Meat Science 63 (2003) 1–8
www.elsevier.com/locate/meatsci
Use of antioxidants to reduce lipid oxidation and off-odor
volatiles of irradiated pork homogenates and patties§
K.C. Nam, D.U. Ahn*
Department of Animal Science, Iowa State University, 1221 Kildee, Ames, IA 50011-3150, USA
Received 30 October 2001; received in revised form 11 January 2002; accepted 11 January 2002
Abstract
Pork homogenates and patties treated with antioxidants (200 mM, final) were irradiated with an electron beam. Lipid oxidation
of the pork homogenates and patties were determined at day 0 and 5 and volatile compounds were analyzed soon after irradiation.
Ionizing radiation accelerated lipid oxidation and produced S-containing volatiles in pork homogenates and patties. Addition of an
antioxidant (sesamol, gallate, Trolox, or a-tocopherol) and their combinations decreased, but carnosine did not affect the production of off-odor volatiles and lipid oxidation of pork homogenates and patties by irradiation. Antioxidant combinations showed
distinct beneficial reduction in lipid oxidation of aerobically packaged irradiated pork patties. The effect of antioxidant combinations in reducing sulfur volatiles of irradiated pork patties was clearer under vacuum than aerobic conditions. # 2002 Elsevier
Science Ltd. All rights reserved.
Keywords: Antioxidants; Irradiation; Lipid oxidation; Off-odor volatiles; Pork
1. Introduction
Irradiated meats are susceptible to oxidative quality
deterioration such as lipid oxidation and off-odor production. The quality of irradiated meat correlates closely with the amounts of radiolytic products (Woods &
Pikaev, 1994). Free radicals possess strong chemical
reactivity and can react with unsaturated fatty acids or
amino acid side chains of protein (McMillin, 1996). As a
result, irradiation promotes lipid oxidation and generates characteristic off-odor volatiles in meats. The
production of aldehydes and 2-thiobarbituric acid-reactive substances (TBARS) were irradiation dose-dependent, and had strong correlations with off-odor in
irradiated pork (Ahn, Jo, Du, Olson, & Nam, 2000).
The gas chromatograms of raw irradiated pork suggested that not only lipid oxidation but also other
mechanisms, such as radiolytic degradation of proteins,
§
Journal Paper No. J-19415 of the Iowa Agriculture and Home
Economics Experiment Station, Ames, IA 50011.
* Corresponding author. Tel.: +1-515-294-6595; fax: +1-515-2949143.
E-mail address: duahn@iastate.edu (D.U. Ahn).
played an important role in the off-odor production in
irradiated meat (Ahn, Nam, Du, & Jo, 2001). Jo and
Ahn (2000) reported that S-containing volatiles generated
from S-containing amino acids were responsible for
most of the characteristic irradiation odor in meat.
Antioxidant additives are added to fresh and further
processed meats to prevent oxidative rancidity, retard
development of off-flavors, and improve color stability
(Xiong, Decker, Robe, & Moody, 1993). Certain antioxidants can interrupt free radical chain reactions by
scavenging free radicals (Chen & Ahn, 1998) and using
specific antioxidants can reduce lipid oxidation and offodor formation by irradiation. Radiolytic changes in
meat are accelerated in the presence of oxygen and the
activities and mechanisms of selected antioxidants can
vary depending upon the composition of food systems.
To be effective, antioxidants added in meat must compete with reactive meat components for free radicals
generated by irradiation, or inhibit the formation of free
radicals induced by prooxidative metals. Therefore, free
radical scavengers (gallate, sesamol, and tocopherol),
metal chelators (Trolox) and intrinsic antioxidant (carnosine), or their combinations can be used to reduce the
production of off-odor volatiles in electron beam-radiated pork.
0309-1740/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S0309-1740(02)00043-8
2
K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 1–8
The effect of antioxidants on controlling oxidative
reactions in meat has been well documented. However,
the information on added antioxidant effects on lipid
oxidation and off-odor volatiles in irradiated meats is
lacking. In addition selected antioxidants may differ in
reducing lipid oxidation and S-containing volatiles in
irradiated meats depending upon the type and combinations of antioxidants and packaging method used.
