Meat Science 63 (2003) 389–395
www.elsevier.com/locate/meatsci
Combination of aerobic and vacuum packaging to control lipid
oxidation and off-odor volatiles of irradiated raw turkey breast
K.C. Nam, D.U. Ahn*
Department of Animal Science, Iowa State University, Ames, IA 50011-3150, USA
Received 11 February 2002; received in revised form 23 April 2002; accepted 23 April 2002
Abstract
Effects of the combination of aerobic and anaerobic packaging on color, lipid oxidation, and volatile production were determined
to establish a modified packaging method to control quality changes in irradiated raw turkey meat. Lipid oxidation was the major
problem with aerobically packaged irradiated turkey breast, while retaining characteristic irradiation off-odor volatiles such as
dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide was the concern for vacuum-packaged breast during the 10-day refrigerated storage. Vacuum packaging of aerobically packaged irradiated turkey breast meat at 1 or 3 days of storage lowered the
amounts of S-volatiles and lipid oxidation products compared with vacuum- and aerobically packaged meats, respectively. Irradiation increased the a-value of raw turkey breast, but exposing the irradiated meat to aerobic conditions alleviated the intensity of
redness. # 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Combination of aerobic/anaerobic packaging; Irradiation; Lipid oxidation; Off-odor; Color
1. Introduction
One of the best emerging technologies to ensure the
microbiological safety of meat is irradiation. Up to 3
kGy of irradiation is allowed for use in poultry meat
(USDA, 1999). The main concern of irradiating meat,
however, is the organoleptic quality changes that occur
(Ahn et al., 1997). Ionizing radiation produces free
radicals that can accelerate oxidative processes and
produce radiolytic products from meat components
(Woods & Pikaev, 1994).
Previous studies showed that irradiation increased
lipid oxidation in aerobically packaged meat and developed off-flavors (Ahn, Nam, Du, & Jo, 2001; Patterson
& Stevenson, 1995). Jo and Ahn (2000) reported that
the radiolytic degradation of amino acids, especially
sulfur amino acids, was the main mechanism of off-odor
production in irradiated meat. Therefore, both lipid
oxidation products and radiolytic S-volatiles contributed to the overall off-flavor in irradiated raw meat.
However, the characteristic irradiation off-odor was
* Corresponding author. Tel.: +1-515-24-6895; fax: +1-515-2949143.
E-mail address: duahn@iastate.edu (D.U. Ahn).
influenced much more by the sulfur-volatiles such as
dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide than by lipid oxidation-dependent volatiles such
as aldehydes (Ahn, Jo, Du, Olson, & Nam, 2000). The
profiles and amounts of volatiles in irradiated meats
showed that these S-volatiles were higher in vacuumpackaged than aerobically packaged meats because they
were highly volatile under aerobic conditions (Ahn, Jo,
Du et al., 2000, 2001). Therefore, aerobic packaging will
be more beneficial in reducing the characteristic irradiation off-odor during refrigerated storage than
vacuum packaging, unless lipid oxidation is a problem.
The color of irradiated meat also depended upon
packaging type. Turkey breast meat became pinker after
irradiation (Lynch, MacFie, & Mead, 1991; Nam &
Ahn, 2002), and the increased pink color was more
intense and stable under vacuum than aerobic conditions (Luchsinger et al., 1996; Nam & Ahn, 2002). Thus,
aerobic packaging was more desirable for the irradiated
meat color than vacuum packaging, if lipid oxidation
was not considered.
Packaging is a critical factor that affects the quality of
irradiated meat, and thus, modification of packaging
methods can minimize the quality defect in irradiated meat. Exposing meat to aerobic conditions during
0309-1740/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S0309-1740(02)00098-0
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K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 389–395
irradiation and for certain periods of time during storage will help off-odor volatiles to escape from the meat.
Therefore, an appropriate combination of aerobic- and
vacuum-packaging conditions can be effective in minimizing both off-odor volatiles and lipid oxidation in
irradiated raw turkey breast during storage. It may also
be effective in reducing the generation of pink color in
irradiated meat compared with vacuum packaging
alone.
