August 26/Food & Farm Week -- According to a study from the U.S., "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 seven days 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-dagger - 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(dagger) -value of ground beef. Sesamol lowered, but ascorbic acid+ alpha-tocopherol maintained the redness of irradiated beef up to 2wk of storage. The yellowness of meat was significantly decreased by irradiation. The reducing power of ascorbic acid + a-tocopherol lasted for 3 d, after which ORP values increased. Irradiation increased CO production regardless of fat content in ground beef," wrote H.A. Ismail and colleagues, Iowa State University.
The researchers concluded, "Up to 20% fat had no effect on the quality change of irradiated ground beef if ascorbic acid + a-tocopherol was added."
Ismail and colleagues published the results of their research in the Journal of Food Science ("Fat Content Influences the Color, Lipid Oxidation, and Volatiles of Irradiated Ground Beef." Journal of Food Science, 2009;74(6):C432-C440).
For additional information, contact D.U. Ahn, Iowa State University, Dept. of Animal Science, Ames, IA 50011.
From the August 31, 2009, Prepared Foods E-dition