Therefore, the objective of this study was to determine
the effect of selected antioxidants and their combinations on lipid oxidation and production of off-odor
volatiles in irradiated pork homogenates and patties
with aerobic or vacuum packaging.
2. Materials and methods
2.1. Antioxidants
Gallic acid (3,4,5-trihydroxybenzoic acid), sesamol (3,4methylenedioxyphenol), and l-carnosine (b-alanyl-l-histidine) were purchased from Sigma Chemical Company (St.
Louis, MO), and a-tocopherol (vitamin E) and Trolox (6hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid)
were obtained from Aldrich Chemical Co. (Milwaukee,
WI). The antioxidants were selected on the basis of their
antioxidant functions and solubility to water and lipids.
St. Joseph, MI) to ensure uniform distribution of the
added antioxidants. Pork patties (100 g) were prepared
and half of the patties from each treatment were aerobically packaged by individually placing in polyethylene
oxygen-permeable bags (1015 cm, 2 MIL-Associated
Bag Company, Milwaukee, WI) and the other half were
vacuum-packaged in high oxygen-barrier bags (nylon/
polyethylene, 9.3 ml O2/m2/24 h at 0 C; Koch, Kansas
City, MO). Four replications were performed for both
pork homogenate and patty studies.
2.3. Ionizing radiation and storage
Antioxidant-treated pork homogenates and patties
were electron beam-irradiated at 0 or 4.5 kGy using a
linear accelerator (Circe IIIR; Thomson CSF Linac,
Saint-Aubin, France) with 10 MeV of energy, 10 kW of
power level, and 104.5 kGy/min of average dose rate.
The max/min ratio was approximately 1.16 for 4.5 kGy.
Alanine dosimeters were attached to the top and bottom
surfaces of a sample, and read using a 104 Electron
Paramagnetic Resonance Instrument (Bruker Instruments Inc., Billerica, MA) to check the absorbed dose.
The irradiated samples were stored at 4 C. The TBARS
of the samples were determined at day 0 and 5, and
volatiles were analyzed soon after irradiation.
2.4. 2-Thiobarbituric acid-reactive substances (TBARS)
2.2. Preparation of pork homogenates and patties
Pork loins were purchased from four local stores.
Loins from each store were combined and separately
ground twice through a 3-mm plate and used as a replication. The ground meat (50 g) was homogenized with
deionized water (200 ml) using a laboratory blender
(Waring Commercial, New Hartford, CT) for 1 min at
high speed. Each antioxidant (gallic acid, tocopherol,
Trolox, sesamol or carnosine) was added in meat
homogenate to make a final concentration of 200 mM.
To determine the synergistic effects of selected antioxidants, several antioxidant combinations were prepared. Either 100 or 66.7 mM of each antioxidant was
added depending upon 2 or 3 antioxidant combinations
to make equal final total concentration of antioxidants
of 200 mM in all treatments. Three of the most effective
antioxidants or antioxidant combinations in reducing
off-odor production and TBARS in meat homogenates
were selected for the study with pork patties. The effects
of selected antioxidant on lipid oxidation and off-odor
volatiles of pork patties were determined.
To prepare antioxidant-treated pork patties, the three
different antioxidant combinations that produced the
least amount of off-odor volatiles from the previous
pork homogenate study were used. Ground pork and
antioxidants combination (final 200mM) were mixed for
3 min in a bowl mixer (Model KSM90; KitchenAid Inc.,
Lipid oxidation was determined by the TBARS
method (Ahn, Olson, Jo, Chen, Wu, & Lee, 1998). 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. A
meat homogenate (1 ml) was transferred to a disposable
test tube (13100 mm), and butylated hydroxytoluene
(7.2% in ethanol, v/v, 50 mL) and thiobarbituric acid/
trichloroacetic acid (20 mM TBA/15% TCA, w/v, 2 ml)
solutions 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 sample was 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 of malonedialdehyde
(MDA) per kg meat or per 4 l meat homogenate
(equivalent to 1 kg of meat).