The objectives of this study were to determine the
effects of modified packaging conditions on lipid oxidation, volatiles, and color of irradiated raw turkey breast
meat during refrigerated storage, and to find the best
aerobic and vacuum packaging combination that can
minimize quality defect of irradiated meat.
2. Materials and methods
2.1. Sample preparation
Turkey breast muscles (Pectoralis major+minor) were
separated from a total of 32 turkeys and sliced into 2-cm
thick steaks. For modification of packaging conditions
during the storage, the sliced samples were individually
packaged in oxygen-permeable bags (polyethylene,
Associated Bag Company, Milwaukee, WI) and irradiated at 3 kGy using a Linear Accelerator (Circe IIIR,
Thomson CSF Linac, Saint-Aubin, France) at room
temperature; 10 MeV of energy, 10 kW of power level,
and 92.6 kGy/min of average dose rate were used. To
confirm the target dose, alanine dosimeters attached to
the top and bottom of sample were read using an 104
Electron Paramagnetic Resonance unit (EMS-104, Bruker Instruments Inc., Billerica, MA). The max./min.
ratio was approximately 1.3. Then, a few of them were
doubly vacuum-packaged in a larger vacuum bag
(nylon/polyethylene, 9.3 ml O2/m2/24 h at 0 C; Koch,
Kansas City, MO) after 1, 3, or 5 days of refrigerated
storage until 10 days of storage for A1/V9 (aerobic for 1
day then vacuum for 9), A3/V7 (aerobic for 3 days
then vacuum for 7), or A5/V5 (aerobic for 5 days then
vacuum for 5) treatment, respectively. Nonirradiated
aerobically packaged samples were used as a control.
Irradiated aerobically and vacuum-packaged samples
were prepared for references. Color, lipid oxidation, and
volatile compounds of the samples were determined at 0
and 10 days of storage. The data of A1/V9, A3/V7, and
A5/V5 at 0 days were represented by those of irradiated
aerobically packaged samples.
2.2. Color measurement
CIE color values were measured (AMSA, 1991) on
the surface of samples using a LabScan color meter
(Hunter Associated Labs, Inc., Reston, VA) that had
been calibrated against black and white reference tiles
covered with the same packaging materials as used for
samples. The CIE L (lightness), a (redness), and b (yellowness) values were obtained using an illuminant A
(light source). An average value from both top and
bottom location on a sample surface was used for statistical analysis.
2.3. Analysis of 2-thiobarbituric acid reactive substances
(TBARS)
Lipid oxidation was determined by a TBARS method
(Ahn, Olson, Jo, Chen, Wu & Lee, 1998). Minced sample (5 g) was placed in a 50-ml test tube and homogenized with 15 ml of deionized distilled water (DDW)
using a Brinkman Polytron (Type PT 10/35, Brinkman
Instrument Inc., Westbury, NY) for 15 s at high speed.
The meat homogenate (1 ml) was transferred to a disposable test tube (13100 mm), and butylated hydroxytoluene (7.2%, 50 ml) and thiobarbituric acid/
trichloroacetic acid [20 mM TBA and 15% (w/v) TCA]
solution (2 ml) were added. The mixture was vortexed
and then incubated in a 90 C water bath for 15 min to
develop color. After cooling for 10 min in cold water,
the samples were vortexed and centrifuged at 3000g
for 15 min at 5 C. The absorbance of the resulting
upper layer was read at 531 nm against a blank prepared with 1 ml DDW and 2 ml TBA/TCA solution.
The amounts of TBARS were expressed as mg per kg of
meat.
