Effect of irradiation on the quality of turkey ham during storage

Effect of electron-beam irradiation on the quality of ready-to-eat (RTE) turkey ham was studied. Turkey hams were purchased from local stores and sliced into 0.5 cm-thick pieces and vacuum packaged. The ham samples were randomly separated into three groups and irradiated at 0, 1, or 2 kGy, and stored at 4?°C for up to 14 days. Volatiles, color, TBARS values and sensory characteristics were determined to compare the effect of irradiation and storage on the quality of RTE turkey ham. Irradiation had little effects on color and TBARS values of RTE turkey hams. Sensory analysis indicated that sulfury odor increased as irradiation dose increased, and the contents of sulfur compounds in irradiated RTE turkey hams were higher (P <0.05) than those in nonirradiated samples. Irradiation increased (P <0.05) the production of acetaldehyde, which could be related to a metal-like flavor in irradiated hams. However, overall quality changes in RTE turkey hams by irradiation up to 2 kGy were minor.     

Analysis of volatile components and the sensory characteristics of irradiated raw pork

Longissimus dorsi muscle strips, approximately 20 mm long, 40 mm wide, and 5 mm thick (4 g), of pig were randomly placed in a single layer into labeled bags (four strips per bag) and packaged either aerobically or under vacuum. Samples in the bags were irradiated at 0, 5, or 10 kGy and stored at 4°C for 5 days. Lipid oxidation, the amount and identity of volatile components and sensory characteristics of raw pork strips were determined at 0 and 5 days of storage. Irradiated muscle strips produced more 2-thiobarbituric acid reactive substances (TBARS) than nonirradiated only in aerobic packaging during storage. Irradiation had no effect on the production of volatiles related to lipid oxidation, but produced a few sulfur-containing compounds not found in nonirradiated meat. This indicates that the major contributor of off-odor in irradiated meat is not lipid oxidation, but radiolytic breakdown of sulfur-containing amino acids. Many of the irradiation-dependent volatiles reduced to 50 to 25% levels during the 5-days storage under aerobic conditions. Irradiated muscle strips produced stronger irradiation odor than nonirradiated, but no irradiation dose or storage effect was found. Irradiation had no negative effect on the acceptance of meat, and approximately 70% of sensory panels characterized irradiation odor as barbecued-corn-like odor.     

Lipid oxidation, color changes and volatiles production in irradiated pork sausage with different fat content and packaging during storage

Effects of irradiation on lipid oxidation, color and volatiles production in pork sausages with different fat content and packaging were determined. Sausages (with 4.7, 10.5 and 15.8% fat content) were sliced and vacuum-packaged either in oxygen-permeable or impermeable bags, irradiated (0 or 4.5 kGy) and stored at 4°C for 7 days. Lipid oxidation, color and volatiles productions were analyzed at 0, 3 and 7 days of storage. TBARS (2-thiobarbituric acid reactive substances) values of cooked pork sausages increased with the increase of fat content regardless of storage, irradiation or packaging types. Irradiated samples had higher TBARS than nonirradiated at 0 day but the difference disappeared during storage in both packaging types. Lightness of sausages (Hunter L-value) increased with the increase of fat content and storage time but was not affected by irradiation. In aerobic packaging, irradiation reduced Hunter a-values of pork sausages at 0 day but irradiation effect on a-value disappeared during storage. In vacuum packaging, however, irradiated samples had higher Hunter a-values than nonirradiated samples. Irradiation increased 1-heptene and total volatiles, but the amount of 1-heptene was not associated well with TBARS values of pork sausages. In both irradiated and nonirradiated pork sausages, aerobic packaging produced more volatiles than vacuum packaging during storage. It was concluded that irradiation and fat content had significant effects on lipid oxidation, color and volatiles production of cooked pork sausages during storage but that oxygen availability had a stronger effect than irradiation and fat content.     

Production of Volatiles from Fatty Acids and Oils by Irradiation

ABSTRACT: 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.     