2.5. Volatile compounds analysis
A purge-and-trap apparatus (Precept II and Purge &
Trap Concentrator 3000; Tekmar-Dohrmann, Cincinnati, OH) connected to a gas chromatograph/mass spectrometer (GC/MS; Hewlett-Packard Co., Wilmington,
K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 1–8
DE) was used to analyze volatiles produced (Ahn et al.,
2001). Minced meat sample (3 g) or meat homogenate (3
ml) was placed in a 40-ml sample vial, and the vials were
flushed with helium (40 psi) for 5 s. The maximum
waiting time of a sample in a refrigerated (4 C) holding
tray was less than 4 h to minimize oxidative changes
before analysis. The meat sample was purged with
helium (40 ml/min) for 12 min at 40 C. Volatiles were
trapped using a Tenax column (Tekmar-Dohrmann)
and desorbed for 2 min at 225 C, focused in a cryofocusing module ( 90 C) and then thermally desorbed
into a column for 30 s at 225 C. An HP-624 column (7.5
m 0.25 mm i.d., 1.4 mm nominal), an HP-1 column
(52.5 m0.25 mm i.d., 0.25 mm nominal; Hewlett-Packard Co.) and an HP-Wax column (7.5 m0.25 mm i.d.,
0.25 mm nominal) were connected using zero deadvolume column connectors (J&W Scientific, Folsom,
CA). Ramped oven temperature was used to improve
volatile separation. The initial oven temperature of 0 C
was held for 2.50 min. After that, the oven temperature
was 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, increased
to 210 C at 10 C/min, and then was held for 2.5 min at
210 C. Constant column pressure at 20.5 psi was
maintained. The ionization potential of the mass-selective detector (Model 5973; Hewlett-Packard Co.) was 70
eV, and the scan range was 18.1–250 m/z. Identification
of volatiles was achieved by comparing mass spectral
data of samples with those of the Wiley Library (Hewlett-Packard Co.). Standards, when available, were used
to confirm the identification by the mass-selective
detector. The area of each peak was integrated using the
ChemStationTM (Hewlett-Packard Co.), and the peak
area (total ion counts104) was reported as an indicator
of volatiles generated from the sample.
2.6. Statistical analysis
This experiment was designed to determine the antioxidant effects on lipid oxidation and volatile profiles of
the nonirradiated and irradiated samples. Analysis of
variance was conducted using the generalized linear model
procedure of the SAS software (SAS Institute, 1995);
Student–Newman–Keul’s multiple range tests were used
to compare the mean values. Mean values and standard
error of the means (SEM) were reported (P < 0.05).
3. Results and discussion
3.1. Lipid oxidation
Irradiation and antioxidants affected the TBARS
values of pork homogenates during storage (Table 1).
Irradiated pork homogenates had higher TBARS than
nonirradiated in all antioxidant treatments. The added
3
antioxidant effect to reduce TBARS was found in irradiated pork homogenates, but not in nonirradiated.
Most antioxidants but carnosine at 200 mM levels
decreased the TBARS of irradiated pork homogenates.
The antioxidant effects in meat homogenates were more
notable after 5 days of storage. Sesamol and Trolox were
superior to other antioxidants and reduced TBARS of
irradiated pork homogenate by 72% of control at day 5.
The effects of antioxidants in nonirradiated pork homogenates could not be found even at day 5.
TBARS values of pork homogenates treated with
antioxidant combinations (Table 2) also showed similar
trends as in individual antioxidant treatments (Table 1).
However, it is impossible to compare the TBARS values
from the two studies (Tables 1 and 2) directly because
we used meat samples having different storage history at
different times. Although the effects of antioxidant
combinations were significant in irradiated pork homogenates, the difference among antioxidant combinations
was minimal at day 0. The effects of antioxidant combinations, however, were distinct after 5 days of storage.