2.4. Analysis of volatile compounds
A purge-and-trap apparatus (Precept II and Purge &
Trap Concentrator 3000, Tekmar-Dohrmann, Cincinnati, OH) connected to a gas chromatograph/mass
spectrometer (GC Model 6890/MSD, HP 5973, Hewlett-Packard Co., Wilmington, DE) was used to analyze
the volatiles potentially responsible for the off-odor in
samples (Ahn et al., 2001). Minced sample (3 g) was
placed in a 40-ml sample vial, and the vials were then
flushed with helium gas (40 psi) for 5 s. The maximum
holding time of a sample in a refrigerated (4 C) loading
tray was less than 4 h to minimize oxidative changes
during the waiting period before starting analysis. The
sample was purged with helium gas (40 ml/min) for 12
min at 40 C. Volatiles were trapped at 20 C using a
Tenax/charcoal/silica trap column (Tekmar-Dohrmann),
thermally desorbed (225 C) into a cryofocusing unit
( 90 C), and then thermally desorbed at 225 C into a
GC column for 30 s. An HP-624 column (7.5 m, 250 mm
i.d., 1.4 mm nominal), an HP-1 column (52 m, 250 mm
i.d., 0.25 mm nominal), and an HP-Wax column (7.5 m,
250 mm i.d., 0.25 mm nominal) combined with zero
dead-volume column connectors (Hewlett Packard Co.)
were used to improve the separation of volatiles. A
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K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 389–395
ramped oven temperature was used (0 C for 2.5 min,
increased to 15 C at 2.5 C/min, increased to 45 C at
5 C/min, increased to 110 C at 20 C/min, and
increased to 200 C at 10 C/min for 3.25 min). Liquid
nitrogen was used to cool the oven below ambient temperature. Helium was the carrier gas at a constant pressure of 20.5 psi. The ionization potential of MS was 70
eV, and the scanned mass range was 18.1–300 m/z.
Identification of volatiles was achieved by comparing
mass spectral data of samples with those of the Wiley
library (Hewlett-Packard Co.). Selected standards were
used to verify the identities of some volatiles. Each peak
area was integrated using the ChemStationTM software
(Hewlett Packard Co.) and reported as the amount of
volatiles released (total ion counts104).
2.5. Statistical analysis
The experiments were performed by four replications
and designed to determine the effects of modified
packaging methods and storage time on color, lipid
oxidation, and volatile compounds of the irradiated
samples during the 10 days of storage. Analysis of variance was used by the generalized linear model procedure
of SAS software (SAS Institute, 1995); StudentNewman–Keul’s multiple range test was used to compare the mean values of the treatments. Mean values
and standard error of the means (SEM) were reported
(P < 0.05).
3. Results and discussion
3.1. Color changes
Irradiation made turkey breast meat redder, and the
increased redness was more distinct in irradiated
vacuum-packaged than aerobically packaged meats
(Table 1). Nam and Ahn (2002) attributed the increased
red color in irradiated turkey meat to the formation of
carbon monoxide–myoglobin (CO–Mb) complex.
Compared with oxymyoglobin, CO–Mb complex is not
easily oxidized to brown metmyoglobin, because of the
strong binding of CO to the iron-porphyrin in myoglobin molecule (Sorheim, Nessen, & Nesbakken, 1999).
The redness of irradiated aerobically packaged turkey
breast was lower than vacuum-packaged breast, but it
was still higher than that of the nonirradiated control.
After 10 days of storage, the redness of aerobically or
doubly packaged turkey breast was not changed,
whereas that of vacuum-packaged breast significantly
increased. Therefore, exposing irradiated meat to aerobic conditions was effective in reducing pink color in
irradiated turkey breast meat. Although the binding
affinity of CO–myoglobin is 200-fold stronger than O2
(Stryer, 1981), the continuous challenge from oxygen
Table 1
Color values of irradiated raw turkey breast meat with different
packaging during refrigerated storageab
Storage NonIr
Irradiated
SEM
c
Aerobic Aerobic A5/V5
L-value
Day 0 47.7a
Day 10 50.1
SEM
0.8
d
A3/V7
e
A1/V9
Vacuum
45.8aby 45.8aby 45.8aby 45.8aby 43.6by
48.9x
51.8x
51.6x
51.0x
48.8x
0.5
0.7
0.6
0.7
0.5
0.5
0.9
a-value
Day 0
Day 10
SEM
2.5cx
1.8cy
0.2
3.5b
3.3b
0.2
3.5b
3.1b
0.2
3.5b
4.0b
0.2
3.5b
4.0b
0.3
4.9ay
5.6ax
0.2
0.2
0.3
b-value
Day 0
Day 10
SEM
4.3
5.3
0.3
4.4
4.8
0.3
4.4y
6.5x
0.4
4.4y
6.4x
0.3
4.4
5.1
0.3
3.6
5.0
0.6
0.3
0.4
a
Different letters (a–c) within a row are significantly different
(P<0.05). n=4.
