An early-postmortem metabolic comparison among three extreme acute heat stress temperature settings in chicken breast muscle.

Normally, preslaughter acute heat stress could accelerate postmortem glycolysis and impair chicken breast (pectoralis major muscle) quality. However, previous studies indicated that it might be different when the acute heat stress temperature rises to an extreme range (above 35 °C). Therefore, this study's objectives were to compare the pH decline, glycolytic enzyme activity, and AMP-activated protein kinase (AMPK) phosphorylation at early postmortem among three extreme acute heat stress temperature settings: a control group (36 °C) and two experimental groups (38 °C and 40 °C). Although the temperature did not affect glycogen phosphorylase a and pyruvate kinase activity, there was a decrease in pH decline rate, phosphofructokinase-1 activity, and phospho-AMPK-α[Thr172] within 4 h postmortem when temperature increased from 36 to 40 °C. Temperature also affected hexokinase activity, with the 36 °C-group having the highest activity. The results of the current study, for the first time, indicated that postmortem metabolic rate in chicken breast muscle could be changed by acute heat stress temperature setting at extreme range.

E-sensing, calibrated PSL, and improved ESR techniques discriminate irradiated fresh grapefruits and lemons.

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 (PSL1) 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 (PSL2/PSL1). 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 < 0.05 kGy).

Effective Preparation Method of Phosphopeptides from Phosvitin and the Analysis of Peptide Profiles Using Tandem Mass Spectrometry.

The effect of high-temperature and mild-pressure (HTMP) pretreatment on the enzymatic hydrolysis of phosvitin and the structural characteristics of the phosphopeptides produced were analyzed using tandem mass spectrometry. The HTMP pretreatment hydrolyzed phosvitin at random sites and helped the subsequent enzyme hydrolysis of the peptides produced. With the HTMP pretreatment alone, 154 peptides were produced, while the use of trypsin, Protex 6L, and Multifect 14L in combination with the pretreatment produced 252, 280, and 164 peptides, respectively. The use of two enzyme combinations (trypsin + Protex 6L and trypsin + Multifect 14L) helped the hydrolysis further. The number of phosphopeptides produced increased when the modifications within the same amino acid sequences were considered. This study indicated that HTMP pretreatment was a breakthrough method to improve the enzymatic hydrolysis of phosvitin that enabled an easy production of phosvitin phosphopeptides for their subsequent functional characterizations.

Development of non-dairy creamer analogs/mimics for an alternative of infant formula using egg white, yolk, and soy proteins.

OBJECTIVE: A study was conducted to develop non-dairy creamer analogs/mimics using egg white, egg yolk, soy protein and their combinations, and their nutrient content, shelf-life and flavor acceptability were compared. METHODS: Spray dried egg white, egg yolk, and soy protein isolate were purchased from manufacturers and used for the formulae. RESULTS: The protein contents of the non-dairy creamer analogs/mimics were about 8.5% as calculated. The amounts of oleic and linoleic acid content increased as the amount of yolk increased in the formula, but the increases of polyunsaturated fatty acids were <0.5% of total fat. Addition of egg yolk to the formula increased choline and lutein content in the products, but the amounts were <0.4 mg/g for choline and 4 µg/g for lutein. The lutein in the products continued to decrease over the storage time, and only about 15% to 20% of the 0-month amounts were left after 3 months of storage. Although the thiobarbituric acid reactive substances values of the spray-dried non-dairy creamer analogs/mimics increased as storage time increased, the values were still low. Yellowness, darkness, and egg flavor/odor of the non-dairy creamer analogs/mimics increased as the amount of egg yolk in the formula increased. The overall acceptability of the non-dairy creamer analogs/mimics was closely related to the intensity of egg flavor/odor, but storage improved their overall acceptance because most of the off-odor volatiles disappeared during the storage. Water temperature was the most important parameter in dissolving spray-dried non-dairy creamer analogs/mimics, and 55°C to 75°C was the optimal water temperature conditions to dissolve them. CONCLUSION: Higher amounts of yolk and soy protein combinations in place of egg white reduced the cost of the products significantly and those products contained better and balanced nutrients than the commercial coffee creamers. However, off-flavor and solubility were two important issues in the products.

How Can the Value and Use of Egg Yolk Be Increased?