The sesamol plus tocopherol, or Trolox plus tocopherol
was more effective than other combinations in inhibiting
lipid oxidation. These 2-antioxidant combinations
reduced TBARS of irradiated pork homogenates by
47% of the control at 5 days storage. The combination
of sesamol plus g-tocopherol was efficient in inhibiting
hydroperoxide formation in oils (Yoshida & Takagi,
1999). The effects of 3-antioxidant combinations were
not different from those of 2-antioxidant combinations.
Irradiation, antioxidants, and packaging methods
influenced the TBARS values of pork patties during
storage (Table 3). Pork patties were susceptible to lipid
oxidation, especially when irradiated and stored in the
presence of oxygen. Antioxidant combinations decreased
TBARS in both nonirradiated and irradiated pork patties under aerobic conditions, but there were little differences among antioxidant combinations at day 0.
Vacuum-packaged patties did not develop lipid oxidation at day 0 regardless of irradiation and antioxidant
treatments, but the effects of irradiation and antioxidant
combination were evident at day 5. When irradiated and
stored for 5 days, the effects of antioxidant combinations on oxidative changes in pork patties were more
distinct in aerobically packaged than vacuum-packaged
pork, but the differences among antioxidant combinations were still minimal. Chen, Jo, Lee, and Ahn (1999)
also reported that phenolic antioxidants were effective
in reducing lipid oxidation in aerobically packaged
irradiated pork patties. All treated antioxidant combinations reduced TBARS of aerobically and vacuumpackaged irradiated pork patties by about 50 and 20%
of the control value at day 5, respectively. Therefore,
the use of antioxidant combinations was more effective
in reducing oxidative changes in aerobically packaged
than vacuum-packaged irradiated pork patties.
4
K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 1–8
Table 1
TBARS values of nonirradiated and irradiated pork homogenates treated with different antioxidants during storage at 4 Ca
Antioxidantb
Control
Gallate
Tocopherol
Trolox
Sesamol
Carnosine
SEM
Day 0 (mg MDA/4 l meat homogenate)
Day 5 (mg MDA/4 l meat homogenate)
Non
Irradiatedc
SEM
Non
Irradiated
SEM
0.12by
0.12by
0.12by
0.12by
0.13by
0.20ay
0.01
0.99ax
0.64bx
0.73bx
0.58bx
0.58bx
1.07ax
0.04
0.05
0.01
0.02
0.01
0.02
0.03
0.12y
0.18
0.12y
0.18y
0.18y
0.18y
0.04
1.52ax
0.68c
0.94bx
0.42dx
0.42dx
1.50ax
0.02
0.01
0.07
0.01
0.01
0.01
0.01
a
Mean values with different letters within a column are significantly different (P< 0.05), n=4. Mean values with different letters within a row
with same storage are significantly different (P<0.05).
b
200 mM of antioxidant concentration.
c
Irradiated at 4.5 kGy.
Table 2
TBARS values of nonirradiated and irradiated pork homogenates treated with different antioxidant combinations during storage at 4 Ca
Antioxidantb
Control
Sd+Ge
G+Tf
S+T
S+Eg
T+E
S+E+T
S+E+G
SEM
Day 0 (mg MDA/4 l meat homogenate)
Non
Irradiated
0.37by
0.36by
0.44ay
0.36by
0.37by
0.38ay
0.36by
0.40aby
0.01
0.79ax
0.64bx
0.70bx
0.65bx
0.65bx
0.63bx
0.66bx
0.63bx
0.02
c
Day 5 (mg MDA/4 l meat homogenate)
SEM
Non
Irradiated
SEM
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.33y
0.34y
0.35y
0.29y
0.34y
0.33y
0.35y
0.32y
0.01
0.89ax
0.61bx
0.59bcx
0.56bcx
0.47dx
0.48dx
0.53cdx
0.53cdx
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
a
Mean values with different letters within a column are significantly different (P <0.05), n=4. Mean values with different letters within a row
with same storage are significantly different (P<0.05).
b
100 mM for each of 2-antioxidants or 66.7 mM for each of 3-antioxidants.
c
Irradiated at 4.5 kGy.
d
Sesamol.
e
Gallate.
f
Trolox.
g
Tocopherol.
