PROCESSING AND PRODUCTS
Volatiles, Color, and Lipid Oxidation of Broiler Breast Fillets Irradiated
Before and After Cooking1
M. Du, S. J. Hur, K. C. Nam, H. Ismail, and D. U. Ahn2
Department of Animal Science, Iowa State University, Ames, Iowa 50011-3150
ABSTRACT Chicken breast fillets were equally divided
into three groups. One group was vacuum packaged,
cooked in a water bath (cooked-in-bag) at 82 C for 25
min, and then irradiated at 0 or 3 kGy with a linear
accelerator (V-C-I). The other two groups were irradiated
at 0 or 3.0 kGy in vacuum packaging (V-I-C) or aerobic
packaging (A-I-C). After 3 d of storage at 4 C, the irradiated meats were cooked in a water bath (cooked-in-bag)
at 82 C for 25 min. After being cooked, meats were repackaged under vacuum and stored at 4 C. Breast fillets were
analyzed at 0 and 21 d after cooking and analyzed for
lipid oxidation, color, and volatiles.
Irradiation accelerated lipid oxidation of breast fillets.
Three days of storage of raw meat in aerobic conditions
after irradiation had only minor influences on lipid oxidation after cooking. However, irradiation had a significant
effect on the volatile production in meat. Dimethyl disulfide, related to irradiation odor, was significantly higher
in irradiated fillets than in nonirradiated fillets for V-CI and V-I-C, whereas it was only slightly higher for A-IC. Other volatiles, such as 3-methyl butanal and 2-methyl
butanal, were also produced in significant amounts after
irradiation, especially in V-C-I and V-I-C. These results
showed that irradiating cooked meat induced slightly
more changes in volatiles than irradiating raw meat and
then cooking. The amount of dimethyl disulfide between
irradiated and nonirradiated samples for A-I-C was not
different, because the dimethyl disulfide produced by
irradiation disappeared during the 3 d in aerobic storage
before cooking. Color a* value of irradiated fillets was
higher than that of nonirradiated fillets. Irradiation also
induced color L* and b* value changes. After 3 d of aerobic
storage after irradiation of raw meat, the influence of
irradiation on color after cooking was reduced. No significant lipid oxidation occurred during storage as shown
by the low values for TBA-reactive substances.
(Key words: volatile, cook, breast meat, oxidation, irradiation)
2001 Poultry Science 80:1748–1753
INTRODUCTION
Irradiation is one of the most efficient methods available
for ensuring microbiological food safety (Rajkowski and
Thayer, 2000). However, irradiation increases lipid oxidation and forms a characteristic off-odor in meats (Ahn
et al., 1998; Jo and Ahn, 2000). The off-odor induced by
irradiation is characterized as sweet, barbecued corn-like,
and is closely related to the sulfur compounds formed
during irradiation (Jo and Ahn, 2000). There are many
reports on the effect of irradiation on volatile, lipid oxidation, and color of raw meat (Luchsinger et al., 1996; Jo et
al., 1999). Few published reports are available on the volatiles of cooked meat irradiated before or after cooking.
Clearly, irradiation of meat before or after cooking would
2001 Poultry Science Association, Inc.
Received for publication February 2, 2001.
Accepted for publication August 24, 2001.
1
Journal Paper Number J-19198 of the Iowa Agriculture and Home
Economics Experiment Station, Ames, IA 50011-3150; Project No. 6504.
2
To whom correspondence should be addressed: duahn@iastate.edu.
influence the oxidation and volatiles formation in meat.
Cooked meat would be more sensitive to irradiation due
to denatured muscle proteins and damaged membrane
structure. On the other hand, the availability of oxygen
during irradiation will also make a significant difference
in oxidative change and volatile production in meat. Thus,
it is important to assess the influence of packaging at the
time of irradiation on volatiles and lipid oxidation of meat.
Irradiation induces color change in meat (Nanke et al.,
1998). Many reports have suggested that the redness color
(a* value) increased after irradiation (Luchsinger et al.,
1996; Nanke et al., 1998; Du et al., 2000; Millar et al., 2000).