The major driving force for the egg consumption in the United States over the past few decades was processed egg. However, the consumption of egg through the processed egg reached the plateau in recent years because of the imbalance in the demands between the egg white and yolk products. The consumer demands for egg white products are very high while those for the egg yolk, the co-product of dried egg white, are low because of the negative perceptions on egg yolk. Two key approaches that can be used to increase the value and use of egg yolk are: (1) developing new commodity products by fractionating egg yolk and apply them in various food processing, and (2) separating functional proteins and lipids from yolk and use them as is or further develop functional peptides and functional lipids and use them as pharmaceutical, nutraceutical, and cosmeceutical agents. These approaches can diversify the use of egg yolk, which eventually will help increase the consumption of egg. This review (1) discusses the current use of egg yolk products and the development of new functional commodity products from egg yolk, (2) review the important functional components in egg yolk and overview the current separation methods and their applications, (3) discuss the production of functional peptides and lipids using the separated egg proteins and lipids, and (4) suggest the future directions for the best use of egg yolk components. Development of scale-up production methods, which is vital for the practical applications, is discussed when appropriate.

How can heat stress affect chicken meat quality? - a review.

Heat stress is one of the most important environmental stressors for the poultry industry in the world. Reduced growth rate, low feed efficiency, impaired immunological responses, changes in intestinal microflora, and deterioration of meat quality are the consequences of acute or chronic heat stress. In terms of meat quality, 3 primary mechanisms have been suggested to explain this phenomenon: 1) rapid drop in pH during and after slaughter due to the glycogen conversion to increase in lactic acid accumulation especially when the muscle temperature is high, a combination of high temperature and low pH that facilitates the denaturation of sarcoplasmic proteins resulting in lower water-holding capacity of muscle; 2) acceleration of panting to dissipate body heat, which increases CO2 exhalation and pH drop in blood, initiates metabolic acidosis in skeletal muscle. Increase in panting is also associated with a high release of corticosteroid hormones; 3) the reactive oxygen species produced by heat stress increases the oxidative stress in the birds, which can damage the structure and functions of the enzymes that regulate sarcoplasmic calcium levels in muscles. Overall, these changes in the muscle cells accentuate energy expenditure due to constant muscle contractions. This review discusses the scientific evidence about how heat stress affects the quality of chicken meat through the acid/base status, oxidative reactions, and changes in hormonal secretions.

Effect of irradiation on the parameters that influence quality characteristics of uncured and cured cooked turkey meat products.

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.

Effect of Packaging and Antioxidant Combinations on Physicochemical Properties of Irradiated Restructured Chicken Rolls.

Effects of double packaging (combinational use of aerobic and vacuum conditions) and antioxidants on physicochemical properties in irradiated restructured chicken rolls were determined. Chicken breast treated with antioxidants (none, sesamol+a-tocopherol) was used to process restructured chicken breast rolls. The sliced rolls were vacuum, aerobic, or double packaged (vacuum for 7 d then aerobic for 3 d) and electron beam irradiated at 2.5 kGy. Color, 2-thiobarbituric acid reactive substances (TBARS), oxidation reduction potentials (ORP), and volatile profiles of the samples were determined at 0 and 10 d. Irradiation made restructured chicken rolls redder (p<0.05), and the increased redness was more distinct in irradiated vacuum-packaged than irradiated aerobic or double packaged meats. TBARS values of antioxidant-treated double packaged rolls were lower than even nonirradiated vacuum-packaged meat, and those were distinct at 10 d (p<0.05). ORP and lipid oxidation values were lower in irradiated vacuum and double packaged samples than those in irradiated aerobic packaged ones at 0 d (p<0.05). Irradiation of restructured chicken rolls increased the amount of total volatiles. Considerable amounts of off-odor volatiles were reduced or not detected by double packaging and antioxidant treatment at 10 d. Therefore, the combined use of antioxidants and double packaging would be useful to reduce redness and control the oxidative quality changes of irradiated restructured chicken rolls.

Characterisation of phosvitin phosphopeptides using MALDI-TOF mass spectrometry.

Putative phosphopeptides produced from enzyme hydrolysis of phosvitin were identified and characterised using MALDI-TOF/MS. Phosvitin was heat-pretreated and then hydrolysed using pepsin, thermolysin, and trypsin at their optimal pH and temperature conditions with or without partial dephosphorylation. Pepsin and thermolysin were not effective in producing phosphopeptides, but trypsin hydrolysis produced many peptides from phosvitin: 12 peptides, 10 of which were phosphopeptides, were identified from the trypsin hydrolysate. Twelve peptides were also identified from the trypsin hydrolysate of partially dephosphorylated phosvitin, but the phosphate groups remaining with the peptides were much smaller than those from the trypsin hydrolysate of intact phosvitin. This suggested that the phosphopeptides produced from the partially dephosphorylated phosvitin lost most of their phosphate groups during the dephosphorylation step. Therefore, partial dephosphorylation of phosvitin before trypsin hydrolysis may not be always recommendable in producing functional phosphopeptides if the phosphate groups play important roles for their functionalities.

Induction of apoptosis by isoegomaketone from Perilla frutescens L. in B16 melanoma cells is mediated through ROS generation and mitochondrial-dependent, -independent pathway.

We have demonstrated for the first time the mechanism underlying ROS-mediated mitochondria-dependent apoptotic cell death triggered by isoegomaketone (IK) treatment in melanoma cells. We showed that IK induced apoptotic cell death and tumor growth inhibition using tissue culture and in vivo models of B16 melanoma. Furthermore, we observed that IK effectively induced apoptotic cell death, including sub-G1 contents up-regulation, nuclei condensation, DNA fragmentation, and caspase activation in B16 melanoma cells. Pretreatment with caspase inhibitor increased the survival rate of IK-treated B16 cells, implying that caspases play a role in IK-induced apoptosis. Furthermore, IK treatment generated ROS in melanoma cells. We also determined whether or not IK-induced cell death is due to ROS production in B16 cells. N-acetyl cysteine (NAC) inhibitedIK-induced Bcl-2 family-mediated apoptosis. This result indicates that IK-induced apoptosis involves ROS generation as well as up-regulation of Bax and Bcl-2 expression, leading to release of cytochrome c and AIF. Our data suggest that IK inhibits growth and induces apoptosis in melanoma cells via activation of ROS-mediated caspase-dependent and -independent pathways.

Breast meat quality of broiler chickens can be affected by managing the level of nitric oxide.

The objective of this study was to investigate the effects of nitric oxide (NO) on the quality of broiler chicken meat during postmortem storage. Eighteen broiler chickens were slaughtered and breast meat was randomly assigned to 1 of 3 treatments including the control group, nitric oxide synthase (NOS) inhibitor group, and NO enhancer group. The breast samples were incubated with water, NO enhancer, and NO inhibitor for 1 d and then stored at 4°C under atmospheric conditions for 4 and 7 d. Left side of breast meat was used to determine protein oxidation, lipid oxidation, water-holding capacity, and pH, whereas the right side was used for the measurement of color and drip loss. Breast meat from NO enhancer group showed the lowest water-holding capacity during refrigerated storage, whereas drip losses were not significantly (P > 0.05) different among 3 treatments. Lipid oxidation showed a significant difference (P < 0.05) only at 7 d in which NOS inhibitor group showed the highest, whereas the NO enhancer group showed the lowest levels of lipid oxidation. Carbonyl content in NO enhancer group was significantly higher than the control and NOS inhibitor treatment at 1 and 4 d of refrigerated storage. Lightness of breast meat in the NOS inhibitor group was greater, whereas redness was lower than the control and NO enhancer group at 4 and 7 d of refrigerated storage. The ultimate pH of 3 treatments was not significantly (P > 0.05) different from one another. These data indicate that NO could play a significant role in modulating the quality of fresh broiler breast meat during refrigerated storage.

Protein oxidation: basic principles and implications for meat quality.

The involvement of oxidized proteins to the development of biological diseases has been studied for a few decades, but the effects and the mechanisms of protein oxidation in food systems are largely unknown. Protein oxidation is defined as the covalent modification of a protein induced either by the direct reactions with reactive oxygen species (ROS) or indirect reactions with secondary by-products of oxidative stress. ROS can cause oxidation in both amino acid side chains and protein backbones, resulting in protein fragmentation or protein-protein cross-linkages. Although all amino acids can be modified by ROS, cysteine, and methionine that are the most susceptible to oxidative changes due to high reaction susceptibility of the sulfur group in those amino acids. Oxidative modifications of proteins can change their physical and chemical properties, including conformation, structure, solubility, susceptibility to proteolysis, and enzyme activities. These modifications can be involved in the regulation of fresh meat quality and influence the processing properties of meat products. Oxidative stress occurs when the formation of oxidants exceeds the ability of antioxidant systems to remove the ROS in organisms. Increased levels of protein oxidation have been associated with various biological consequences, including diseases and aging, in humans and other animal species. The basic principles and products of protein oxidation and the implications of protein oxidation in food systems, especially in meat, are discussed in this review.

Irradiation and additive combinations on the pathogen reduction and quality of poultry meat.

Reduction of foodborne illnesses and deaths by improving the safety of poultry products is one of the priority areas in the United States, and developing and implementing effective food processing technologies can be very effective to accomplish that goal. Irradiation is an effective processing technology for eliminating pathogens in poultry meat. Addition of antimicrobial agents during processing can be another approach to control pathogens in poultry products. However, the adoption of irradiation technology by the meat industry is limited because of quality and health concerns about irradiated meat products. Irradiation produces a characteristic aroma as well as alters meat flavor and color that significantly affect consumer acceptance. The generation of a pink color in cooked poultry and off-odor in poultry by irradiation is a critical issue because consumers associate the presence of a pink color in cooked poultry breast meat as contaminated or undercooked, and off-odor in raw meat and off-flavor in cooked meat with undesirable chemical reactions. As a result, the meat industry has difficulties in using irradiation to achieve its food safety benefits. Antimicrobials such as sodium lactate, sodium diacetate, and potassium benzoate are extensively used to extend the shelf-life and ensure the safety of meat products. However, the use of these antimicrobial agents alone cannot guarantee the safety of poultry products. It is known that some of the herbs, spices, and antimicrobials commonly used in meat processing can have synergistic effects with irradiation in controlling pathogens in meat. Also, the addition of spices or herbs in irradiated meat improves the quality of irradiated poultry by reducing lipid oxidation and production of off-odor volatiles or masking off-flavor. Therefore, combinations of irradiation with these additives can accomplish better pathogen reduction in meat products than using them alone even at lower levels of antimicrobials/herbs and irradiation doses. Effects of irradiation and additive combinations on the pathogen reduction and quality of poultry meat will be discussed in detail.

Effects of increasing concentrations of corn distillers dried grains with solubles on chemical composition and nutrient content of egg.

The objective of this study was to determine the effects of feeding high concentrations of corn distillers dried grains with solubles (DDGS) on chemical composition and selected nutrient content of egg yolk. Four isocaloric diets were formulated to contain 0, 17, 35, or 50% corn DDGS. A total of two hundred forty 54-wk-old Single-Comb White Leghorn laying hens were randomly allotted to 2 birds per cage with 3 consecutive cages representing an experimental unit (EU). Each EU was randomly assigned to 1 of 4 dietary treatments according to a completely randomized design. Hens were fed for a 24-wk experimental period after transition feeding to gradually increase corn DDGS inclusion over a 4-wk period. Two sets of experimental diets were formulated to meet or exceed the NRC nutrient recommendations for laying hens. Each diet formula was fed for 12 wk. Chemical composition and nutritional components in egg yolk were measured every 2 wk. The results showed that egg yolk from hens fed a DDGS-containing diet tended to have higher fat content and lower protein content. Total polyunsaturated fatty acids were significantly increased by the DDGS diet. The contents of choline and cholesterol were initially higher in the 50% DDGS treatment group, but were not different in the later period, especially during the last 4 wk. Lutein content increased linearly as DDGS level increased. The results indicated that feeding a high level of DDGS can increase the content of lutein and polyunsaturated fatty acids in egg yolk, but may not affect the content of cholesterol and choline.

Effects of increasing concentrations of corn distillers dried grains with solubles on the egg production and internal quality of eggs.

A study was conducted to determine the effect of feeding high concentrations of corn distillers dried grains with solubles (DDGS) on egg production and the internal quality of eggs from laying hens. Four diets were formulated to contain 0, 17, 35, or 50% corn DDGS. A total of two hundred forty 54-wk-old Single-Comb White Leghorn laying hens were randomly allotted to 2 birds per cage with 3 consecutive cages representing an experimental unit (EU). Each EU was assigned to 1 of 4 dietary treatments according to a completely randomized design. Hens were fed for a 24-wk experimental period after transition feeding to gradually increase corn DDGS inclusion over a 4-wk period. Two sets of experimental diets were formulated, and each diet was fed for 12 wk. Egg production, feed consumption, egg component, yolk color, Haugh unit during storage times, and shell breaking strength were measured. Egg production, egg weight, egg mass, feed intake, and feed efficiency were adversely affected by the highest level of DDGS in the diet (50%) during the first 12-wk period. Once diets were reformulated to include an increased concentration of both lysine and methionine, differences among the dietary treatments were reduced, as the performance of the 50% DDGS diets was greatly improved. Over the last 6 wk of study, no differences in egg production, egg weight, and feed intake among DDGS treatments were found. The DDGS diets positively affected the internal quality of eggs during storage. Improved yolk color and Haugh unit were observed as the dietary DDGS levels increased, but the increase for Haugh unit was significant only when the DDGS level was 50%. Shell weight percentage was increased in the 50% DDGS diet, but no differences in yolk and albumen percentage were observed. It was concluded that up to 50% of DDGS could be included in the layer's diet without affecting egg weight, feed intake, egg mass, feed efficiency, and egg production as long as digestible amino acids were sufficient in DDGS-added diets.