3.2. Volatile compounds
Irradiation and antioxidants affected the volatiles of
pork homogenates qualitatively as well as quantitatively
(Table 4). In nonirradiated pork homogenates, antioxidant or antioxidants combination showed little effect
on the production of volatiles because only a few volatiles
were detected. On the other hand, irradiation produced
many new volatiles, mostly aldehydes (propanal, 2methylpropanal, 3-methylbutanal, 2-methylbutanal, pentanal, and hexanal) and S-containing compounds (methanethiol, dimethyl sulfide, and dimethyl disulfide).
Irradiated pork homogenates treated with antioxidants
produced less aldehydes and S-containing volatiles than
the control. Ahn et al. (2000) reported that dimethyl disulfide was a major sulfur compound responsible for the
irradiation off-odor. Gallate, tocopherol, and sesamol
were effective in reducing the off-odor volatiles produced
by irradiation, but sesamol was the most effective among
them. Sesamol reduced the amounts of dimethyl disulfide
and total volatiles by 48 and 43% of the control values,
respectively. Sesamol was effective in reducing the generation of volatiles in irradiated pork during the 7 days of
storage (Chen et al. 1999). Despite the fact that carnosine is known as an antioxidant in meats (Chan & Decker,
1993; Lee, Hendricks & Cornforth, 1999), it did not show
any antioxidant or volatiles-reducing activities in irradiated pork homogenates. The small antioxidant effect of
carnosine is possibly because the added amount of carnosine (200 mM) was so small. Carnosine concentrations in
beef, pork, chicken and fish range from 10–70 mM
(Plowman & Close, 1988). Therefore, carnosine would
not be economical as an antioxidant in reducing lipid
oxidation or off-odor production in irradiated meat.
5
K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 1–8
Table 3
TBARS values of nonirradiated and irradiated pork patties treated with different antioxidant combinations during storage at 4 Ca
Antioxidantb
Day 0 (mg MDA/kg meat)
Day 5 (mg MDA/kg meat)
Non
Irradiatedc
SEM
Non
Irradiated
SEM
Aerobic packaging
Control
Sd+Ge
S+Tf
S+Eg
SEM
0.33a
0.20b
0.18b
0.19b
0.03
0.32a
0.27ab
0.26ab
0.22b
0.03
0.05
0.02
0.02
0.02
0.55ay
0.26by
0.29by
0.27by
0.06
0.74ax
0.37bx
0.37bx
0.35bx
0.06
0.06
0.02
0.02
0.02
Vacuum-packaging
Control
S+G
S+T
S+E
SEM
0.20
0.14
0.16y
0.14
0.02
0.23
0.19
0.21x
0.19
0.01
0.01
0.01
0.01
0.01
0.28ay
0.20by
0.24by
0.23by
0.02
0.42ax
0.34bx
0.34bx
0.35bx
0.03
0.02
0.02
0.02
0.02
a
Mean values with different letters within a column with same packaging are significantly different (P <0.05), n=4. Mean values with different
letters within a row with same storage are significantly different (P< 0.05).
b
100 mM for each of 2-antioxidants.
c
Irradiated at 4.5 kGy.
d
Sesamol.
e
Gallate.
f
Trolox.
g
Tocopherol.
Table 4
Volatile compounds of nonirradiated and irradiated pork homogenates treated with different antioxidant (200 mM)a
Volatiles
Nonirradiated
Acetaldehyde
Pentane
2-Propanone
Carbon disulfide
Hexane
Total volatiles
Irradiated at 4.5 kGy
2-Methyl-1-propene
Acetaldehyde
Methanethiol
Pentane
Propanal
Dimethyl sulfide
Carbon disulfide
2-Methylpropanal
Hexane
3-Methylbutanal
2-Methylbutanal
Heptane
Pentanal
Dimethyl disulfide
Octane
Hexanal
Total volatiles
a
Total ion counts 104
Control
Gallate
Tocopherol
71
53
0
3632bc
326a
4083ab
0
18
0
4795abc
96b
4910ab
29
0
282
2758c
0c
3071b
0
1091a
578
220
131a
599a
1267b
876a
347d
2083a
1171a
475b
184
3774a
816ab
650
14272
0
48b
0
102
0b
268c
1780b
0b
329d
1336b
836a
429c
29
2330b
518b
0
8007
0
0b
0
85
0b
0d
2995a
371ab
387c
2055a
0b
0e
0
2316b
670ab
0
8880
Trolox
Sesamol
Carnosine
0
24
0
6412a
66b
6503a
18
0
0
5244ab
65b
5328ab
24
44
0
5986ab
135b
6190a
24
20
73
601
32
486
18
0b
788
206
61ab
361b
2504a
0b
404c
1510ab
1079a
499a
50
3275ab
572ab
383
11717
24
400ab
182
100
29b
323b
1877b
0b
428b
1180b
937a
209d
15
1965c
440b
0
8112
32
217b
175
272
31b
617a
1603b
232ab
496a
1609ab
1061a
472b
35
3998a
930a
239
12023
18
183
412
118
28
24
177
95
6
153
94
4
41
377
90
217
2036
Mean values with different letters within a row are significantly different (P<0.05), n=4.
SEM
6
K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 1–8
Synergistic effects by antioxidant combinations in
reducing the production of off-odor volatiles by irradiation were found in pork homogenates (Table 5).
Antioxidant combinations decreased the amounts of
aldehydes and S-compounds in irradiated pork homogenates. But the synergistic effects of 3-antioxidant
combinations were not higher than those of 2-antioxidant combinations. Among the antioxidant combinations, sesamol plus gallate, sesamol plus Trolox, and
sesamol plus tocopherol were the most effective in
reducing aldehydes and S-compounds in irradiated pork
homogenates. Sesamol plus Trolox treatments had the
lowest amount of dimethyl disulfide, which was about
50% of the control. Sesamol plus tocopherol was the
most effective in reducing carbon disulfide, 3-methylbutanal, and total volatiles production. The amount of carbon disulfide, a main volatile compound in nonirradiated
pork homogenates, decreased dramatically after irradiation. The result suggested that carbon disulfide could be
a precursor or an intermediate of S-compounds responsible for off-odor in irradiated pork homogenates.
Antioxidant and packaging affected the volatiles of
nonirradiated pork patties (Table 6). All antioxidant
combinations added to pork patties reduced the
amounts of volatiles by about 40% of the control. Pork
patties with added sesamol plus gallate, or sesamol plus
Trolox had lower total volatiles than sesamol plus
tocopherol in aerobically packaged pork, but there was
little difference in S- volatiles that affect irradiation offodor the most. Much greater amounts of volatiles were
found in vacuum-packaged than aerobically packaged
pork patties. All antioxidant combinations decreased
the production of 2-propanone and carbon disulfide in
pork patties. The differences among antioxidant combinations, however, were not significant.
