Reducing lipid oxidation in irradiated ground beef patties by natural antioxidants

Abstract

Fresh ground beef patties with (1) no antioxidant, (2) 0.02% butylated hydroxyanisole/ butylated hydroxy toluene (BHA/BHT), (3) 3% dried plum puree, or (4) 0.25% rosemary extract were partially aerobic packed, irradiated at 0, 1.5, or 2.0 kGy (actual average levels 1.7 or 2.3 kGy), and stored at 4⁰C. The samples were evaluated for thiobarbituric acid (TBARS) values, sensory descriptive attributes, subjective color, and color space values after 0, 3, 7, 14, 21, and 28 days. Percent protein, fat, and moisture were determined on the raw product. For statistical validity, three batches of the experiment were conducted. Statistical analyses of the data were performed using the General Linear Model of the SAS system. Least square means of the main effects and interactions were analyzed for significance at P< 0.05. All antioxidant treatments were effective for retarding irradiation induced lipid oxidation during the storage as determined by TBARS values. BHA/BHT and rosemary extracts were the most effective antioxidants and no differences were noted between either treatment. Incorporation of 3% dried plum puree resulted in lower TBARS values than the control, but it was not as effective as BHA/BHT or rosemary extract. Irradiation at the 1.5 and 2.0 kGy targets increased TBARS values, but no differences in oxidation were noted between the irradiation dose levels. It is apparent that further comparisons should be made with dried plum puree extract that has been standardized to the same antioxidant equivalency as the rosemary extract or BHA/BHT combination. L* and b* color space values were not affected by irradiation dose, but redness (a*) decreased on day 0 and day 28 with the 2.0 kGy irradiation dose target. BHA/BHT treatments were slightly darker and less red than the control, dried plum puree, and rosemary extract. Overall, patty lightness (L*) increased with storage from day 0 to day 3 and remained unchanged thereafter. Yellowness (b* values) was variable with no clearly defined trend. Subjective ground beef color (GBC) did not differ from the control during the storage period, but the percent surface discoloration after day 0 increased from 1-19% to 20-39% and then remained unchanged. Dried plum puree slightly increased the amount of surface discoloration (AMDSC), possibly due to the color of the puree. Irradiation dose changed ground beef color (GBC) slightly causing a lighter and moderately to very light cherry-red appearance. Descriptive sensory analysis showed only very small changes in sensory attributes over the storage period. Irradiation dose changes were only marginally detectable for sensory attributes.