Potential chemical markers for the identification of irradiated sausages.

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. CH(4) 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), CH(4) , and dimethyl disulfide were only found in irradiated sausages indicating that these compounds can be used as potential markers for irradiated sausages.

Effects of high-pressure processing and enzymatic dephosphorylation on phosvitin properties.

BACKGROUND: Egg phosvitin could be a good source of functional peptides. Enzymatic dephosphorylation and high-pressure processing combined with thermal treatment applied before proteolysis could produce phosvitin hydrolysates with different properties compared to its native form. RESULTS: Phosvitin structure was maintained overall during high-pressure treatment of 600 MPa applied at an initial temperature of 65 °C regardless of the pH and duration of treatment, confirming the high structural stability of this phosphoprotein. Treatment of phosvitin with phosphatase increased the degree of dephosphorylation from 24% to 63%, after 2 and 18 h, respectively. Moderate dephosphorylation of phosvitin prior to proteolytic digestion improved its hydrolysis, allowing formation of peptides with a molecular weight lower than 17,000 kDa as determined by size exclusion chromatography. Angiotensin-converting enzyme (ACE) inhibition and antioxidant activity of dephosphorylated and protease-treated phosvitin was increased by 52% and 39%, respectively, as compared to protease-digested native phosvitin. CONCLUSION: Enzymatic dephosphorylation before proteolysis mimicking in vivo gut conditions improved ACE inhibition and antioxidant activity of phosvitin hydrolysates.

Effect of cooking on radiation-induced chemical markers in beef and pork during storage.

UNLABELLED: Raw and cooked beef and pork loins were irradiated at 0 or 5 kGy. The radiation-induced marker compounds, such as hydrocarbons, 2-alkylcyclobutanones (2-ACBs), and sulfur volatiles, were determined after 0 and 6 mo of frozen storage. Two hydrocarbons (8-heptadecene [C(17:1)] and 6,9-heptadecadiene [C(17:2)]) and two 2-ACBs (2-dodecylcyclobutanone [2-DCB] and 2-tetradecylcyclobutanone [2-TCB]) were detected only in irradiated raw and cooked meats. Although precooked irradiated meats produced more hydrocarbons and 2-ACBs than the irradiated cooked ones, the amounts of individual hydrocarbons and 2-ACBs, such as 8-heptadecene, 6,9-heptadecadiene, 2-DCB, and 2-TCB, were sufficient enough to detect whether the meat was irradiated or not. Dimethyl disulfide and dimethyl trisulfide were also determined only in irradiated meats but dimethyl trisulfide disappeared after 6 mo of frozen storage under oxygen-permeable packaging conditions. The results indicated that 8-heptadecene, 6,9-heptadecadiene, 2-DCB, 2-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 mo. PRACTICAL APPLICATION: Radiation-induced chemical changes such as specific hydrocarbons, 2-ACBs, and sulfur volatiles may be used as potential identification markers by regulatory authorities to confirm irradiation history of frozen stored raw or cooked beef and pork.

Egg yolk phosvitin and functional phosphopeptides--review.

Phosphopeptides are among the most interesting biomolecules with characteristic molecular structure and functions. They usually contain clusters of phosphoserines, which can effectively bind calcium and iron, and inhibit formation of insoluble calcium phosphates or iron complexes. Therefore, phosphopeptides can increase calcium or iron bioavailability and prevent lipid oxidation in foods. Milk protein casein has been currently used by industry to produce phosphopeptides. Egg yolk phosvitin is considered as the most phosphorylated protein found in the nature. Phosvitin from egg yolk can be much better source for producing phosphopeptides with varying sizes and functions than casein because it contains much greater number of phosphates in the molecule than casein. However, still phosvitin has not been subjected to considerable attention with regard to bioactive peptides production.

Effect of garlic, onion, and their combination on the quality and sensory characteristics of irradiated raw ground beef.

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 <0.01% garlic would be needed to mask or prevent irradiation aroma in irradiated raw ground beef.