Irradiation not only increased the amounts of volatiles found in nonirradiated pork patties but also produced a few volatiles not found in nonirradiated pork
(Table 7). Acetaldehyde, pentane, 2-propanone, carbon
disulfide, and dimethyl disulfide were the major volatiles
produced in irradiated pork patties. The amounts of
these volatiles were much higher in vacuum-packaged
than aerobically packaged pork patties. The result
shows that S-compounds produced by irradiation volatilized rapidly under aerobic packaging conditions. The
addition of antioxidant combinations decreased the
Table 5
Volatile compounds of irradiated and nonirradiated pork homogenates treated with different antioxidant combination (final 200 mM)a
Volatiles
Total ion counts104
Control
Sb+Gc
G+Td
S+T
S+Ee
T+E
S+E+T
S+E+G
SEM
Nonirradiated
Acetaldehyde
Pentane
2-Propanone
Carbon disulfide
Hexane
Total volatiles
71
53
0
3632b
326
4083b
31
0
0
7780a
146
7958a
90
20
229
7297a
211
7849a
159
20
445
7361a
143
8129a
0
0
216
7708a
5
7929a
0
0
375
4596ab
0
4972b
29
0
91
3679b
0
3799b
32
0
220
3622b
0
3875b
36
14
198
372
74
695
Irradiated at 4.5 kGy
2-Methyl-1-propene
Butane
Acetaldehyde
Methanethiol
Pentane
Propanal
Dimethyl sulfide
Carbon disulfide
2-Methylpropanal
Hexane
3-Methylbutanal
2-Methylbutanal
Heptane
Pentanal
Dimethyl disulfide
Octane
Hexanal
Total volatiles
0
0
1091a
578a
220
131
599a
1267b
876a
347ab
2083a
1176a
475a
184a
3774a
816
650
14272
46
23
30b
209a
222
0
596a
2175ab
204b
435ab
1241b
903b
298c
0b
2168b
775
29
9360
42
0
90b
149ab
178
0
511a
2346a
754a
411ab
1303b
857b
444ab
45b
2238b
774
131
10273
21
21
49b
43ab
187
0
605a
2755a
436ab
426ab
1229b
522c
428ab
17b
1862b
758
147
9513
12
28
155b
0b
116
47
390b
2606a
222b
307b
924c
0d
0d
0b
2124b
643
0
7579
14
25
45b
0b
214
30
576a
2590a
149b
434ab
1621b
660bc
0d
0b
2394b
677
95
9519
19
28
105b
0b
222
0
576a
2117ab
323ab
478a
1261b
0d
420ab
0b
2258b
768
85
8665
22
0
108b
0b
213
0
593a
2806a
420ab
481a
1598b
621bc
351c
0b
2052b
557
118
8945
19
20
193
54
121
50
32
273
80
33
228
72
26
31
297
81
171
1780
a
b
c
d
e
Mean values with different letters within a row are significantly different (P<0.05), n=4.
Sesamol.
Gallate.
Trolox.
Tocopherol.
7
K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 1–8
Table 6
Volatile compounds of nonirradiated pork patties treated with different antioxidant combination (final 200 mM) and packaging conditiona
Volatiles
Total ion counts 104
Aerobic packaging
2-Methylbutane
Pentane
Ethanol
2-Propanone
Dimethyl sulfide
Carbon disulfide
1-Hexene
Hexane
2-Hexene
2-Butanone
3-Methylbutanal
Heptane
2-Pentanone
Total volatiles
a
b
c
d
e
Vacuum-packaging
Control
Sb+Gc
S+Td
S+Ee
SEM
Control
S+G
S+T
S+E
SEM
34b
606a
1458ab
366
119c
391
0
684
0
71a
94a
40
126a
3793a
31b
341b
902b
191
251a
313
0
683
0
0b
50b
18
46b
2830b
43a
262b
794b
110
175b
323
0
636
0
0b
73a
44
0c
2461b
38ab
310b
2056a
309
190b
330
0
689
0
0b
0c
97
0c
4223a
2
58
221
76
17
31
–
67
–
15
18
52
18
290
295a
1840a
1865
4429a
388
1037a
57a
509
18
79a
35
220a
50
10826a
94bc
1082b
1126
1852b
370
620b
0b
474
0
0b
0
158b
0
5778bc
193ab
681b
1232
2966b
405
365b
0b
548
0
63a
50
147b
69
6723b
20c
732b
1703
473c
451
344b
0b
409
0
0b
30
132b
0
4296c
13
176
250
380
73
69
4
65
9
11
27
22
21
540
Mean values with different letters within a row are significantly different (P<0.05), n=4.
Sesamol.