b
Different letters (x,y) within a column with same color value are
significantly different (P <0.05).
c
Aerobically packaged for 5 days and then vacuum packaged for 5
days.
d
Aerobically packaged for 3 days and then vacuum packaged for 7
days.
e
Aerobically packaged for 1 day and then vacuum packaged for 9
days.
under aerobic conditions should have replaced CO–Mb
ligand to MbO2, which oxidized easily to metMb and
decreased pink color intensity. Grant and Patterson
(1991) also reported that irradiated meat color could be
discolored at the presence of oxygen. There was no difference in color a-values among doubly packaged samples with different exposure time to aerobic conditions,
and even aerobic exposure for 1 day after irradiation
was effective in reducing the redness. However, none of
the aerobic/vacuum packaging combinations (‘‘double
packaging’’) could lower color a-values of irradiated
turkey meat to the level of the nonirradiated control.
3.2. Lipid oxidation
Vacuum-packaged meat was more resistant to lipid
oxidation than aerobically packaged meat irrespective
of irradiation dose at 0 days, but irradiation accelerated
lipid oxidation during the 10-days storage (Table 2). At
day 10, the TBARS of irradiated turkey breast meat was
commensurate with the exposing time to aerobic conditions. This showed that the increased lipid oxidation
was mainly problematic only when irradiated turkey
breast meat was aerobically stored, and the presence of
oxygen was the most critical factor influencing lipid
oxidation during the storage of irradiated meat.
Although the TBARS of doubly packaged meats were
still higher than those of the vacuum-packaged meats,
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K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 389–395
Table 2
TBARS values of irradiated raw turkey breast meat with different packaging during refrigerated storageab
Storage
Day 0
Day 10
SEM
a
b
c
d
e
NonIr
Irradiated
SEM
Aerobic
Aerobic
A5/V5c
0.53ay
1.99bx
0.17
0.65ay
2.63ax
0.14
(mg / kg meat)
0.65ay
0.65ay
1.97bx
1.33cx
0.18
0.07
A3/V7d
A1/V9e
Vacuum
0.65ay
0.92cdx
0.04
0.34b
0.43d
0.03
0.03
0.16
Different letters (a–d) within a row are significantly different (P <0.05). n=4.
Different letters (x,y) within a column are significantly different (P<0.05).
Aerobically packaged for 5 days and then vacuum packaged for 5 days.
Aerobically packaged for 3 days and then vacuum packaged for 7 days.
Aerobically packaged for 1 day and then vacuum packaged for 9 days.
they were significantly lower than those of the aerobically packaged meats with or without irradiation.
Therefore, 1–3 days of aerobic packaging of irradiated
raw turkey breast meat during the 10 days did not cause
any problem in lipid oxidation.
