Reduction of irradiation off-odor and lipid oxidation in ground beef by α-tocopherol addition and the use of a charcoal pack

A combination of a charcoal pack during irradiation and alpha-tocopherol addition into ground beef was applied to eliminate an irradiation characteristic off-odor and to retard the lipid oxidation caused by the irradiation process. Ground beef was mixed with 200 ppm alpha-tocopherol and gamma irradiated with 0, 5. and 10 kGy with or without a charcoal pack present during the irradiation treatment. The pH of the control group was lower than that of alpha-tocopherol and charcoal pack treatment initially but increased rapidly and showed higher pH at day 7. Addition of alpha-tocopherol with or without charcoal pack addition showed lower 2-thiobarbituric acid reactive substances values in irradiated ground beef at days 3 and 7 compared to those without addition. The color of ground beef was not significantly affected by the treatment. However, odor preference result showed that 10 kGy-irradiated ground beef with a combination of charcoal pack and alpha-tocopherol addition had higher scores than the control group regardless of irradiation. Solid-phase microextraction (SPME) gas chromatograph/mass spectrometry (GC/MS) analysis identified various volatile compounds that were created by irradiation of ground beef. These compounds were reduced or eliminated when a charcoal pack was used during the irradiation process. The results of the present study imply that combination of packaging with a charcoal pack during the irradiation process and addition of alpha-tocopherol into ground beef is a good method to effectively eliminate an irradiation off-odor and retard the lipid oxidation development in ground beef caused by irradiation. (C) 2008 Elsevier Ltd. All rights reserved.