Fat content influences the color, lipid oxidation, and volatiles of irradiated ground beef.

Ground beef with 10%, 15%, or 20% fat were added with none, 0.05% ascorbic acid + 0.01%alpha-tocopherol, or 0.05% ascorbic acid + 0.01%alpha-tocopherol + 0.01% sesamol, and irradiated at 0 or 2.5 kGy. The meat samples were displayed under fluorescent light for 14 d at 4 degrees C. Color, lipid oxidation, volatiles, oxidation-reduction potential (ORP), and carbon monoxide (CO) production were determined during storage. Irradiation increased lipid oxidation and total volatiles of ground beef regardless of fat contents. Ascorbic acid + alpha-tocopherol + sesamol treatment was the most effective in reducing lipid oxidation during storage. The production of ethanol in nonirradiated ground beef increased dramatically after 7 d of storage due to microbial growth. Total aldehydes and hexanal increased drastically in irradiated control over the storage period, but hexanal increased the most by irradiation. L*-values was decreased by irradiation, but increased in all meat regardless of fat contents as storage period increased. Irradiation reduced the redness, but fat contents had no effect on the a*-value of ground beef. Sesamol lowered, but ascorbic acid + alpha-tocopherol maintained the redness of irradiated beef up to 2 wk of storage. The yellowness of meat was significantly decreased by irradiation. The reducing power of ascorbic acid + alpha-tocopherol lasted for 3 d, after which ORP values increased. Irradiation increased CO production regardless of fat content in ground beef. In conclusion, up to 20% fat had no effect on the quality change of irradiated ground beef if ascorbic acid + alpha-tocopherol was added.

Effect of antioxidant application methods on the color, lipid oxidation, and volatiles of irradiated ground beef.

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.

Effects of oleoresin-tocopherol combinations on lipid oxidation, off-odor, and color of irradiated raw and cooked pork patties.

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 3days during the 10-day storage was effective in controlling both lipid oxidation and irradiation off-odor, regardless of packaging sequences.