Table 3
Volatile profile of irradiated raw turkey breast meat with different
packaging at day 0a
Compound
NonIr
Irradiated
Aerobic
Aerobic
3.3. Off-odor volatiles
Table 3 shows that irradiation produced many new
volatiles and increased the amounts of a few volatiles
found in nonirradiated turkey breast meat. Specific
volatiles generated by irradiation include methanethiol,
methylthio ethane, dimethyl disulfide, dimethyl trisulfide, propanal, 3-methyl butanal, pentanal, and toluene. The amount of total volatiles in turkey breast with
vacuum packaging was only about half that of the
aerobically packaged meat, indicating that considerable
amounts of volatiles were evaporated during the storage
period under aerobic conditions. The predominant
volatile of nonirradiated control meat was dimethyl
sulfide, but the amount was not changed much by irradiation. The composition of S-volatiles in irradiated
turkey meat differs greatly depending on the packaging
methods used. For example, the ratio of dimethyl sulfide to dimethyl disulfide was 10:1 in aerobically packaged turkey breast, while the ratio was changed to 1:1 in
vacuum-packaged irradiated turkey breast. All of these
S-compounds are regarded as major volatiles responsible for the characteristic irradiation off-odor, which is
different from the rancidity produced by lipid oxidation
products. Ahn, Jo, and Olson (2000) described the irradiation odor in raw pork as a ‘‘barbecued corn-like’’
odor. S-containing volatiles, such as 2,3-dimethyl disulfide produced by the radiolytic degradation of sulfur
amino acids, were responsible for the off-odor in irradiated pork, and their amounts were highly dependent
upon irradiation dose (Ahn, Jo, Du et al., 2000). Jo and
Ahn (2000) also found that 2,3-dimethyl disulfide was
produced from irradiated oil emulsion containing
methionine. This different composition of S-volatiles as
well as their absolute amount may have significant effect
2-Methyl-1-propene
Methanethiol
1-Pentene
Pentane
2-Pentene
Propanal
Dimethyl sulfide
1-Hexene
Hexane
Methylthio ethane
Benzene
3-Methyl butanal
1-Heptene
Heptane
Pentanal
Dimethyl disulfide
Toluene
1-Octene
Octane
2-Octene
3-Methyl-2-heptene
Dimethyl trisulfide
Total
0b
0b
0c
310b
0b
0b
4601
0b
183c
0b
0b
0b
0c
51c
0b
0c
0b
0b
289c
0c
0b
0b
5436c
SEM
Vacuum
(Total ion counts104)
133a
153a
226b
1280a
125a
74b
717a
455b
43a
0b
80a
0b
4534
6898
69a
55a
472a
284b
75a
67a
195a
222a
71a
62a
205a
124b
264a
122b
58a
63a
430b
4266a
1254a
1339a
66b
259a
658b
837a
69b
178a
0b
233a
84b
814a
9857b
17,772a
8
79
11
64
1
5
599
4
15
3
11
4
10
11
6
295
68
26
48
3
11
39
694
a
Different letters (a–c) within a row are significantly different
(P<0.05). n=4.
on the descriptive characteristics of the irradiation offodor because each S-volatile has its own characteristic odor note and threshold. Dimethyl disulfide produced
more stringent and stronger odor than dimethyl sulfide.
Therefore, the odor of vacuum-packaged meat would be
more stimulating than that of aerobically packaged
meat because of high dimethyl disulfide in the meat.
After 10 days of refrigerated storage, volatile profiles
of irradiated turkey breast were highly dependent upon
packaging conditions (Table 4). The greatest amounts
of total volatiles and S-volatiles were detected in
393
K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 389–395
The major aldehydes produced in aerobically packaged irradiated turkey breast at 10 days were propanal,
pentanal, and hexanal, and considerable amounts of
these aldehydes were found in A5/V5 (aerobic conditions for 5 days then vacuum conditions for 5 days)
doubly packaged irradiated samples (Table 5). Ketones
such as 2-propanone and 4-pentanone were produced
mainly in aerobically packaged turkey breast meat
regardless of irradiation dose, and 2-propanone was the
most representative volatile compound in nonirradiated
aerobically packaged turkey meat after 10 days of storage (Table 5).
S-volatiles in vacuum-packaged irradiated turkey
breast meat at day 10 consisted of dimethyl sulfide
vacuum-packaged irradiated turkey breast meat. Significantly,the amount of S-volatiles was inversely related
to the exposure time to aerobic conditions. On the other
hand, the total amount of aldehydes in irradiated turkey
breast increased with the time in aerobic conditions and
agrees with TBARS (Table 2). The amount of total Svolatiles in irradiated turkey breast meat with A3/V7
(aerobic conditions for 3 days and then vacuum packaging for 7 days) double packaging was only about 10%
that of vacuum packaged, and the amount of total
aldehydes was 22% of aerobically packaged meat. The
amount of total ketone, however, was proportional to
the time with aerobic conditions irrespective of irradiation dose.
