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H. A. SEPE, C. L. Miano, Y. L. Xiong, and A. L. Alderton. Dept. of Animal Sciences, Univ. of Kentucky, Food Science Program, 214 W.P. Garrigus Bldg., Lexington, KY 40546-0215 Oxidation often leads to a decline of quality during storage of ground beef. Added antioxidants, such as vitamin E, can enhance meat quality and effectively stabilize red, oxymyoglobin color by delaying oxidation. The objective of this study was to determine the effects of vitamin E on the heat stability of myoglobin (Mb) in ground beef. Ground chuck containing added vitamin E (α-tocopherol acetate; 0.06% w/w) and/or NaCl (1.5% w/w) was analyzed for fat, moisture and Mb content following 6 days of refrigerated storage (4° C). Mb was extracted from samples through precipitation with ammonium sulfate and purified using column chromatography. Extracted Mb was heated at approximately 0.8° C/min and 1.4° C/min to an endpoint temperature of 80° C. Absorbance of the Mb solution before and after heating was determined at 525nm and 540nm and the percentage of denaturation calculated. The thermal denaturation of Mb began at 40° C for samples heated at 0.8° C/min. The point of denaturation during heating at 1.4° C/min was not as clearly defined. When heated at 0.8° C/min, samples containing vitamin E had a significantly lower percentage of denatured Mb (P<0.05), losing less than 5% of total Mb at 80° C. Treatments containing no vitamin E (with or without salt) lost approximately 25% of total Mb. When heated at a rate of 1.4° C/min, all treatments resulted in less than 10% loss of total Mb at 80° C. Treatments containing NaCl were most susceptible to Mb denaturation, followed by treatments containing vitamin E, and finally, the control. In general, slower heating rates increased Mb susceptibility to denaturation when not combined with vitamin E. The addition of vitamin E to ground beef may delay oxidation and effectively protect Mb from denaturation, thereby slowing the decline of quality during storage and increasing product shelf life.
Session 68, Muscle Foods: Biochemistry, color and non-meat ingredients
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |