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Grapefruit and lemon were exposed to phytosanitary irradiation doses of 0, 0.4, and 1 kGy, and then electronic-sensing screening of irradiation status and identification of radiation-induced ESR markers were conducted during 20 days storage. Codex standard photostimulated luminescence measurement (PSL(1)) was not a reliable indicator of irradiation status. Electronic tongue and electronic nose, however, showed potential as screening tools for discriminating irradiated fruits from non-irradiated counterparts based on principal component analysis of taste attributes and flavor patterns. Calibrated PSL approach clearly distinguished irradiated from non-irradiated samples based on the PSL ratio (PSL(2)/PSL(1)). Verification of irradiation status by electron spin resonance spectroscopy revealed clear paramagnetic centers from both irradiated fruits samples and ethanol-vacuum drying pretreatment improved radiation-induced ESR signal detection; not prominent enough in 0.4 kGy-irradiated commodities during 20 days of storage. Peel parts of both fruits showed high limonene which proportionally increased with irradiation doses (p

The aim of this study was to evaluate the effects of different irradiation doses (0–4.5 kGy) on the quality of raw ground beef. The results showed a significant increase in lipid oxidation and protein oxidation after irradiation, and color fading was observed only at 4.5 kGy irradiation. The increasing spermidine did not trigger any food safety panic button in irradiated raw ground beef, but this issue should be taken into consideration in irradiated cured meat products. Electronic tongue detected higher saltiness in irradiated meat due to increased drip loss by irradiation. Due to the synergistic effect of saltiness on umami, an unexpected increase in umami taste was observed at 4.5 kGy. Dimethyl disulfide produced from the sulfur-containing amino acids, the major irradiation processing biomarker, was only detected at 4.5 kGy irradiation. Thus, electron beam irradiation

The objective of this study was to elucidate the relationships among lipid/protein oxidation, color changes, off-taste, and off-odor in irradiated raw beef. The raw beef round eye was prepared and irradiated at 0, 1.5, 3.0, and 4.5 kGy using a linear accelerator. Significant increases in lipid oxidation and protein oxidation were found in irradiated raw beef, while significant decreases were observed in the color values (L*-, a*-, and b*-value). The degradation of nucleotides can contribute to the taste changes (increase in sourness and decrease in umami taste) in the irradiated raw beef, which was further confirmed by the electronic tongue data. The sulfur volatiles (e.g.: dimethyl disulfide) from the sulfur-containing amino acids increased significantly after irradiation, indicating these are closely related to the off-odor of irradiated beef.

Korean citrus fruits (Jinjihyang and Chunggyun) were treated with electron beam (e-beam) at phytosanitary irradiation doses of 0, 0.4, and 1 kGy, and their irradiation status was screened after storage for 0, 10, and 20 days. Because of the inherent limitations of photo-stimulated luminescence (PSL), the first PSL measurement (PSL1) was not sufficient to distinguish the irradiated samples from the non-irradiated controls. The calibrated PSL approach clearly distinguished the e-beam-irradiated samples from the control based on PSL ratio (PSL2/PSL1): > 10, non-irradiated

The objective of this study was to elucidate the relationships among lipid/protein oxidation, color changes, off-taste and off-odor in irradiated raw beef round eye. Raw beef round eye was prepared and irradiated at 0, 1.5, 3.0 and 4.5 kGy using a linear accelerator. Significant increases in lipid oxidation and protein oxidation were found in irradiated raw beef round eye, while significant decreases were observed in the color values (L*-, a*-, and b*-value). The degradation of nucleotides can contribute to the taste changes (increase in sourness and decrease in umami taste) in the irradiated raw beef round eye, which was further confirmed by the electronic tongue data. The sulfur volatiles (e.g.: dimethyl disulfide) from the sulfur-containing amino acids increased significantly after irradiation, indicating these are closely related to the off-odor of irradiated beef round eye.

This study was designed to elucidate the mechanisms of quality changes in raw turkey breast meat by irradiation. Raw turkey breast meat was irradiated at 0 kGy, 1.5 kGy, 3.0 kGy and 4.5 kGy, and changes in quality parameters including color, lipid and protein oxidation, and off-odor volatiles were determined. Irradiation accelerated lipid and protein oxidation, and increased redness in raw turkey breast meat. However, irradiation had less effect on the volatile profiles of salt-soluble muscle extract than water-soluble muscle extract because the primary radiolytic product from water (hydroxyl radical) had higher chances to react with the water-soluble molecules nearby. The radiolytic degradation products from sulfur-containing amino acids and aldehydes from lipid oxidation were two major volatile compounds responsible for the off-odor of irradiated raw turkey breast meat. Dimethyl disulfide was found only in irradiated raw turkey breast meat, and the amount of dimethyl disulfide linearly increased as the irradiation dose increased, indicating that this compound can be used as a marker for irradiate meat.

Proteins and its constituents (amino acids) are known as the major contributors to the off-odor in irradiated meat. However, radiolytic degradation of amino acids occurred not only at side chains but also at amino- and carboxyl-groups of the α-carbon. A model system with amino acid esters was used to elucidate the mechanisms of volatile production at side chains of amino acids by irradiation. The low-molecular weight aldehydes, which contributed to the irradiation off-odor, were mainly from acidic, aliphatic and aliphatic hydroxyl group amino acid esters through the radiolysis of amino acid side chains or Strecker degradation. However, the contribution from non-sulfur amino acids was minor compared with sulfur amino acids. Among the sulfur-containing amino acids, methionine made the greatest contribution to the irradiation off-odor not only through the direct cleavage of the side chain. However, the chemical reactions of sulfur compounds with other compounds produced by irradiation also played significant roles to the off-odor of irradiated meat.

