-pentanol,
and nonanal) of irradiated (IR) and nonirradiated cooked pork patties
treated with different antioxidants during storage at 4°Cd
Day 0
Antioxidat
Control
IR
Day 3
SEM
Control
IR
Peak area (pA
Control
BHT
RO
Sesamol
Rutin
Quercetin
Mean
SEM
11.6
9.9
8.9
7.0
8.5
6.7
8.8
1.24
11.2
9.8
11.6
8.0
12.2
8.9
10.3
1.04
0.5
1.0
1.4
1.2
1.1
1.0
25.4
23.9y
23.4
20.8y
22.2
22.2y
23.0
1.78
Day 7
SEM
Control
1.3
1.8
1.7
0.8
1.5
0.6
27.7ay
27.2ay
25.7ay
20.4by
21.8b
26.0ay
24.8
0.95
3 sec)
21.9a
17.0bx
21.5a
14.1cx
18.5b
17.9bx
18.5
0.69
IR
22.8ax
19.1abx
22.1ax
16.9bx
20.6ab
18.9abx
20.1
1.19
SEM
1.0
1.6
0.8
1.0
0.8
1.2
a-cDifferent letters within a column are significantly different (P<0.05).
d Samples were irradiated either at 0 or 4.5 kGy (avg). n=4. Abbreviations: RO=rosemaryu oleoresin; BHT=butylated
hydroxyanisole; SEM=standard error of the mean.\
x,yDifferent letters across a row and within the same storage period are significantly different (P<0.05).
Table 6—Color L-values (lightness) of irradiated (IR) and nonirradiated raw pork patties treated with different antioxidants during storage at 4°Cd
Day 0
Antioxidat
Control
Control
BHT
RO
Sesamol
Rutin
Quercetin
Mean
SEM
55.42b
55.51b
56.32a
56.00ab
56.52ay
56.85a
56.10
0,.22
IR
55.14 c
55.02 c
55.87b
55.52bc
55.81bx
56.44a
55.63
0.15
Day 3
SEM
0.15
0.23
0.18
0.20
0.13
0.19
Control
56.71b
56.25b
57.09ab
55.99b
56.55b
57.96a
56.76
0.30
IR
56.27b
56.43b
56.05b
55.91b
56.86ab
57.31a
56.47
0.22
Day 7
SEM
0.21
0.24
0.39
0.22
0.26
0.22
Control
55.36b
56.04a
55.32b
55.96a
56.17a
56.37a
55.87
0.16
IR
SEM
55.30b
56.33a
55.71b
55.79b
56.52a
56.67a
56.05
0.17
a-cDifferent letters within a column are significantly different (P<0.05)
d Samples were measured 2h after irradiation at 4.5 kGy (avg). n = 4. Abbreviations: RO = rosemary oleoresin, BHT =
butylated hydroxyanisole, SEM = standard error of the mean.
x,yDiffferent letters across a row and within the same storage period are significantly different (P < 0.05).
JOURNAL OF FOOD SCIENCE—Volume 64, No. 1, 1999
0.17
0.23
0.17
0.09
0.15
0.14
age were not consistent. Irradiated patties had
greater a-values (redness) than did
non-irradiated at storage Day 7. Effects of
antioxidants on redness of both irradiated and
non-irradiated pork during storage were marginal and inconsistent (Table 7).
At storage Day 0 and Day 3, irradiated
patties had lower yellowness than did
non-irradiated. However, yellowness of raw
pork during storage was not affected by antioxidants. However, raw pork with quercetin
had the highest b-values at all storage times,
probably because of the bright yellow color
of quercetin (Table 8). Color changes of irradiated raw meat have been reported (Lebepe
et al., 1990; Lescano et al., 1991; Fu et al.,
1995; Ahn et al., 1998b). However, results
have not been consistent, mainly because of
differences in species, irradiation dose, and
packaging conditions. When small amounts
of antioxidant are used, effects on color change
should be minor.
CONCLUSION
ANTIOXIDANTS FROM NATURAL SOURCES
REDUCED LIPID OXIDAtion and volatiles production in irradiated raw and cooked pork during storage. The relative stability of such antioxidants in meat during irradiation and cooking could increase their effectiveness and potential use in food products in the future.
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Table 7— Color a-values (redness) of irradiated (IR) and nonirradiated
raw pork patties treated with different antioxidants during storage at
4°Cd
Day 0
Antioxidat
Control
BHT
RO
Sesamol
Rutin
Quercetin
Mean
SEM
Control
7.21b
5.97cx
8.02ay
8.01ay
6.99b
8.05ay
7.37
0.17
IR
7.43a
7.30ay
6.55abx
6.36bx
7.00ab
6.72abx
6.89
0.22
Day 3
SEM
0.19
0.31
0.19
0.16
0.14
0.14
Control
5.89bx
7.95a
6.72ab
7.69a
6.58ab
7.20ab
7.01
0.34
IR
6.80by
7.55ab
7.67ab
8.11a
6.99b
7.34ab
7.41
0.26
Day 7
SEM
0.21
0.23
0.45
0.31
0.23
0.34
Control
4.52bx
5.49bx
7.46ax
6.64ax
7.10a
5.47bx
6.11
0.28
IR
SEM
7.71abcy
7.76abcy
8.25ay
8.03aby
7.45bc
7.19bcy
7.73
0.17
0.13
0.23
0.18
0.15
0.29
0.35
a-cDifferent letters within a column are significantly different (P < 0.05).
dSamples were measured 2h after irradiation at 4.5 kGy (avg). n = 4. Abbreviations: RO = rosemary oleoresin, BHT =
butylated hydroxyanisole, SEM = standard error of the mean.
x,yDiffferent letters across a row and within the same storage period are significantly different (P<0.05).
Table 8— Color b-values (yellowness) of irradiated (IR) and nonirradiated raw pork patties treated with different antioxidants during storage at 4°Cd
Day 0
Antioxidat
Control
IR
Control
BHT
RO
Sesamol
Rutin
Quercet
Mean
SEM
13.82by
13.71by
14.00by
13.94by
13.74by
14.40ay
13.94
0.08
13.16x
13.02x
13.20x
13.12x
13.13x
13.18x
13.13
0.08
Day 3
SEM
0.08
0.09
0.11
0.09
0.06
0.06
Control
IR
13.64y
13.97y
13.83y
14.11y
13.88y
14.05y
13.91
0.12
13.02bx
13.30bx
12.98bx
13.24bx
13.11bx
13.61ax
13.21
0.09
Day 7
SEM
0.07
0.12
0.12
0.09
0.09
0.13
Control
13.22b
13.58aby
13.58aby
13.76aby
13.69aby
13.90ay
13.47
0.12
IR
SEM
13.22
13.07x
13.07x
13.26x
12.85x
13.28x
13.13
0.10
0.10
0.11
0.13
0.10
0.1
0.1
a,bDifferent letters within a column are significantly different (P < 0.05).
cSamples were measured 2h after irradiation at 4.5 kGy (avg). n = 4. .Abbreviations: RO = rosemary oleoresin, BHT =
butylated hydroxyanisole, SEM = standard error of the mean.
x,yDiffferent letters across a row and within the same storage period are significantly different (P< 0.05).
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Ms received 5/9/98; revised 7/30/98; accepted 8/6/98.
Journal Paper No. J-17851 of the Iowa Agriculture and Home
Economics Experiment Station, Ames, Iowa, Project No. 3322,
and supported by Hatch Act.
Volume 64, No. 1, 1999 —JOURNAL OF FOOD SCIENCE
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