Because consumers may consider the redness of cooked
meat, especially that of white meat, as undercooked, it is
important to have a method to prevent or reduce such
color change after irradiation.
The objective of this study was to assess the influence
of meat condition, raw or cooked, vacuum or aerobically
Abbreviation Key: GC = gas chromatograph; MS = mass spectrometry; TBA/TCA = thiobarbituric acid/trichloroacetic acid; TBARS = 2thiobarbituric acid reactive substances; V-C-I = vacuum packaged,
cooked, and then irradiated; V-I-C = vacuum packaged, irradiated, and
then cooked; A-I-C = aerobic packaged, irradiated, and then cooked.
1748
QUALITY OF BROILER BREAST FILLETS IRRADIATED BEFORE AND AFTER COOKING
1749
and sampled again at 21 d of storage at 4 C, and analyzed
for 2-thiobarbituric acid reactive substances (TBARS),
Hunter color, and volatiles.
Volatile analysis
FIGURE 1. Preparation of cooked chicken breast fillets in different
irradiation conditions. 1V-I-C = raw meat was irradiated and stored in
vacuum packaging, and then cooked. 2A-I-C = raw meat was irradiated
and stored in aerobic packaging, and then cooked. 3V-C-I = raw meat was
cooked in vacuum packaging, and the cooked meat was then irradiated.
packaged, at the time of irradiation on the volatiles, color,
and lipid oxidation of cooked breast fillets.
MATERIALS AND METHODS
A purge-and-trap apparatus connected to a gas chromatograph3 (GC) was used to analyze the volatiles from breast
fillets. A Precept II and Purge-and-Trap Concentrator 30004
were used to trap volatiles, and GC mass spectrometry
(MS) was used to identify and quantify the volatile compounds. One gram of sliced meat was placed in a sample
vial (40 mL), and then one pack of oxygen absorber5 was
added (Ageless type Z-100). The vials were flushed with
helium gas (99.999%) for 5 s at 40 psi and capped tightly.
Vials were placed in a refrigerated (4 C) sample tray. The
maximum holding time before volatile analysis was less
than 10 h to minimize oxidative changes during the sample
holding period (Ahn et al., 1999).
The meat sample was purged with helium gas (40 mL/
min) for 15 min. Volatiles were trapped at 20 C using a
Tenax/Silica gel/Charcoal column4 and desorbed for 2
min at 220 C. The desorbed volatiles were concentrated
at -100 C using a cryofocusing unit, and then thermally
desorbed, and injected (30 s) into a capillary GC column
by increasing the temperature to 220 C. Ramped oven
temperature was used. The initial oven temperature was
0 C and was held for 2.50 min. Then the oven temperature
was increased to 10 C at 5 C/min, to 45 C at 10 C/min,
to 110 C at 20 C/min, to 210 C at 10 C/min, and held for
0.25 min. The column pressure was 20.5 psi. A mass selective detector (HP 5973)3 was used to identify and quantify
volatile components. The ionization potential of the MS
was 70 eV, and scan range was 18.1 to 350. Identification
of volatiles was achieved by comparing mass spectral data
of samples with those of the Wiley Library3 and also with
the standards when available. The area of each peak was
integrated by using ChemStation software,3 and total ion
counts × 104 were reported as an indicator of volatiles
generated from meat samples.
Sample Preparation
TBARS Analysis
Breast fillets were divided into three groups. Group 1
(V-C-I) was cooked in a water bath at 82 C for 25 min,
vacuum packaged, and then irradiated at 0 or 3 kGy with
a linear accelerator. The other two groups were vacuum
packaged (V-I-C) or aerobically packaged (A-I-C) directly
without cooking, and then irradiated as raw meat at 0 or
3.0 kGy. These two groups were then stored at 4 C for 3
d before cooking in a water bath at 82 C for 25 min in
package, and then changed to vacuum packaging (Figure
1). After cooking, fillets were further stored at 4 C. Breast
fillets were sampled 2 h after cooking at 0 d of storage
3
Hewlett Packard Co., Wilmington, DE 16808-1610.