Table 4
Volatile profile of irradiated raw turkey breast meat with different packaging at day 10a
Compound
Aldehydes
Ketones
S-compounds
Hydrocarbons
Others
Total
a
b
c
d
NonIr
Irradiated
SEM
Aerobic
Aerobic
A5/V5b
A3/V7c
A1/V9d
Vacuum
72e
12396a
1136e
2596c
98a
16,302b
1503a
11,338a
1167e
4761ab
47a
18,825b
(Total ion counts104)
1103b
340c
9863ab
9273ab
1870d
2607c
6189ab
7341a
52a
0b
19,087b
16,743b
177d
8930b
5462b
3462b
0b
18,037b
165d
5867c
25,311a
4983b
0b
36,336a
20
243
87
37
6
97
Different letters (a–e) within a row are significantly different (P <0.05). n=4.
Aerobically packaged for 5 days and then vacuum packaged for 5 days.
Aerobically packaged for 3 days and then vacuum packaged for 7 days.
Aerobically packaged for 1 day and then vacuum packaged for 9 days.
Table 5
The content of aldehydes, ketones, and other volatiles in irradiated raw turkey breast meat with different packaging at day 10a
Compound
NonIr
Aerobic
Irradiated
Aerobic
SEM
b
A5/V5
c
A3/V7
d
A1/V9
Vacuum
(Total ion counts104)
Aldehydes
Propanal
Butanal
3-Methyl butanal
Pentanal
Hexanal
72b
0c
0b
0c
0b
983a
73a
37a
157a
253a
865a
51b
0b
139a
48b
269b
0c
0b
71b
0b
125b
0c
0b
52b
0b
106b
0c
0b
59b
0b
57
2
1
16
23
Ketones
2-Propanone
2-Butanone
3-Pentanone
12,117a
128b
151a
11,141ab
197a
0b
9696ab
167ab
0b
9138b
135b
0b
8772b
158ab
0b
5802c
65c
0b
716
12
8
Others
Acetate, ethyl ester
2-Ethyl furan
Total
47a
51a
12,566a
0b
47a
12,888a
0b
52a
11,018b
0b
0b
9613c
0b
0b
9107c
0b
0b
6032d
3
5
84
a
b
c
d
Different letters (a–c) within a row are significantly different (P <0.05). n=4.
Aerobically packaged for 5 days and then vacuum packaged for 5 days.
Aerobically packaged for 3 days and then vacuum packaged for 7 days.
Aerobically packaged for 1 day and then vacuum packaged for 9 days.
394
K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 389–395
Table 6
Sulfur-containing volatiles of irradiated raw turkey breast meat with different packaging at day 10a
Compound
Methanethiol
Dimethyl sulfide
Carbon disulfide
Methylthio ethane
Dimethyl disulfide
Dimethyl trisulfide
Total
a
b
c
d
NonIr
Irradiated
Aerobic
Aerobic
(Total ion counts104)
0b
0b
1033d
1024d
103a
103a
0b
0b
0b
40b
0b
0b
1136e
1167e
SEM
A5/V5b
A3/V7c
A1/V9d
Vacuum
0b
1774cd
62b
0b
34b
0b
1870d
0b
2576c
0c
0b
31b
0b
2607c
0b
5346b
0c
0b
116b
0b
5462b
1505a
15,101a
0c
47a
8020a
638a
25,311a
91
316
4
1
91
22
87
Different letters (a–e) within a row are significantly different (P <0.05). n=4.
Aerobically packaged for 5 days and then vacuum packaged for 5 days.
Aerobically packaged for 3 days and then vacuum packaged for 7 days.
Aerobically packaged for 1 day and then vacuum packaged for 9 days.