7.1 Food Irradiation 156 7.1.1 History of Food Irradiation 156 7.1.2 Irradiation Process 159 7.2 Microbial Decontamination of Meat by Irradiation 162 7.2.1 Factors Affecting Radiation Destruction of Micro-Organisms in Meat 163 7.2.1.1 Irradiation Dose 163 7.2.1.2 Meat Composition 163 7.2.1.3 Temperature 164 7.2.1.4 Gaseous Composition 164 7.2.1.5 Microbial Factors 165 7.2.2 Combinations of Irradiation and Other Antimicrobial Interventions 166 7.3 Quality Changes in Meat by Irradiation 167 7.3.1 Lipid Oxidation 167 7.3.2 Sources and Mechanisms of Off-Odor Production 169 7.3.2.1 Sources of Off-Odor Production in Irradiated Meat........ 169 7.3.2.2 Mechanism of Off-Odor Production in Irradiated Meat.....170 7.3.3 Color Changes in Meat by Irradiation 171 7.3.3.1 Color Changes in Irradiated Raw and Cooked Meat ...... 171 7.3.3.2 Mechanism of Color Changes in Irradiated Meat 173 7.3.4 Water Holding Capacity and Texture 175 7.3.5 Consumer Attitude and Acceptance of Irradiated Meat 175 7.3.6 Control of Quality Changes 176 7.3.6.1 Additives 176 7.3.6.2 Packaging 178 7.3.6.3 Packaging and Additive Combinations 180 7.4 Future Research Needed 180 References 181 DK3813.book Page 155 Friday, February 10, 2006 10:33 AM

The objective of this study was to evaluate the effect of irradiation on lipid/protein oxidation, color changes, and off-odor volatiles production in uncured and cured cooked turkey meat products. Uncured cooked turkey breast meat and cured commercial turkey breast rolls and ham were prepared and irradiated at 0, 1.5, 3.0, and 4.5 kGy using a linear accelerator. The results showed that irradiation had little effects on lipid oxidation of cured cooked turkey products, but accelerated lipid oxidation in uncured cooked turkey breast meat (P < 0.05). Protein oxidation was increased both in cured and uncured meats (P < 0.05), but more in cured cooked meat by irradiation. The redness of uncured cooked turkey was increased (P < 0.05), but the redness of cured cooked turkey meat was faded by irradiation (P < 0.05). Irradiated cured cooked turkey meat products produced less off-odor volatile compounds (dimethyl disulfide, 3-methyl/2-methyl-butananl, and hexanal) than irradiated uncured cooked meat products due to various additives in the cured meat products. Our results suggested that irradiation resulted in different chemical reactions to pigments in uncured and cured cooked turkey meat products, but cured cooked turkey meat products have a higher tolerance to odor deterioration than uncured cooked turkey meat products.

High-dose (higher than 30 kGy) irradiation has been used to sterilize specific-purposed foods for safe and long-term storage. The objective of this study was to investigate the effect of high-dose irradiation on the quality characteristics of ready-to-eat chicken breast in comparison with those of the low-dose irradiation. Ready-to-eat chicken breast was manufactured, vacuum-packaged, and irradiated at 0, 5, and 40 kGy. The populations of total aerobic bacteria were 4.75 and 2.26 Log CFU/g in the samples irradiated at 0 and 5 kGy, respectively. However, no viable cells were detected in the samples irradiated at 40 kGy. On day 10, bacteria were not detected in the samples irradiated at 40 kGy but the number of bacteria in the samples irradiated at 5 kGy was increased. The pH at day 0 was higher in the samples irradiated at 40 kGy than those at 0 and 5 kGy. The 2-thiobarbituric acid reactive substance (TBARS) values of the samples were not significantly different on day 0. However, on day 10, the TBARS value was significantly higher in the samples irradiated at 40 kGy than those at 0 and 5 kGy. There was no difference in the sensory scores of the samples, except for off-flavor, which was stronger in samples irradiated at 5 and 40 kGy than control. However, no difference in off-flavor between the irradiated ones was observed. After 10 days of storage, only the samples irradiated at 40 kGy showed higher off-flavor score. SPME-GC–MS analysis revealed that 5 kGy of irradiation produced 2-methylbutanal and 3-methylbutanal, which were not present in the control, whereas 40 kGy of irradiation produced hexane, heptane, pentanal, dimethly disulfide, heptanal, and nonanal, which were not detected in the control or the samples irradiated at 5 kGy. However, the amount of compounds such as allyl sulfide and diallyl disulfide decreased significantly in the samples irradiated at 5 kGy and 40 kGy.

Irradiation is the most efficient non-thermal technology for improving hygienic quality and extending the shelf-life of food products. One of the adverse effects of food irradiation, however, is off-flavor production, which significantly affects the sensory preferences for certain foods. In this study, garlic (5%, w/w) and red wine (1:1, w/w) were added to ground beef to increase the radiation sensitivity of pathogens and improve meat odor/flavor. Samples were irradiated at 0 or 5 kGy in the presence of charcoal pack. SPME-GC–MS analysis was performed to measure the changes in the volatile compounds and sensory characteristics of the samples. The amount of total volatile compounds produced from ground beef was greater when the sample was irradiated. When garlic and red wine were added to the ground beef, the amount of volatile compounds significantly increased, and the amount of volatile compounds increased even further after irradiation. However, when the samples were irradiated with charcoal pack, the amount of volatile compounds decreased significantly. Sensory evaluation indicated that charcoal pack significantly increased the odor preferences for both irradiated and non-irradiated ground beef added with garlic. These results indicated that addition of charcoal pack to ground beef could reduce off-odor problems induced by irradiation, and this effect was consistent even when certain additives such as garlic and red wine were added.

The effect of adding 10% fat substitute (10%F) or 2% plum extract (2%P) on the formation of hydrocarbons and 2-alkylcyclobutanones (2-ACBs) in freeze-dried beef patties, irradiated (IR) at 44 kGy, and freeze-dried irradiated cooked beef patties was investigated. Hydrocarbons, such as C16:3, C16:2, C17:2 and C17:1, were detected only in irradiated samples and their concentrations were high in the order of 2%P+IR, IR and 10%F+IR. Only irradiated beef samples produced 2-ACBs (2-DCB, 2-TCB, 2-TeCB), and their amounts were high in reverse order. The addition of fat substitute or plum extract did not help in reducing hydrocarbons and 2-ACBs in the freeze-dried irradiated cooked beef. However, the amounts of radiationinduced hydrocarbons and 2-ACBs in all irradiated beef patties even at 44 kGy were too small to be of concern for human consumption.

Irradiated raw ground beef had lower a*- and b*-values than nonirradiated ones regardless of garlic or onion treatment at 0 d. Irradiation increased TBARS values of control ground beef, but addition of 0.5% onion or 0.1% garlic+0.5% onion reduced oxidative changes during storage. Addition of garlic or onion greatly increased the amounts of sulfur compounds, but the increase was greater with garlic. With irradiation, the profiles and amounts of S-volatiles in raw ground beef changed significantly. However, the intensity of irradiation aroma in irradiated raw ground beef with garlic or onion was similar to that of the nonirradiated control. This indicated that some of the sulfur compounds unique to garlic or onion interacted with common sulfur compounds detected in irradiated meat and masked or changed the odor characteristics of irradiated raw ground beef. It was concluded that >0.5% onion or

Addition of 0.5% onion was effective in reducing lipid oxidation in irradiated cooked ground beef after 7 day storage. Addition of garlic or onion greatly increased the amounts of sulfur volatiles from cooked ground beef. Irradiation and storage both changed the amounts and compositions of sulfur compounds in both garlic- and onion-added cooked ground beef significantly. Although, addition of garlic and onion produced large amounts of sulfur compounds, the intensity of irradiation odor and irradiation flavor in irradiated cooked ground beef was similar to that of the nonirradiated control. Addition of garlic (0.1%) or onion (0.5%) to ground beef produced a garlic/onion aroma and flavor after cooking, and the intensity was stronger with 0.1% garlic than 0.5% onion treatment. Considering the sensory results and the amounts of sulfur compounds produced in cooked ground beef with added garlic or onion, 0.5% of onion or less than 0.1% of garlic is recommended to mask or change irradiation off-odor and off-flavor.

Four antioxidant treatments (none, 0.05% ascorbic acid, 0.01%alpha-tocopherol + 0.01% sesamol, and 0.05% ascorbic acid + 0.01%alpha-tocopherol + 0.01% sesamol) were applied to ground beef using either mixing or spraying method. The meat samples were placed on Styrofoam trays, irradiated at 0 or 2.5 kGy, and then stored for 7 d at 4 degrees C. Color, lipid oxidation, volatiles, oxidation-reduction potential (ORP), and carbon monoxide (CO) production were determined at 0, 3, and 7 d of storage. Irradiation increased lipid oxidation of ground beef with control and ascorbic acid treatments after 3 d of storage. alpha-Tocopherol + sesamol and ascorbic acid +alpha-tocopherol + sesamol treatments were effective in slowing down lipid oxidation in ground beef during storage regardless of application methods, but mixing was better than the spraying method. Irradiation lowered L*-value and a*-value of ground beef. Storage had no effect on lightness but redness decreased with storage. Ascorbic acid was the most effective in maintaining redness of ground beef followed by ascorbic acid +alpha-tocopherol + sesamol. Irradiation and storage reduced the b*-value of ground beef. Irradiation lowered ORP of ground beef regardless of antioxidants application methods, but ORP was lower in beef with mixing than spraying method. Beef sprayed with antioxidants produced more hydrocarbons and alcohols than the mixing application, but ascorbic acid +alpha-tocopherol + sesamol treatment was effective in reducing the amount of volatiles produced by irradiation. Therefore, mixing was better than the spraying method in preventing lipid oxidation and maintaining color of irradiated ground beef.

The effect of electron beam irradiation on the survival and growth of Listeria monocytogenes and natural microflora in oven-roasted turkey breast rolls and turkey hams was evaluated. Slices of turkey breast rolls and hams were inoculated with a 5-strain mixture of L. monocytogenes to achieve 10 6 to 10 7 cfu/ cm 2 ; vacuum-packaged; irradiated at 0 (control), 1.0, 1.5, 2.0, or 2.5 kGy; and stored at 4°C for up to 28 d. Numbers of naturally occurring bacteria on sliced turkey hams and breast rolls were 2.72 and 6.22 log 10 cfu/ cm 2 , respectively. The values of the radiation dose that results in 90% reduction of viable L. monocytogenes in breast rolls and hams were 0.52 and 0.47 kGy, respectively. For breast rolls, the log 10 reductions of L. monocytogenes after irradiation at 1.0 and 2.5 kGy were 1.5 and 4.7, respectively, whereas they were 2.0 and 5.5 for hams. The log 10 reductions of aerobic plate count (APC) in breast rolls after 1.0 and 2.0 kGy of irradiation were 2.9 and 5.2, whereas that of hams was

Irradiation and storage increased lipid oxidation of normal and pale-soft-exudative (PSE) muscles, whereas dark-firm-dry (DFD) muscle was very stable and resistant to oxidative changes. Irradiation increased redness regardless of pork-quality type, and the increases were proportional to irradiation dose. Irradiation increased the production of sulfur-containing volatiles, but not lipid oxidation products. The total volatiles produced in normal and PSE pork were higher than the DFD pork. Some volatiles produced in meat by irradiation evaporated during storage under aerobic packaging conditions. Nonirradiated normal and DFD pork had higher odor preference scores than the nonirradiated PSE, but irradiation reduced the preference scores of all 3 pork-quality types. Cette etude determine et compare les effets d'une irradiation sur l'oxydation lipidique, les composes volatils indesirables et la couleur de viande de porc normale, pâle, molle et exsudative (PSE) et sombre, ferme et seche (DFD), emballee en aerobie, pendant un entreposage frigorifique. La viande de porc DFD, generalement peu utilisee a cause de sa sensibilite microbienne, est plus stable et resistante a l'oxydation lipidique causee par l'irradiation que la viande normale.

Lipid oxidation, color, and volatiles of double-packaged pork loins with various oleoresin or oleoresin–tocopherol combinations were determined to establish the best oleoresin–tocopherol conditions that can improve the quality of irradiated raw and cooked pork loins. Rosemary and α-tocopherol combination at 0.05% and 0.02% of meat weight, respectively, showed the most potent antioxidant effects in reducing both TBARS values and the amounts of volatile aldehydes in irradiated raw and cooked pork loins. The antioxidant combination, however, did not affect the production of sulfur volatiles responsible for irradiation off-odor and showed little effects on color changes in irradiated raw and cooked pork loins. Exposing double-packaged irradiated pork to aerobic conditions for 3 days during the 10-day storage was effective in controlling both lipid oxidation and irradiation off-odor, regardless of packaging sequences.

Patties were prepared using the breast meat from 15-wk-old turkeys fed one of the 8 dietary treatments [Con, control; VE, 200 IU/kg vitamin E; Se, 0.3 mg/kg selenium; CLA, 2.5% conjugated linoleic acids; VE + Se, 200 IU/kg vitamin E + 0.3 mg/kg selenium; VE + CLA, 200 IU/kg vitamin E + 2.5% CLA; Se + CLA, 0.3 mg/kg selenium + 2.5% CLA; VE + Se + CLA, 200 IU/kg vitamin E + 0.3 mg/kg selenium + 2.5% CLA] for 4 wk. Patties were vacuum-packaged in oxygen-impermeable bags, and then irradiated with 0 or 1.5 kGy. Irradiated breast meats were cooked and vacuum-packaged or aerobically packaged, and the quality of meat was evaluated after 0 and 7 d of storage at 4 °C. Dietary VE + Se, VE + CLA, Se + CLA, and VE + Se + CLA treatments reduced lipid oxidation of cooked irradiated (1.5 kGy) turkey breast meat by 24%, 29%, 26%, and 40%, respectively, compared to that of the control after 7 d of storage under aerobic conditions. Dietary treatments had no influences on the color of nonirradiated cooked turkey breast. However, dietary VE and Se decreased the internal a* value of irradiated meats in vacuum packaging at days 0 and 7, and the effect was even greater when VE and Se were combined with CLA. Dietary VE, Se, and CLA combinations significantly reduced the production of volatiles, especially those related to lipid oxidation. Dietary VE + Se, VE + CLA, and VE + Se + CLA reduced the difference in sulfur-containing compounds between irradiated and nonirradiated meat. Aerobic packaging was more effective than vacuum packaging in reducing sulfur-containing compounds. Therefore, dietary VE, Se, and CLA combinations plus aerobic packaging were effective in reducing the odor problems induced by irradiation.

Irradiated restructured pork loins treated with rosemary–tocopherol/double-packaging had lower TBARS values than vacuum-packaged control after 10 days of refrigerated storage. The rosemary–tocopherol combination, however, had no effect on the production of sulfur volatiles responsible for the irradiation off-odor, and color changes in irradiated pork. V7/A3 double-packaging was effective in reducing the sulfur volatiles significantly. Rosemary–tocopherol combination was highly effective in reducing the volatile hexanal in irradiated restructure pork. Irradiation was effective in reducing Listeria monocytogenes and Salmonella typhimurium inoculated on the surface of restructured pork loin in dose-dependent manner. The irradiation D10 values for L. monocytogenes and S. typhimurium were 0.58 and 0.55 kGy, respectively. During the 20 days of refrigerated storage, L. monocytogenes in both nonirradiated and irradiated samples grew gradually, but the number of S. typhimurium decreased. The added rosemary–tocopherol, however, showed little bacteriocidal effects to L. monocytogenes and S. typhimurium. � 2006 Elsevier Ltd. All rights reserved.

Lipid oxidation, color, volatiles, and sensory evaluation of double-packaged pork loin were determined to establish a modified packaging method that can improve the quality of irradiated pork loins. Vacuum-packaged irradiated samples produced dimethyl sulfide and dimethyl disulfide responsible for irradiation off-odor, whereas lipid oxidation was promoted under aerobic conditions. Exposing double-packaged irradiated pork to aerobic conditions for 1 to 3 d was effective in controlling both lipid oxidation and irradiation off-odor, regardless of packaging sequence. Sensory panels could distinguish the decrease in irradiation off-odor intensities by modifying the packaging method. However, carbon monoxide heme pigments, responsible for the increased redness by irradiation, were not effectively controlled by double packaging alone.

*/ */ * ratios on day 7 compared with day 0 for * ratios on day 7 compared with day 0 for * ratios on day 7 compared with day 0 for * ratios on day 7 compared with day 0 for the 4.5-kGy treatment. Oxidation-reduction potential was decreased on day 0 and day 7 for the vacuum-packthe 4.5-kGy treatment. Oxidation-reduction potential was decreased on day 0 and day 7 for the vacuum-packthe 4.5-kGy treatment. Oxidation-reduction potential was decreased on day 0 and day 7 for the vacuum-packthe 4.5-kGy treatment. Oxidation-reduction potential was decreased on day 0 and day 7 for the vacuum-packthe 4.5-kGy treatment. Oxidation-reduction potential was decreased on day 0 and day 7 for the vacuum-packaged treatment that was irradiated at 4.5 kGy compared with the 0-kGy treatment. aged treatment that was irradiated at 4.5 kGy compared with the 0-kGy treatment. aged treatment that was irradiated at 4.5 kGy compared with the 0-kGy treatment. aged treatment that was irradiated at 4.5 kGy compared with the 0-kGy treatment. aged treatment that was irradiated at 4.5 kGy compared with the 0-kGy treatment. K K K Keywor eywor eywor eywords: irr ds: irr ds: irr ds: irr ds: irradiation, cur adiation, cur adiation, cur adiation, cur adiation, cured color, nitrite, oxidation-reduction potential, ham eduction potential, ham eduction potential, ham eduction potential, ham eduction potential, ham

esulted in the formation of new v of new v of new v of new v of new volatile compounds in the ham samples including heptane olatile compounds in the ham samples including heptane olatile compounds in the ham samples including heptane olatile compounds in the ham samples including heptane olatile compounds in the ham samples including heptane, trans-1-butyl-2-methylcy -1-butyl-2-methylcy -1-butyl-2-methylcy -1-butyl-2-methylcy -1-butyl-2-methylcyclopropanone, 2- octene octene octene octene octene, and toluene , and toluene , and toluene , and toluene , and toluene, which w , which w , which w , which w , which were not pr e not pr e not pr e not pr e not present in nonirr esent in nonirr esent in nonirr esent in nonirr esent in nonirradiated ham. I adiated ham. I adiated ham. I adiated ham. I adiated ham. In the case of fr n the case of fr n the case of fr n the case of fr n the case of frankfurters, irr

There is growing concern that the free radical scavenging effect of antioxidants added to meats might reduce the antimicrobial effectiveness of ionizing radiation. A study was conducted to determine the effect of vitamin E on the behavior (growth) of Listeria monocytogenes and color stability in turkey meat following electron beam irradiation. Raw ground turkey breast meat from birds fed diets containing 0 (control), 50, 100, and 200 IU/kg of vitamin E was inoculated with a five-strain mixture of L. monocytogenes to give approximately 10(7) CFU/g. Inoculated samples were irradiated at 0, 0.5, 1, and 2 kGy and stored aerobically (12 days) or under vacuum (42 days) at 4 degrees C. L. monocytogenes survivors were determined by plating samples on modified Oxford medium and counting colonies on modified Oxford medium plates after 48 h at 35 degrees C. Meat color was measured using a colorimeter. Irradiation at 2.0 kGy resulted in an approximately 3.5-log reduction of initial numbers of L. monocytogenes. There were no significant differences in D-values (decimal reduction times) for L. monocytogenes in meat irrespective of vitamin E treatment (P0.05). Also, vitamin E treatments did not affect growth of the pathogen in aerobic or vacuum-packaged samples following irradiation (P0.05). Compared with controls, irradiated meat from birds fed 100 or 200 IU/kg of vitamin E demonstrated significant improvement in color stability (lightness and redness values) during aerobic storage (P0.05). Dietary vitamin E (100 to 200 IU/kg) has good potential for improving the color stability of turkey meat without compromising the microbial safety of the irradiated product.

To determine the effect of far-infrared (FIR) irradiation on the antioxidant activities of sesame meal, half of sesame seeds were FIR-irradiated and then oil was extracted from the seeds. The resulting defatted sesame meal (DSM) was extracted with methanol, and the antioxidant activities of methanolic extract were determined. FIR irradiation of sesame seeds for 30 min increased the total phenol content from 34.0 to 59.0 muM and radical scavenging activity of DSM extracts from 26.40 to 68.76%. The induction time of lipid oxidation of oil added to extracts was also retarded from 0.82 to 0.96 h. According to the gas chromatography-mass spectrometry analysis, several low molecular weight phenolic compounds, such as p-hydroxy benzoic acid, vanillic acid, p-coumaric acid, isoferulic acid, and o-coumaric acid, were frequently detected in FIR-irradiated DSM extracts as compared to unirradiated ones. These results indicated that FIR irradiation of sesame seeds increased the antioxidant activity of methanolic extracts of DSM.

A comparison of irradiation effects on injected and uninjected fresh pork loin quality was conducted. Sixty pork loins from pigs of similar genetics were obtained from a pork harvesting facility immediately prior to processing. Thirty loins were injected with a brine composed of 2.17% salt/3.04% phosphate/20.8% lactate brine while thirty were not injected. Injected loins were pumped to 13% added weight. Ten loins of each group of thirty were not irradiated while an additional 10 loins were irradiated at 2.2 kGy and the final ten loins were irradiated at 4.4 kGy. Lipid oxidation, color, purge, volatiles, and tenderness were measured on sections of the treated loins after 0, 7, 21, and 35 days of refrigerated storage. Lipid oxidation was minimal for the 0 and the 2.2 kGy-treated loins, but was significantly greater (P

The effects of double packaging on lipid oxidation, color, and volatile production were determined to establish a modified packaging method to improve quality changes in irradiated raw turkey meat. Sliced raw turkey breast and thigh meats were aerobically, vacuum- or double (vacuum and aerobic)-packaged, electron beam irradiated at 2.5 kGy, and then stored under refrigerated temperature. For the double-packaged samples, the outer vacuum bags were removed after 5, 7, or 9 d of refrigerated storage. 2-Thiobarbituric acid-reactive substances (TBARS) values, volatile compounds, and color values of the samples were determined after 10 d of storage. Irradiation and aerobic packaging promoted production of aldehydes (propanal and hexanal) related to lipid oxidation in turkey breast and thigh meats. Vacuum-packaged irradiated samples retained S-volatile compounds (methanethiol, dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide), mainly responsible for the irradiation off-odor, during storage. Exposure of double-packaged irradiated turkey meats to aerobic conditions by removing outer vacuum bags a few days before the test was effective in controlling both lipid oxidation-dependent (aldehydes) and radiolytic off-odor (S-compounds) volatiles. The a* values of raw turkey breast and thigh meats increased by irradiation regardless of packaging conditions. The a* value of double-packaged meats was lower than that of the vacuum-packaged meats but was not significant. Thus, the use of double-packaging alone was not enough to reduce the pink color of irradiated raw turkey meat. When lipid oxidation and irradiation off-odor should be minimized without any additional additives, however, double packaging is an excellent method to be used for turkey meats.

The antioxidant effect of far infrared-treated rice hull (FRH) extracts in irradiated turkey breast meat was compared with that of sesamol and rosemary oleoresin. The FRH extracts significantly decreased thiobarbituric acid-reactive substances values and volatile aldehydes (hexanal, pentanal, and propanal) and was effective in reducing the production of dimethyl disulfide responsible for irradiation off-odor in irradiated raw and cooked turkey meat during aerobic storage. The antioxidant activity of FRH extracts (0.1%, wt/wt) was as effective as that of rosemary oleoresin (0.1%). However, the addition of FRH extracts increased red and yellow color intensities and produced an off-odor characteristic to rice hull in raw and cooked meat.