Tekmar-Dorham, Cincinnati, OH 45249.
5
Mitsubishi Gas Chemical America, Inc., White Plains, NY 10601.
6
Brinkman Instruments, Inc., Westbury, NY 11590-0207.
4
Five grams of meat was weighed into a 50-mL test tube
and homogenized with 15 mL of deionized distilled water
using a Polytron homogenizer (Type PT 10/35)6 for 10 s
at the highest speed. One milliliter of meat homogenate
was transferred to a disposable test tube (3 × 100 mm),
and butylated hydroxyanisole (50 µL, 7.2%) and TBA/
trichloroacetic acid (TCA) (2 mL) were added. The mixture
was vortexed and then incubated in a boiling-water bath
for 15 min to develop color. The sample then was cooled
in cold water for 10 min, vortexed again, and centrifuged
for 15 min at 2,000 × g. The absorbance of the resulting
supernatant solution was determined at 531 nm against a
blank containing 1 mL of deionized distilled water and 2
mL of TBA/TCA solution. The amounts of TBARS were
expressed as milligrams of malondialdehyde per kilogram
of meat.
1750
DU ET AL.
TABLE 1. TBA-reative substance values (mg/kg) of cooked chicken breast fillets at different storage times
0 day
Treatment1
0 kGy
3 kGy
V-C-I
V-I-C
A-I-C
SEM
0.29a,y
0.34a
0.31a,y
0.01
0.36b,x
0.39b
0.46a,x
0.01
21 days
SEM
Malonaldehyde
0.01
0.02
0.01
0 kGy
3 kGy
SEM
(mg/kg)
0.34b,y
0.41a
0.39a,b,y
0.02
0.41b,x
0.40b
0.46a,x
0.02
0.01
0.02
0.02
Means within a column with different superscripts differ significantly (P < 0.05); n = 4.
Means within a row of same storage time with different superscripts differ significantly (P < 0.05); n = 4.
1
V-C-I = raw meat was cooked in vacuum packaging, and the cooked meat was then irradiated; V-I-C = raw
meat was irradiated and stored in vacuum packaging, and then cooked; A-I-C = raw meat was irradiated and
stored in aerobic packaging, and then cooked.
a-c
x,y
Color Measurement
The color of breast fillets was measured using a Hunter
LabScan Colorimeter7 and expressed as color L* (lightness),
a* (redness), and b* (yellowness) values. Fillet surface color
was measured in the packages. In doing this, the same
package materials were used to cover the white standard
plate in order to eliminate the influence of packaging materials on meat color. To measure the internal color of the
breast fillets, they were transversely cut in the center, and
the color of new cutting surface was measured immediately.
Statistical Analysis
The effect of irradiation and condition of meat at irradiation on the volatiles, color, and TBARS of chicken breast
were analyzed statistically by general linear models with
SAS威 software (SAS Institute, 1989). Student-NewmanKeuls’ multiple-range test was used to compare differences
among mean values (P < 0.05). Mean values and SEM were
reported. Tukey grouping analysis compares the differences of irradiated vs. nonirradiated samples and samples
of 0 d of storage vs. 21 d of storage. This analysis was
used to analyze the significance of irradiation and storage
effects on TBARS values, color, and volatiles.
RESULTS AND DISCUSSION
TBARS Values
Table 1 shows the TBARS values of breast fillets. The
overall TBARS values were quite low. Comparison of the
TBARS values of 3 kGy irradiated and nonirradiated samples showed irradiated samples to have slightly higher
TBARS values. Tukey grouping analysis showed that there
was no increase in TBARS values after 21 d of storage
under vacuum packaging, indicating that breast fillets
were stable when oxygen was not available (Katusin-Razem et al., 1992). This result was similar to that with chicken
meat patties (Du et al., 2000). When the TBARS values of
7
Hunter Laboratory, Inc., Reston, VA 22090-5280.
cooked meat fillets irradiated at three different conditions
were compared, A-I-C had significantly higher TBARS
than the other two conditions (V-C-I and V-I-C). The main
reason for the higher TBARS value in A-I-C meat was that
the raw meat irradiated and stored in aerobic conditions
had higher lipid oxidation than that in vacuum packaging.