Table 7
Hydrocarbons of irradiated raw turkey breast meat with different packaging at day 10a
Compound
NonIr
Irradiated
Aerobic
Aerobic
SEM
A5/V5b
A3/V7c
A1/V9d
Vacuum
199b
0c
66bc
835bc
55c
0b
54b
372
131b
90b
139c
563b
168bc
484b
144bc
162b
3462b
528a
0c
130ab
467c
133b
0b
110a
408
222a
71b
75d
713a
434a
898a
265a
529a
4983b
4
2-Methyl-1-propene
Butane
1-Pentene
Pentane
2-Pentene
3-Methyl pentane
1-Hexene
Hexane
Benzene
1-Heptene
Heptane
Toluene
1-Octene
Octane
2-Octene
3-Methyl-2-heptene
Total
a
b
c
d
0e
71b
49c
1633ab
0d
0b
0c
447
49c
0c
130c
40d
0d
101e
76c
0c
2596c
77d
209a
111bc
2202a
115b
51a
71b
639
61bc
158a
261ab
370c
44d
202d
101bc
89b
4761ab
(Total ion counts10 )
90d
150c
212a
192a
180a
107bc
2518a
1615ab
204a
116b
0b
0b
76b
53b
719
595
118b
126b
154a
107b
351a
234bc
355c
430c
214b
145c
557b
368c
285a
166b
156b
109b
6189ab
7341a
16
18
17
257
12
3
7
101
17
11
30
25
16
31
19
19
37
Different letters (a–e) within a row are significantly different (P <0.05). n=4.
Aerobically packaged for 5 days and then vacuum packaged for 5 days.
Aerobically packaged for 3 days and then vacuum packaged for 7 days.
Aerobically packaged for 1 day and then vacuum packaged for 9 days.
and dimethyl disulfide as at day 0 (Table 6). The
main difference between 0 and 10 day stored vacuumpackaged irradiated meats was the amount of dimethyl
disulfide and dimethyl sulfide, which increased two-fold
over the storage time. Dimethyl trisulfide, methanethiol,
and methanethiol ethane were found in only vacuumpackaged irradiated turkey breast. Under aerobic conditions, on the other hand, almost all S-compounds,
except for dimethyl sulfide, evaporated during the 10day storage period and clearly suggested that aerobic
packaging was more beneficial than vacuum packaging
in reducing S-volatiles responsible for the irradiation
off-odor. Aerobic packaging, however, promoted lipid
oxidation in turkey breast meat as evidenced by the
increased aldehydes and TBARS (Tables 2 and 5).
When both lipid oxidation and S-volatiles responsible
for irradiation off-odor should be considered, therefore,
doubly packaging turkey breast meat was far more
beneficial than the aerobic or vacuum packaging alone.
Turkey breast meat with A3/V7 double packaging
(aerobic conditions for 3 days then vacuum conditions
for 7 days) had only 17% dimethyl sulfide and 0.4%
dimethyl disulfide of vacuum-packaged irradiated
turkey breast, and other S-volatiles (methanethiol,
methylthiol ethane, and dimethyl trisulfide) were not
detected. In aerobically packaged nonirradiated turkey
K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 389–395
breast meat, dimethyl sulfide and carbon disulfide were
the predominant S-volatiles at day 10. The doublepackaging effect on the production of many of the
hydrocarbons in turkey breast at day 10 was inconsistent. The amounts of butane, pentane, 3-methylpentane, 1-heptene and heptane, however, showed
decreasing trends, and 2-methyl-1-propene, toluene, 1octene, and 3-methyl-2-heptene had increasing trends as
the exposure time to oxygen decreased (Table 7). The
amounts of benzene, toluene, 1-octene, octane, and 3methyl-2-heptene were higher in irradiated than nonirradiated meats. Thus, these hydrocarbons may also
have a certain effect on the irradiation off-odor. The
specific evaluation of each volatile compound to the
irradiation off-odor is beyond the scope of this work.
4. Conclusion
Irradiating and storing turkey breast meat for 1–3
days under aerobic conditions and then storing under
vacuum conditions (A1/V9 or A3/V7 double packaging)
could minimize irradiation off-odor by volatilizing Svolatile compounds. Vacuum packaging was required to
minimize lipid oxidation during the remaining storage
period. This double packaging can be an efficient way to
minimize the quality changes in poultry breast meat
caused by irradiation without adding any additives.
However, this modified packaging method involves with
some extra costs, labor, and time, and more efficient and
convenient modification of this concept will be needed.
Acknowledgements
Journal Paper No. J-19736 of the Iowa Agriculture and
Home Economics Experiment Station, Ames, IA 50011.
Project No. 3706, supported by State of Iowa funds.
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