Antioxidants had no effect on the production of sulfur compounds, color change, and off-odor intensity of irradiated turkey breast meat, but addition of sesamol + tocopherol or gallate + tocopherol was effective in reducing thiobarbituric acid-reactive substance values and aldehydes, especially under aerobic conditions. Consumers preferred the color of irradiated raw and cooked meat to nonirradiated meat because the pink color of irradiated meat looked fresher. The packaging method was more important than the antioxidant treatment in reducing irradiation off-odor because S-compounds produced by irradiation easily volatilized under aerobic packaging conditions. Therefore, the combined use of aerobic packaging and antioxidants is recommended to improve consumer acceptance of irradiated poultry meat.

Beef loins, aged for different lengths of time post slaughter, were treated with ionizing radiation, irradiated ground beef produced volatile sulfur compounds (S-volatiles) responsible for the unique irradiation odor and accelerated lipid oxidation. The quality charges by irradiation became greater as aging and storage time increased. During aerobic storage, the S-volatiles disappeared whereas volatile aldehydes drastically increased in irradiated beef.Addition of ascorhic acid at 0.1% (wt/wt) or sesanol) α-locopherol at each 0.01% level to ground breef before irradiation effectively reduced lipid oxidation and S volatiles. As storage time increased, however, the antioxident effect of sesanol + tocopherol in irradiated ground beef was superior to that of ascorbic acid.

Dietary conjugated linoleic acid (CLA) treatment reduced color a*- and b*-values of cooked chicken breast rolls. Sensory panels rated the color of cooked chicken rolls with CLA treatments darker than the control. The production of carbon monoxide (CO) in cooked chicken rolls increased dramatically after irradiation and was correlated with the increased redness of cooked chicken rolls after irradiation. Consumer test indicated that the color of cooked chicken rolls after irradiation was preferred to the nonirradiated, but no preference for the color among the three CLA treatments was found. Irradiation greatly increased volatile production and induced a metallic off-flavor in chicken rolls. Sensory evaluation indicated that the hardness of chicken rolls increased and juiciness decreased as the dietary level of CLA increased.

To understand the mechanisms of off-odor production in irradiated meat, the volatile compounds produced from individual fatty acids by irradiation were identified. Nonirradiated oil emulsions prepared with polyunsaturated fatty acids (PUFAs) produced many volatile compounds, but the amounts of volatiles generally decreased after irradiation. Although volatile profiles of fatty acid emulsions were changed by irradiation, the odor characteristics and intensity between irradiated and nonirradiated fatty acid emulsions were not different. Thiobarbituric acid-reactive substances (TBARS) values indicated that irradiation accelerated lipid oxidation during subsequent storage, but the volatiles produced by lipid oxidation were not the major contributors of off odor in irradiated samples.

UR STUDIES SHOWED THAT ALL IRRADIATED MEAT PRODUCED characteristic irradiation odor regardless of degree of lipid oxidation. Also, irradiated meat produced more volatiles than nonirradiated meat, and the chromatograms of raw and cooked irradiated meat suggested that lipid oxidation could be responsible for a small part of the off-odor in irradiated meat (Ahn and others 1997; Ahn and others 1998a, 1998b, 1999). Patterson and Stevenson (1995) found that dimethyl trisulfide is the most potent off-odor compound in irradiated chicken meat, followed by cis-3- and trans-6-nonenals, oct-1-en-3one and bis(methylthio-)methane. Hashim and others (1995) reported that irradiating uncooked chicken breast and thigh produced a characteristic “bloody and sweet” aroma that remained after the thighs were cooked, but was not detectable after the breasts were cooked. Heath and others (1990) reported that irradiating uncooked chicken breast and leg at 2 or 3 kGy produced a “hot fat,” “burned oil,” or “burned feathers” odor that remained after the thighs were cooked. Chen and others (1999) reported that irradiation before cooking did not influence lipid oxidation of cooked pork during storage. These studies also supported the concept that the changes that occur following irradiation are different from those of warmed-over flavor in oxidized meat, and that other mechanisms such as radiolysis of proteins play an important role in the production of volatiles in irradiated meat. Irradiation of amino acids produced distinct volatile compounds via the radiolytic degradation of amino acids (Jo and Ahn 2000). However, radiolytic degradations of amino acids not only occurred at side chains, but also at amino and carboxyl groups. Thus, the volatile compounds produced from amino acid monomers by irradiation cannot represent the volatiles produced from proteins. To overcome this problem, we used amino acid homopolymers in this study. The objective of this study was to determine the volatile compounds produced from each amino acid polymer by irradiation and the odor characteristics of the irradiated amino acid polymers.

The effects of added antioxidants on the oxidative quality changes of irradiated pork patties were studied. Lipid oxidation (TBARS) was not a concern, even in aerobically packaged irradiated pork patties when antioxidants were added. Irradiation produced sulfur compounds, such as dimethyl sulfide and dimethyl disulfide, responsible for irradiation off-odor. The addition of gallate + tocopherol or sesamol + tocopherol was effective in reducing the sulfur volatiles, but had no effect on the redness of irradiated raw pork patties. Aerobic packaging was highly effective in reducing sulfur volatiles and off-odor from irradiated meat during storage. Antioxidants had little effect on the sensory characteristics and consumer acceptance of irradiated pork, and consumers did not consider the red color of irradiated raw pork as a quality defect.

Irradiation not only generated many new volatiles but also destroyed some volatiles already present in nonirradiated amino acid homopolymer-in-liposome systems. The amounts of some volatiles greatly increased, but others significantly decreased after irradiation. The majority of newly generated and increased volatiles by irradiation were sulfur compounds, indicating that sulfur amino acids are the most susceptible to changes by irradiation. More than one site in amino acid side chains was labile to free radical attack, and many volatiles were produced by the secondary chemical reactions after the primary radiolytic degradation of side chains. Although nonirradiated samples also produced some sulfury notes, irradiated samples produced much a stronger and astringent sulfury odor than nonirradiated samples.

The effects of antioxidants on the flavor and color of electron-beam-irradiated turkey sausages were studied. Sausages were prepared from turkey thigh meat, NaCl (2.0%), phosphate (0.5%), water (10%), and one of five antioxidant treatments (none, vitamin E, sesamol, rosemary extract, or gallic acid at 0.02%). Sausages were stuffed and cooked in an 85 C smokehouse to an internal temperature of 74 C, then chilled and sliced to 1.5-cm thickness, and vacuum-packaged. Packaged sausages were randomly divided into three groups and irradiated at 0, 1.5 or 3.0 kGy, using an electron beam. Volatiles, color, 2-TBA-reactive substances values, and sensory characteristics were analyzed. The antioxidant effect of sesamol was the highest, followed by vitamin E and gallic acid; rosemary extract had the weakest antioxidant effect. Irradiation induced red color in sausages, but addition of gallic acid, rosemary extract, or sesamol reduced it. Gallic acid was very effective in lowering the redness of irradiated and nonirradiated sausages. The redness (a*) values of sausages with added gallic acid that were irradiated at 0, 1.5, and 3.0 kGy were 1.49,2.03, and 2.29, respectively, whereas those of control sausages under the same irradiation conditions were 2.58, 2.81, and 3.25, respectively. The reduction of redness in irradiated sausages by antioxidants was not related to CO, because antioxidants had no effect on CO production by irradiation. The amount of total volatiles was decreased significantly by antioxidants, but antioxidants had minimal effect on the off-flavor of turkey sausages induced by irradiation.

Irradiated meats produced more volatiles and higher 2-thiobarbituric acid reactive substances (TBARS) than nonirradiated regardless of animal species. Irradiation not only produced many new volatiles not found in nonirradiated meats but also increased the amounts of some volatiles found in nonirradiated meats. The amounts of volatiles in aerobically packaged irradiated meats decreased with storage while those of nonirradiated meats increased. TBARS values were the highest in beef loin, followed by turkey breast and pork loin regardless of irradiation, packaging, and storage time. TBARS of meats showed positive correlation with total volatiles, but preference scores between irradiated and nonirradiated were similar.

Turkey breast muscles were aerobically or vacuum packaged, irradiated at 0, 2.5, or 5.0 kGy using a Linear Accelerator (electron beam), and stored at 4°C. The CIE color values, reflectance scan, oxidation-reduction potential (ORP), production of gaseous compounds, and lipid oxidation of samples were determined at 0, 1, and 2 weeks of storage. Absorption spectra of sample drips were determined at 1 week of storage. Irradiation increased the a-value of both aerobically and vacuum-packaged turkey breast, but vacuum-packaged meat had stronger intensity than the aerobically packaged. The increased redness in vacuum-packaged meat was stable during the 2 weeks of storage. The production of CO in meat, which can bind to myoglobin as a sixth ligand, was proportional to irradiation dose. The ORP was decreased by irradiation, but was increased during storage. The ORP and lipid oxidation values were lower in vacuum-packaged than those in aerobically packaged turkey breast. Therefore, increased a-values in irradiated turkey breast should be caused by the decreased ORP and heme pigment-CO ligand formation. The absorption spectra of meat drip also showed that the peak wavelengths of irradiated turkey breast were similar to that of the CO-myoglobin.

This study was aimed at determining the effect of irradiation of shell eggs on the physiochemical and functional properties of liquid egg white during storage. Color and textural parameters of irradiated liquid egg white after cooking were also determined. Shell eggs were irradiated at 0, 2.5, 5, or 10 kGy using a linear accelerator. Egg white was separated from yolk and stored in at 4°C up to 14 d. Viscosity, pH, turbidity, foaming properties, color, and volatile profile of liquid egg white, and color and texture properties of cooked egg white were determined at 0, 7, and 14 d of storage. Irradiation increased the turbidity but decreased viscosity of liquid egg white. Foaming capacity and foam stability were not affected by irradiation at lower dose (2.5 kGy), but were deteriorated at higher doses (≥5.0 kGy) of irradiation. Sulfur-containing volatiles were generated by irradiation and their amounts increased as the irradiation dose increased. However, the sulfur volatiles disappeared during storage under aerobic conditions. Lightness (L* value) and yellowness (b* value) decreased, but greenness (-a* value) increased in cooked egg white in irradiation dose-dependent manners. All textural parameters (hardness, adhesiveness, cohesiveness, chewiness, and resilience) of cooked egg white increased as the irradiation dose increased, but those changes were marginal. Our results indicated that irradiation of shell egg at lower doses (up to 2.5 kGy) had little negative impact on the physiochemical and functional properties of liquid egg white, but can improve the efficiency of egg processing due to its viscosity-lowering effect. Therefore, irradiation of shell eggs at the lower doses has high potential to be used by the egg processing industry to improve the safety of liquid egg without compromising its quality.

Raw and cooked beef and pork loins were irradiated at 0 or 5 25 kGy. The radiation induced marker compounds, such as hydrocarbons, 2-alkylcyclobutanones and sulfur volatiles, were determined after 0 and 6 months of frozen storage. Two hydrocarbons [8-heptadecene (C17:1), 6,9- heptadecadiene (C17:2)] and two 2-alkylcyclobutanones [2- dodecylcyclobutanone (DCB), 2-tetradecylcyclobutanone (TCB)] were detected only in irradiated raw and cooked meats. Although pre-cooked irradiated meats produced more hydrocarbons and 2-alkylcyclobutanones than the irradiated cooked ones, the amounts of individual hydrocarbons and 2- alkylcyclobutanones, such as 8-heptadecene, 6,9- heptadecadiene, DCB, and TCB, were sufficient enough to detect whether the meat was irradiated or not. Dimethyl disulfide and dimethyl trisulfide were also detected only in irradiated meats, but dimethyl trisulfide disappeared after 6 months of frozen storage under oxygen-permeable packaging conditions. The results indicated that 8- heptadecene, 6,9-heptadecadiene, DCB, TCB and dimethyl disulfide, even though they were decreased with storage, could be used as marker compounds for the detection of irradiated beef and pork regardless of cooking under the frozen conditions for 6 months.

Hydrocarbons, gas compounds, and off-odor volatiles were determined for irradiated (0 or 5 kGy) commercial sausages with different fat contents (16% and 29%) during a 60-d storage period at 4 ◦C. Total of 4 hydrocarbons (C14:1, C15:0, C16:2, and C17:1) were detected only in irradiated sausages: the amount of C16:2 was the highest, followed by C17:1, C14:1, and C15:0. The concentrations of hydrocarbons decreased significantly (P < 0.05) with storage, but were still detectable at the end of 60-d storage. Irradiated sausages produced significantly higher amounts of CO than the nonirradiated ones. CH4 was detected only in irradiated sausages. Dimethyl disulfide was detected only in irradiated sausages and its concentration decreased significantly (P < 0.05) with storage. Fat content of sausages showed a significant effect on the production and retention of hydrocarbons, gas compounds, and sulfur volatiles in irradiated sausages during storage. Some hydrocarbons (C16:2, C17:1, C14:1, and C15:0), CH4, and dimethyl disulfide were only found in irradiated sausages indicating that these compounds can be used as potential markers for irradiated sausages.

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-C-I and V-I-C, whereas it was only slightly higher for A-I-C. 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.

An emulsion-type raw pork batter was prepared using 10% (meat weight) of backfat or commercial soybean oil enriched with vitamin E to determine the effect of irradiation on lipid oxidation and volatile production during storage. Batters (approximately 100 g) were vacuum- or aerobically packaged and irradiated at 0, 2.5 or 4.5 kGy. Irradiation increased lipid oxidation of aerobically packaged rawpork batters prepared w ith both backfat and soybean oil. Lipid oxidation of vacuum-packaged pork batters was not influenced by irradiation except for the batter prepared with backfat at day 0. Aerobically packaged batters prepared with soybean oil had lower (P50.05) TBARS than that with backfat, but vacuum-packaged ones were not different. The sum of volatile compounds with short retention time (51.80) increased by irradiation, and with storage time except for aerobic packaging at day 7. The amount of total volatile compounds had an increasing trend until day 3, but not at day 7. Irradiation increased the production of total volatile compounds in the batters prepared with soybean oil and vacuum packaged, but irradiation effect on volatile production was not consistent with other treatments. # 2001 Elsevier Science Ltd. All rights reserved.

An emulsion-type product was prepared to determine the effect of irradiation on lipid and cholesterol oxidation, color change, and volatile production in raw pork with different fat contents. Lipid oxidation increased with an increase in fat content or irradiation dose. Irradiated batters had higher cholesterol oxides than nonirradiated, and the major cholesterol oxides formed in irradiated pork batters were 7α- and 7β-hydroxycholesterol. Hunter color a- and b-values of raw pork batters were decreased by irradiation regardless of fat content. Irradiation increased the amount ofvolatiles significantly. Although lipid oxidation of high fat products (10 and 15% fat) was higher than that of low fat products (4%), high fat products did not always produce greater amount of volatiles. In summary, irradiation increased lipid and cholesterol oxidation, volatiles production and had detrimental effects on the color of raw pork batters under aerobic condition.

Irradiation dose affected production of volatiles in vacuum-and aerobic-packaged cooked pork sausage, but its effect on TBARS was minor. Storage increased production of volatiles and changed their composition only in aerobic-packaged sausage. Among volatile components, 1-heptene and 1-nonene were influenced most by irradiation dose, and aldehydes by packaging type. TBARS and volatiles of vacuum-packaged irradiated cooked sausage did not correlate well. However, TBARS had very high correlation with amount of aldehydes, total volatiles, ketones and alcohols with long retention times in aerobic-packaged pork sausage. Heptene and 1-nonene could be indicators for irradiation; and propanal, pentanal, and hexanal for oxygen-dependent changes of cooked meat.

Effects of packaging and irradiation combinations on lipid oxidation, off-flavor, and color changes of raw patties prepared from three pork muscles were studied. Patties were prepared from each of the ground L. dorsi (L. thoracis and lumborum), psoas, and R. femoris muscles of pig, packaged either in oxygen permeable polyethylene bags or impermeable nylon/polyethylene bags, irradiated with an electron beam at 0 or 4.5 kGy dose, and then stored up to two weeks at 4 °C. Lipid 8 oxidation and color of the patties were determined after 0, 3, 7, and 14 days of storage, and volatiles 24 hr after irradiation. Irradiation and high fat content accelerated the lipid oxidation in raw meat during storage. Oxygen availability during storage, however, was more important than irradiation on the lipid oxidation and color values of raw patties. Irradiated meat produced more volatiles than nonirradiated patties, and the proportion of volatiles varied by the packaging-irradiation conditions of patties. Irradiation produced many unidentified volatiles that could be responsible for the off-odor in irradiated raw meat. No single volatile components but total volatiles, however, could be used to predict lipid oxidation status of raw meat.

Raw-meat patties were prepared from three pork muscles, irradiated in different packaging environments, and stored for 0 or 3 days before cooking. Lipid oxidation by-products were formed in the raw meat during storage and the baseline lipid oxidation data of raw meat was used to measure the progression of lipid oxidation after cooking. Thiobarbituric acid-reactive substances (TBARS) and volatiles data indicated that preventing oxygen exposure after cooking was more important for cooked meat quality than packaging, irradiation, or storage conditions of raw meat. Propanal, pentanal, hexanal, 1 -pentanol, and total volatiles correlated highly (P < 0.01) with TBARS values of cooked meat. Hexanal and total volatiles represented the lipid oxidation status better than any other individual volatile components.

Breast and leg meat patties, prepared from turkeys fed diets containing 25, 200, 400 or 600 IU of dl-α-tocopheryl acetate (TA) per kg diet, were irradiated at 0 or 2.5 kGy with vacuum or loose packaging. The effects of dietary TA on storage stability and production of volatiles in irradiated raw turkey meat were determined. Dietary TA at > 200 IU/kg decreased lipid oxidation and reduced total volatiles of raw turkey patties after 7-days of storage. However, the antioxidant effects of dietary TA were more notable when the patties were loosely packaged than when vacuum-packaged. Irradiation increased lipid oxidation of raw turkey meats only when loosely packaged but had limited effects on formation of total volatiles after storage at 4°C for 7 days or longer.