30G-32 |
Effects of processing on the antioxidant activity of muscadine juices and wines |
L. C. BOYD1, T. L. Vaughan, A. Banini, and D. E. Carroll. (1) Food Science, North Carolina State University, Raleigh, NC 27695-7624
Fruits and red wines have been shown to be important sources of antioxidants. Several classes of antioxidants are believed to play a key role in protecting foods against oxidation and in preventing several degenerative diseases associated with the production of free radical. However, during the processing of fruits into wines and other processed products, significant losses of antioxidants occur. We hypothesize that through processing, we can improve the retention of antioxidants in processed products including juices, wines, and preserves. Therefore, the objective of this study was to improve the retention of antioxidants in juices and wines by altering processing parameters. Several cultivars of muscadine (Vitus rotundifolia) were pressed under normal conditions at room temperature and at an elevated temperature of 60 C, followed by fermentation with and without contact with the skin for 0, 3 and 7 days. Antioxidant activity was measured by changes in total phenols, oxygen radical absorbance capacity (ORAC), and changes in resveratrol. Results showed that hot processing increased total phenols values four fold ((418 mg/L to 1793 mg/L) with a six-fold increase in ORAC values (0.9 micromoles Trolox equivalents/ml to 5.9 uM/ml). Fermentation with skin showed a similar pattern with phenols increases observed between day 0 and day 3 but decreases by day 7. The ORAC values showed continued increases from day 0, day 3, and day 7. Comparison of stages of maturity showed that muscadines lost antioxidant activity with increasing maturity. Examination of muscadine pomace following the pressing of grape revealed significant amounts of antioxidant activity remaining within the skin and the dried seed. These results are significant in that they demonstrate that by altering traditional techniques of processing grapes into juice and other products, we can enhance the retention of antioxidants.
Session 30G, Fruit & Vegetable Product: Processed Fruits and Vegetables
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