Color Changes
Different meat conditions at the time of irradiation significantly influenced color (Table 2). When cooked meat
was irradiated under vacuum packaging, a significant increase the color a* value of V-C-I fillets was observed.
V-I-C, in which raw meat was irradiated under vacuum
packaging and then cooked, also had significant increase
in a* value. When raw meat was irradiated in aerobic
conditions and then stored 3 d in aerobic conditions before
cooking (A-I-C), color a* value was not different from
that of the nonirradiated control. This result showed that
irradiation in aerobic conditions and 3 d of storage under
aerobic conditions eliminated the influence of irradiation
on the redness of cooked meat color (surface). Significant
differences in b* and L* values were observed among irradiated and nonirradiated V-C-I and V-I-C fillets but not
for A-I-C. Overall, there was no difference in the surface
color of irradiated and nonirradiated A-I-C samples, but
those of the V-C-I and V-I-C were different.
After 21 d of storage at 4 C, the surface color of meat
was fading, and the color a* value decreased (Table 2).
Even so, the color a* values of V-C-I and V-I-C were higher
than that of the A-I-C. The color a* value of A-I-C was
about the same as the nonirradiated fillets. When the inside
color was analyzed, however, there was still a significant
difference between irradiated and nonirradiated samples
for A-I-C (Table 3). The color a* value of irradiated samples
for A-I-C was higher than that of the nonirradiated samples. This higher value suggested that the effect of irradiation on color could be due to irradiation-induced changes,
which disappeared on the surface of fillets after aerobic
display, but not inside. The redness of irradiated meat
was suggested to be associated with carbon monoxide
production during irradiation (Millar et al., 2000). The
change in reduction potential of meat after irradiation also
might be related to the irradiation-induced color change
QUALITY OF BROILER BREAST FILLETS IRRADIATED BEFORE AND AFTER COOKING
1751
TABLE 2. Color of cooked chicken breast fillets at different storage times
0 day
21 days
Treatment1
0 kGy
3 kGy
SEM
0 kGy
3 kGy
SEM
V-C-I
V-I-C
A-I-C
SEM
9.29a,y
8.92a,y
7.35b
0.20
11.56a,x
10.05b,x
7.40c
0.30
Hunter a* value
0.28
6.89a,y
0.26
6.77a,y
0.23
5.79b
0.14
7.62a,x
7.66a,x
5.98b
0.16
0.16
0.15
0.14
17.85a,y
17.70a
17.68a
0.30
0.26
0.29
0.30
79.54b
82.00a
80.80a,y
0.43
0.43
0.47
0.44
V-C-I
V-I-C
A-I-C
SEM
22.2a,y
21.10b
19.21c
0.37
20.74a,x
20.50a
19.83a
0.45
V-C-I
V-I-C
A-I-C
SEM
80.46b,y
83.37a,y
83.63a
0.42
82.32b,x
85.42a,x
84.01a
0.59
Hunter b* value
0.42
18.82a,x
0.47
17.86b
0.34
17.85b
0.27
Hunter L* value
0.51
79.85b
0.58
81.02b
0.44
82.66a,x
0.46
Means within a column with different superscripts differ significantly (P < 0.05); n = 4.
Means within a row of same storage time with different superscripts differ significantly (P < 0.05); n = 4.
1
V-C-I = raw meat was cooked in vacuum packaging, and the cooked meat was then irradiated; V-I-C = raw
meat was irradiated and stored in vacuum packaging, and then cooked; A-I-C = raw meat was irradiated and
stored in aerobic packaging, and then cooked.
a-c
x,y
(Nam and Ahn, 2001). If the above two factors correspond
to irradiation-induced color change, then these two factors
might be removed on the surface of fillets during aerobic
display by carbon monoxide evaporation and oxidation.
