Date of Award

1999

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

School of Nutrition and Food Sciences

First Advisor

J. Samuel Godber

Abstract

The effects of semi-purified extracts of rice bran were studied in restructured beef roasts to increase nutritional value and oxidative stability. Crude rice bran oil at 0, 1, and 2% (w/w) was added to restructured beef roasts that were stored at 4°C and analyzed at 0, 7, and 14 d. Saturated fatty acid to unsaturated fatty acid (SFA/UFA) ratio decreased, vitamin E vitamers increased (p < 0.05), and cholesterol decreased in the beef roasts with rice bran oil. Thiobarbituric acid reactive substances (TBARs) numbers were lower (p < 0.05) in the beef roasts with rice bran oil after 7 days of storage and the cholesterol oxidation product, 7-ketocholesterol, decreased in a similar manner. The addition of 2% rice bran oil (RBO) was effective in increasing nutritional value and reducing the level of oxidative degradation. Beef roasts containing either rice fiber (RF) or RF/RBO had higher oxidative stability (p < 0.05) during storage (0, 4, and 8 d) compared to control roasts, with no additive. TBARs value and 7-ketocholesterol of beef roasts with RF and RF/RBO were lower (p < 0.05) than those of the control during storage. SFA/UFA ratio was significantly reduced in beef roasts with additives, whereas vitamin E vitamers and UFA were higher (p < 0.05) in the roasts with RF/RBO. Beef roasts containing RF and RBO were acceptable to consumers in sensory attributes. Cholesterol autoxidation was examined in an aqueous meat model system with different levels of nonsaponifiable fraction from rice bran (0, 700, 1400, and 2100 ppm). The effect of nonsaponifiable fraction was determined at 4 h intervals for 16 h at pH 5.5 and 80°C. Increased oxidation time reduced (p < 0.05) total vitamin E vitamers and cholesterol concentration. Oryzanol was not significantly reduced with the 2100 ppm treatment after 4 h cholesterol oxidation. An increase in the nonsaponifiable fraction resulted in a decrease (p < 0.05) in the formation of 7-ketocholesterol. The highest level of additive (2100 ppm) was the most effective in inhibiting cholesterol autoxidation; the order of inhibition was 91.7% (2100 ppm) > 81.8% (1400 ppm) > 63.1% (700 ppm).

ISBN

9780599548701

Pages

112

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