Effect of dietary conjugated linoleic acid, irradiation, and packaging conditions on the quality characteristics of raw broiler breast fillets

Skinless breast fillets were harvested from broilers fed with 0, 0.25, 0.5, or 1.0% conjugated linoleic acid (CLA) for 3 weeks. Fillets were either vacuum or aerobically packaged, then irradiated at 0 or 3.0 kGy using a Linear Accelerator. Breast fillets were analyzed for thiobarbituric acid reactive substances (TBARS), volatile profiles, and color at 0 and 7 days of storage at 4°C. Dietary CLA reduced TBARS, but had no effect on volatile profiles and color of breast fillets. Color a* value of breast fillets increased after irradiation. Irradiation also induced production of many volatiles, mainly alkanes and alkenes, which could be the breakdown products of unsaturated fatty acids and amino acids. High amount of dimethyl disulfide was detected in the volatiles of irradiated fillets. Low level of hexanal and pentanal in volatiles, together with low TBARS values, indicated that lipid oxidation of breast fillets after irradiation is not a big concern.     

Effect of muscle type, packaging, and irradiation on lipid oxidation, volatile production, and color in raw pork patties

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.     

Effects of Irradiation on Properties of Cured Ham

ABSTRACT: The quality characteristics of cured ham, treated with ionizing radiation (4.5 kGy) at different points in the curing process, were compared during a 90-d storage period. Irradiation treatments included irradiation of raw uncured ham, raw-cured ham, cured cooked ham, and a nonirradiated control. Irradiation processing increased lipid oxidation for all treatments. The raw-cured treatment resulted in significantly lower L* values compared with the control regardless of storage period. All treatments except for cured cooked ham had lower b* values over the storage period. Irradiation of cured cooked ham resulted in higher off-odor scores than all other treatments immediately following irradiation thus indicating a change in quality.     

Effect of ionizing radiation on quality characteristics of vacuum-packaged normal,pale–soft–exudative,and dark–firm–dry pork

Normal, pale–soft–exudative (PSE), and dark–firm–dry (DFD) pork Longissimus dorsi muscles were vacuum-packaged, irradiated at 0, 2.5 or 4.5 kGy, and stored at 4 °C for 10 days. The pH, color and lipid oxidation of pork were determined at 0, 5 and 10 days of storage. Volatile production from pork loins was determined at Day 0 and Day 10, and sensory characteristics at Day 7 of storage. Irradiation increased the redness of vacuum-packaged normal, PSE and DFD pork. However, the 2-thiobarbituric acid reactive substances (TBARS) values of three types of pork were not influenced by irradiation and storage time. Irradiation increased the production of sulfur (S)-containing volatile compounds, such as mercaptomethane, dimethyl sulfide, carbon disulfide, methyl thioacetate, and dimethyl disulfide, as well as total volatiles in all three types of pork. Normal pork produced higher levels of total and S-containing volatile compounds than the PSE and DFD pork did. The volatiles produced by irradiation were retained in the vacuum packaging bag during storage. Although the odor preference for the three meat types of pork was not different, the panelists could distinguish irradiated meat from the non-irradiated. Industrial relevance: Several US meat companies have already started test-marketing irradiated meat products. Irradiation and the subsequent storage of pork improved the color of PSE and DFD pork, and showed generally similar effects on the production of volatiles, except that there appeared to be a lower level of S-volatiles in the PSE than in the other two samples. This indicated that irradiation can increase the utilization of low-quality pork (PSE and DFD). DFD pork, in particular, which has shorter shelf-life than the others, could benefit the most from irradiation because the shelf-life of DFD meat can be extended significantly by both the methods of vacuum packaging and irradiation.     

Lipid Oxidation, Volatiles and Color Changes of Irradiated Pork Patties Affected by Antioxidants

Changes were measured in TBARS, color, and volatiles of irradiated (4.5 kGy) pork patties with antioxidants (sesamol, quercetin, rutin, BHT, and rosemary oleoresin) during 7 days storage at 4°C. Irradiation accelerated lipid oxidation of raw pork during storage. However, irradiation before cooking did not influence lipid oxidation of cooked pork during storage. Sesamol, quercetin, and BHT were effective in both irradiated raw and cooked pork during 7-days storage. Rosemary oleoresin and rutin were effective only in irradiated raw pork for 3 days. Hexanal, propanal and higher boiling components were well correlated (P < 0.01) with TBARS in cooked pork. Generation of volatiles was reduced by sesamol and quercetin, but the effects of antioxidants on color changes of raw pork patties were minor and inconsistent.     

LIPID AND CHOLESTEROL OXIDATION,COLOR CHANGES,AND VOLATILE PRODUCTION IN IRRADIATED RAW PORK BATTERS WITH DIFFERENT FAT CONTENT1

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.     

辐照对猪肉火腿肠风味与品质的影响

分别以1、3、5、7、9 kGy剂量辐照处理火腿肠,然后对其辐照异味强度、脂质氧化、挥发性风味化合物、色差等指标进行检测,分析辐照对火腿肠风味及颜色品质的影响。结果发现,辐照处理可以显著促进火腿肠中脂质的氧化(P0.05),使得红度值(a~*)相比对照组显著降低(P0.05),但是对亮度值(L~*)和黄度值(b~*)影响不显著(P0.05)。随着辐照剂量加大,火腿肠的辐照异味明显增强,1~5 kGy范围内辐照异味不明显,当辐照剂量增加到7 k Gy时,火腿肠产生明显的令消费者不能接受的辐照异味。挥发性含硫化合物、2-丁烯、戊烷、1-戊烯、辛烷、己烷以及醛类化合物含量与对照组相比显著增多(P0.05),且与辐照剂量呈正相关。二硫化碳、二甲基二硫醚、2-甲基丙醛、3-甲基丁醛、己醛、丁烯和二甲苯是火腿肠辐照后产生的最主要挥发性化合物。结果表明,火腿肠经辐照处理后风味和色泽会发生劣变,特别是5 kGy以上的辐照剂量,并且这些品质变化与火腿肠中脂质的氧化密切相关。     

Addition of Antioxidant to Improve Quality and Sensory Characteristics of Irradiated Pork Patties

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.     

Volatile profiles, lipid oxidation and sensory characteristics of irradiated meat from different animal species

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.     

Formation of Trans Fatty Acids in Ground Beef and Frankfurters due to Irradiation

ABSTRACT:  This study was conducted to investigate possible formation of trans fatty acids due to irradiation of ground beef and frankfurters. Ground beef and frankfurter samples were irradiated at doses of 0, 1, and 5 kGy at 4 °C, and stored at 4 °C for 7 d (ground beef) or 3 mo (frankfurters). After irradiation and storage of the samples, trans fatty acids along with other fatty acids were analyzed using a modification of AOAC method 996.01. The results showed that 1 kGy irradiation did not induce any change in trans fatty acid content. However, 5 kGy irradiation caused a small but statistically significant ( P < 0.01) increase in the dominant trans fatty acid, C18:1 trans , which increased from 3.99% (of total fatty acid) for the nonirradiated ground beef to 4.05% for the 5 kGy sample, and from 1.21% for the nonirradiated frankfurter to 1.28% for the 5 kGy sample. Irradiation had no apparent effect on C16:1 and C18:2 trans fatty acids. In addition, irradiation slightly decreased the relative amount of poly-unsaturated fatty acid of ground beef and frankfurters, particularly after storage. Compared to variations in trans fatty acid content and fatty acid composition occurring naturally in meat and meat products, the changes due to irradiation were negligible.     

Irradiation-induced Cured Ham Color Fading and Regeneration

ABSTRACT: Color stability of cured ham as a result of irradiation, packaging atmosphere, and storage time was evaluated. Sliced cured ham was packaged in aerobic or vacuum atmospheres, irradiated at 0, 1.2, 2.3, and 4.5 kGy and stored for 0 and 7 d. The ham treatments were evaluated for cured color, oxidation-reduction potential, and residual nitrite content. Irradiation decreased cured color as irradiation dose increased from 0 to 4.5 kGy as evidenced by lower a*/b* ratios and cured pigment analysis regardless of packaging atmosphere. Residual nitrite levels were also lower for the 4.5-kGy treatment compared with nonirradiated control following irradiation. Cured color was regenerated over time and resulted in higher a*/b* 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-packaged treatment that was irradiated at 4.5 kGy compared with the 0-kGy treatment.     

Lipid Oxidation, Color, Volatiles, and Sensory Characteristics of Aerobically Packaged and Irradiated Pork with Different Ultimate pH

ABSTRACT: 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.     

Influence of dietary conjugated linoleic acid on volatile profiles, color and lipid oxidation of irradiated raw chicken meat

Forty-eight, 27-week-old White Leghorn hens were fed a diet containing 0, 1.25, 2.5 or 5.0% conjugated linoleic acid (CLA) for 12 weeks. At the end of the 12-week feeding trial, hens were slaughtered, and boneless, skinless breast and leg meats were separated from carcasses. Meats were ground through 9 and 3-mm plates, and patties were prepared. Patties prepared from each dietary treatment were divided into two groups and either vacuum- or aerobic-packaged. Patties were irradiated at 0 or 3.0 kGy using a linear accelerator and stored at 4°C. Samples were analyzed for thiobarbituric acid reactive substances, volatile profiles, color and odor characteristics at 0 and 7 days of storage. Dietary CLA reduced the degree of lipid oxidation in raw chicken meat during storage. The content of hexanal and pentanal in raw chicken meat significantly decreased as dietary CLA level increased. Irradiation accelerated lipid oxidation in meat with aerobic packaging, but irradiation effect was not as significant as that of the packaging. Dietary CLA treatment improved the color stability of chicken patties. Color a*-value of irradiated raw chicken meat was higher than that of the nonirradiated meat. Dietary CLA decreased the content of polyunsaturated fatty acid and increased CLA in chicken muscles, which improved lipid and color stability and reduced volatile production in irradiated and nonirradiated raw chicken meat during storage.     

Quality characteristics of pork patties irradiated and stored in different packaging and storage conditions

Patties were made from pork loin, individually vacuum- or aerobic-packaged and stored either at 4 or -40°C. Refrigerated patties were irradiated at 0, 1.5, 3.0 or 4.5 kGy absorbed dose, and frozen ones were irradiated at 0, 2.5, 5.0, or 7.5 kGy. Samples were analyzed for lipid oxidation, volatile production and odor characteristics. Refrigerated samples were analyzed at 0, 1 and 2 weeks, and frozen ones after 0, 1.5 and 3 months of storage. With vacuum packaging, the lipid oxidation (TBARS) of both refrigerated and frozen patties was not influenced by irradiation and storage time except for the patties irradiated and refrigerated at 7.5 kGy. With refrigerated storage, panelists could detect irradiation odor at day 0, but not after 1 week at 4°C. With frozen storage, however, irradiation odor was detected even after 3 months of storage. With aerobic packaging, the TBARS of refrigerated pork patties increased with storage time. The TBARS of pork patties increased as irradiation dose increased at day 0, but the effect disappeared after 1 week at 4°C. Nonirradiated patties were preferred to the irradiated ones at day 0 because of the significant irradiation odor in the irradiated ones, but the off-odor disappeared after 1 week at 4°C. With frozen storage, patties irradiated at 7.5 kGy had higher TBARS than those irradiated at lower doses. Nonirradiated patties had higher preference scores than the irradiated ones for 1.5 months in frozen storage. Sulfur-containing compounds were responsible for most of the irradiation off-odor, but these volatilized quickly during storage under aerobic conditions. Overall, vacuum packaging was better than aerobic packaging for irradiation and subsequent storage of meat because it minimized oxidative changes in patties and produced minimal amounts of volatile compounds that might be responsible for irradiation off-odor during storage.     

Influence of rosemary-tocopherol/packaging combination on meat quality and the survival of pathogens in restructured irradiated pork loins

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 D(10) values for L. monocytogenes and S. typhimurium were 0.58 and 0.55kGy, 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.