Gallate.
Trolox.
Tocopherol.
Table 7
Volatiles of irradiated (4.5 kGy) pork patties treated with different antioxidant combination (final 200 mM) and packaging conditiona
Volatiles
Total ion counts 104
Aerobic packaging
2-Methylpropane
2-Methyl-1-propene
Butane
Acetaldehyde
1-Butene
2-Methyl-2-butene
2-Methylbutane
1-Pentene
Pentane
Ethanol
2-Propanone
Dimethyl sulfide
Carbon disulfide
1-Hexene
Hexane
2-Hexene
2-Butanone
Heptane
Dimethyl disulfide
Total volatiles
a
b
c
d
e
Vacuum packaging
Control
Sb+Gc
S+Td
S+Ee
SEM
Control
S+G
S+T
S+E
SEM
199b
641b
860b
520a
345
0
216
281
3467a
435
5379a
1007a
453
167
300
0
82
45
1056a
15024a
201b
767b
843b
0b
378
0
188
323
1422b
222
1954b
511b
644
145
270
0
0
40
246b
7939c
191b
1183a
1199ab
103b
329
0
166
401
1341b
215
1004b
608b
390
175
305
0
0
0
78b
7478c
310a
1286a
1421a
395a
538
0
398
341
994b
291
2889b
899a
623
254
244
0
135
137
183b
11053b
11
131
101
78
63
–
59
64
323
65
518
93
109
49
58
–
62
72
183
765
242b
1523b
1587
1111a
973b
134
252ab
453
1762a
1949
4135a
4100a
2596a
293b
593a
164ab
130
270b
4791a
25897a
291b
2030a
1649
455b
1512a
49
112b
428
1174b
788
2035b
1937b
1100b
197c
491ab
55b
0
261b
917b
14699b
349b
2086a
1768
372b
1443a
125
129b
368
1107b
856
2028b
2244b
1188b
400a
272b
37b
30
273b
1513b
16015b
1096a
2382a
1877
492b
1463a
114
425a
359
1185b
833
3848a
3653a
1009b
374ab
758a
188a
27
878a
4668a
24804a
52
122
223
112
115
34
30
38
99
215
423
336
330
26
84
34
68
54
375
1410
Mean values with different letters within a row are significantly different (P< 0.05), n=4.
Sesamol.
Gallate.
Trolox.
Tocopherol.
8
K.C. Nam, D.U. Ahn / Meat Science 63 (2003) 1–8
production of these volatiles as well as total volatiles in
pork patties. In aerobically packaged pork patties, most
antioxidant combinations were effective in reducing the
amounts of S-compounds such as carbon disulfide and
dimethyl disulfide, which contribute the characteristic
off-odor of irradiated meats. However, no significant
differences on the production of carbon disulfide and
dimethyl disulfide among the antioxidant combinations
were found in aerobically packaged pork patties. Higher
amounts of volatiles were found in vacuum-packaged
pork patties than aerobically packaged patties. The
addition of sesamol plus gallate (final 200 mM) to
vacuum-packaged irradiated pork patties reduced acetaldehyde, carbon disulfide, dimethyl sulfide, dimethyl
disulfide, and total volatiles by 59, 53, 58, 81, and 43%
of the control, respectively.
4. Conclusion
The addition of antioxidant combinations using
sesamol, gallate, and a-tocopherol to a final concentration of 200 mM was effective in reducing lipid
oxidation and off-odor volatiles in irradiated pork
patties. Antioxidant combinations reduced the S-containing volatiles, which are the main off-odor compounds in irradiated, vacuum-packaged pork patties.
Treatments containing a combination of antioxidants
also controlled lipid oxidation in aerobically packaged
irradiated pork patties. Therefore, modification of the
packaging method with addition of antioxidants will be
a key to solve the off-odor problems in the storage of
irradiated pork patties.
Acknowledgements
This project, No. 3706, was funded by National Pork
Producers Council, on behalf of the Iowa pork Producers Association.
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