Irradiation effects (red color) in the inside of fillets stored
aerobically, however, partially remained after storage.
aging. Dimethyl disulfide increased significantly by irradiation for V-C-I and V-I-C fillets, and its content in V-C-I was
significantly higher than that of the V-I-C. Other volatiles
related to irradiation, 2-methyl propanal, and 3-methyl
butanal also increased significantly after irradiation. This
result indicated that irradiating raw meat and then cooking
induced less irradiation-related volatiles formation compared with irradiating cooked meat. V-C-I had significantly higher aldehyde contents compared with those of
V-I-C and A-I-C in nonirradiated fillets. The reason is not
quite clear. After irradiation, the aldehyde content in V-IC and A-I-C increased greatly, illustrating that irradiating
raw meat can accelerate the oxidation and influence the
volatiles of cooked meat.
Table 5 shows the volatiles from breast fillets after 21 d
of storage. The content of dimethyl disulfide was reduced
significantly after 21 d of storage. For irradiated fillets of
V-C-I, the content of dimethyl disulfide decreased from
483 × 104 ion counts to 7 × 104. For V-I-C it decreased from
259 × 104 ion counts to 58 × 104 ion counts; for A-I-C, it
decreased from 11 × 104 ion counts to 5 × 104 ion counts.
Volatile Profiles
Table 4 shows the volatiles from breast fillets at 0 d of
storage. Tukey grouping analysis showed that dimethyl
disulfide was significantly higher in the irradiated fillets
from V-C-I and V-I-C than the nonirradiated fillets, but
no difference was found between irradiated and nonirradiated samples from A-I-C. Dimethyl disulfide and other
sulfur compounds are derived from degradation of amino
acids and are suggested to be the major volatiles related
to irradiation odor (Ahn et al., 2000a,b). The absence of a
high level of dimethyl disulfide in irradiated fillets from
A-I-C indicated that the sulfur compound had disappeared
from the raw meat during the 3-d storage in aerobic pack-
TABLE 3. Internal color of cooked chicken breast fillets irradiated under
different conditions and after 21 d of storage
Color a* value
Color b* value
Color L* value
Treatment1
0 kGy
3 kGy
SEM
0 kGy
3 kGy
SEM
0 kGy
3 kGy
SEM
V-C-I
V-I-C
A-I-C
SEM
5.67a,y
5.19b,y
4.58c,y
0.10
8.11a,x
7.57b,x
6.43c,x
0.11
0.08
0.11
0.12
16.32b,x
17.11a,x
16.81a,b
0.17
14.83c,y
16.00b,y
16.74a
0.16
0.17
0.20
0.13
81.83a,b,x
81.44b
82.49a,x
0.28
79.73b,y
80.79a
80.09b,y
0.24
0.29
0.25
0.21
Means within a column with different superscripts differ significantly (P < 0.05); n = 4.
Means within a row of same storage time with different superscripts differ significantly (P < 0.05); n = 4.
1
V-C-I = raw meat was cooked in vacuum packaging, and the cooked meat was then irradiated; V-I-C = raw
meat was irradiated and stored in vacuum packaging, and then cooked; A-I-C = raw meat was irradiated and
stored in aerobic packaging, and then cooked.
a-c
x,y
1752
DU ET AL.
Tukey grouping analysis indicated that there was significant irradiation effect for the dimethyl disulfide content
of V-C-I and V-I-C. The reason for decreasing dimethyl
disulfide content in volatiles was not clear. One possible
reason might be due to the reaction with other components
to form nonvolatile products. Another reason could be due
to evaporation. Dimethyl disulfide might escape through
packaging materials slowly during 21 d of refrigerated
storage. The content of pentane also was significantly reduced, which was statistically significant by Tukey group
analysis. At 0 d of storage, its content was higher than
10,000 × 104 ion counts for samples of all three irradiation
conditions. But after storage, all were reduced to near 2,000
× 104 ion counts. The content of hexane, heptane, and
octane was also significantly reduced. Because those alkanes are chemically inert, the reduction of those compounds in volatiles after storage should be due to evaporation, or dissolved into fats inside meat. The content of 3methyl butanal and 2-methyl butanal were also reduced
after storage. After 21 d of storage, a low amount of hexanal
was detected in volatiles. Low hexanal content in volatiles
was in agreement with the low TBARS values of breast
fillets (Table 1), as hexanal content in volatiles was suggested to be a good indicator of lipid oxidation (Shahidi
and Pegg, 1994; Ahn et al., 1998). Besides hexanal, the
contents of other aldehydes decreased after 21 d of storage.
