Effects of fat content, aging time, and additive application methods on the quality characteristics of irradiated ground beef
The effects of fat content, aging time and additives application methods on color, lipid oxidation and volatiles of irradiated ground beef were determined. Two different methods, mixing or spraying, of applying ascorbic acid, alpha-tocopherol, and sesamol; ground beef with 3 different aging times; and ground beef with 3 different fat contents were used in the study. Beef patties were prepared, treated with additives, placed on Styrofoam trays, wrapped with oxygen permeable plastic film, treated with electron beam irradiation at 0 or 2.5 kGy, and displayed under fluorescent light at 4°C. Color, lipid oxidation, volatiles, oxidation-reduction potential (ORP) and carbon monoxide (CO) production were determined. Irradiation accelerated lipid oxidation, reduced beef redness and produced off-odor volatiles. Beef redness (a* values) was decreased by irradiation without any influence from the application methods, fat contents and aging times. Ascorbic acid was effective in maintaining beef redness after irradiation. Lipid oxidation was accelerated by irradiation regardless of application method or fat content. Aging, however, influenced lipid oxidation where lipid oxidation increased as aging increased. Combinations of ascorbic acid, alpha-tocopherol or sesamol were effective in slowing down lipid oxidation. Adding sesamol to the combination of ascorbic acid + alpha-tocopherol made it more effective in slowing down lipid oxidation especially during late storage. Irradiation increased total volatiles production, which was not affected by fat contents. Volatiles aldehydes were tripled in amount as beef aging increased. Beef patties treated with spray application produced more hydrocarbons and alcohols than patties treated with mixing. Ascorbic acid + alpha-tocopherol was effective in reducing the produced volatiles. ORP were reduced by irradiation without being influenced by fat contents or aging times. Beef treated with mixing application had lower ORP compared with beef treated with spraying. Ascorbic acid + alpha-tocopherol was effective in reducing ORP. Irradiation increased CO production from beef patties, without any influences from application methods, aging times or fat contents.