This decrease might be due mainly to chemical reactions,
as aldehydes are highly reactive. The content of propanone
in volatiles, however, increased more than tenfold during
storage. The reason is not clear. The total volatile content
after 21 d of storage was reduced, especially for irradiated
samples (Tables 4 and 5).
In conclusion, results showed that TBARS values for
chicken breast fillets from all treatments were very low.
Thus, irradiating raw meat under aerobic packaging followed by 3 d of aerobic packaging did not induce significant oxidation in meat. Irradiating raw breast fillets increased the redness color of fillets after cooking, and 3-d
display of raw fillets in aerobic conditions after irradiation
could remove the color change on the surface of cooked
fillets that were induced by irradiation. Irradiation induced
production of alkanes, aldehydes, and dimethyl disulfide.
Those volatiles might be the breakdown products of fatty
acids and amino acids. The total volatile content lowered
after 21 d of storage. For raw meats that were irradiated
under aerobic conditions and then kept in aerobic conditions and storage at 4 C for 3 d before cooking, irradiation
effect on the volatiles of cooked meat seemed to disappear.
This result illustrated that aerobic display after irradiation
was effective for eliminating irradiation odor.
TABLE 4. The effect of irradiation conditions on the volatiles
of cooked chicken breast meat at 0 d of storage1
0 kGy
Volatiles
1
V-C-I
2
V-I-C
3 kGy
3
A-I-C
SEM
(total ion counts × 10 )
809a
1,119a
1,435b
3,738a
5,930b
5,837b
0b
37b
0b
67b
424a
474a
269a
36b
21c
228b
590a
604a
0b
0b
0b
2b
0b
2b
156b
195b
134a
26b
24c
80b
563b
603b
0b
11b
46ab
0b
219a
14b
229a
66b
7b
18b
0b
3b
466a
16b
1,979ab
920b
38ab
0b
395a
4b
77ab
0b
13,811b
14,100b
V-C-I
4
1-Butene
Acetaldehyde
Pentane
2,5-Dihydrofuran
Propanal
Propanone
2-Propanol
2-Methyl propanal
Hexane
Butanal
Methyl cyclopentane
2-Methyl 1-propanol
3-Methyl butanal
Tetramethyl butane
2-Methyl butanol
Heptane
Pentanal
2,4-Dimethyl hexane
2,3,4-Trimethyl pentane
2,3,3-Trimethyl pentane
Dimethyl disulfide
Methyl benzene
1-Octene
Octane
2-Octene
3-Methyl 2-heptane
4-Octene
Total
1,026a
1,734b
11,885a
266a
462a
332a
106b
446a
828a
90a
33a
21a
399a
128a
219a
1,025a
111a
63a
181a
257a
87a
25a
523a
2,640a
123a
451a
136a
23,597a
V-I-C
A-I-C
SEM
(total ion counts × 10 )
1,331a
1,499a
3,646a
4,080a
a
13,602
11,698a
12b
208a
351a
68b
300a
322a
184a
0c
656b
643b
792a
859a
127a
84a
14a
4a
6b
5b
1,075b
1,118b
69a
0b
727b
638b
1,037a
1,093a
144a
442a
30a
9a
98a
0b
314a
6a
259b
11c
76b
16c
265a
25b
1,435a
1,174a
80a
22a
205a
4b
59a
0b
26,894a
24,028a
4
151
441
870
16
59
246
34
49
72
9
7
4
30
29
15
74
26
16
36
41
13
4
102
376
34
87
31
1,804
1,383a
5,271a
12,630a
301a
555a
281a
73b
1,075a
837a
148a
24a
70a
1,910a
51a
1,091a
1,201a
162a
44a
93a
129a
483a
204a
255a
1,537a
56a
193a
59a
30,116a
134
595
1,758
65
95
103
18
54
129
49
6
5
113
14
66
146
204
11
14
107
33
13
39
210
24
33
13
3,005
a-c
Means within a row of same irradiation dosage with different superscripts differ significantly (P < 0.05); n
= 4.
1
V-C-I = raw meat was cooked in vacuum packaging, and the cooked meat was then irradiated; V-I-C = raw
meat was irradiated and stored in vacuum packaging, and then cooked; A-I-C = raw meat was irradiated and
stored in aerobic packaging, and then cooked.
QUALITY OF BROILER BREAST FILLETS IRRADIATED BEFORE AND AFTER COOKING
1753
TABLE 5. The effect of irradiation conditions on the volatiles
of cooked chicken breast meat after 21 d of storage1
0 kGy
Volatiles
1
V-C-I
2
V-I-C
3 kGy
3
A-I-C
SEM
V-C-I
(total ion counts × 10 )
1-Butene
Acetaldehyde
Pentane
2,5-Dihydrofuran
Propanal
Propanone
2-Propanol
2-Methyl propanal
2-Methyl propenal
Hexane
Butanal
Methyl-cyclopentane
2-Butanone
2-Methyl 1-propanol
3-Methyl butanal
2,2,3-Trimethyl butane
2-Methyl butanal
Heptane
Pentanal
2,4-Dimethyl hexane
2,3,4-Trimethyl pentane
2,3,3-Trimethyl pentane
Dimethyl disulfide
1-Octene
Octane
2-Octene
Hexanal
Total
186a
6,620a
2,596a
434a
504a
4,107a
39a
259a
31a
134ab
124a
1,412a
290a
8a
950a
0a
992a
341a
571a
0a
15a
20a
11a
12a
57a
3a
81a
19,797a
189a
6,680a
1,793b
280a
423a
5,864a
63a
252a
12b
166a
89a
23b
125b
2a
425ab
0a
323b
187ab
56b
0a
4b
9ab
4b
1a
2a
0a
1a
16,972ab
108b
3,356b
955c
5a
112a
5,225a
27a
44b
0b
79b
15b
2b
36b
0a
12b
0a
7b
33b
2b
0a
0b
4b
0b
0a
0a
0a
1a
10,023b
V-I-C
A-I-C
SEM
(total ion counts × 10 )
4
4
17
662
218
173
257
810
24
37
6
22
19
224
35
4
237
0
162
69
126
0
3
4
2
3
20
1
38
2,466
173a
6,511a
2,184a
530a
843a
6,283a
69a
258a
13a
217a
89a
268a
266a
18a
1,245a
6b
485a
210a
168a
0b
19b
39a
7b
34a
76a
26a
157a
20,194a
228a
4,384b
1,741a
11b
310a
7,005a
47a
268a
21a
236a
59ab
16b
137b
17a
516b
42ab
518a
197a
3a
38a
74a
99a
58a
9a
20a
4a
0a
16,058ab
156a
2,057c
1,762a
13b
230a
4,674a
8b
29b
0b
101a
34b
0b
48b
2a
37b
67a
29b
129b
4a
17ab
65a
87a
5b
11a
22a
2a
0a
9,589b
19
531
235
133
355
812
12
24
3
43
11
71
43
7
236
13
60
23
58
8
13
18
7
18
43
14
86
2,802
a-c
Means within a row of same irradiation dosage with different superscripts differ significantly (P < 0.05); n
= 4.
1
V-C-I = raw meat was cooked in vacuum packaging, and the cooked meat was then irradiated; V-I-C = raw
meat was irradiated and stored in vacuum packaging, and then cooked. A-I-C = raw meat was irradiated and
stored in aerobic packaging, and then cooked.
ACKNOWLEDGMENT
The project was supported by the Hatch Act and S-292.
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