Antioxidant Properties of Muscadine Grape Products

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Title: Antioxidant Properties of Muscadine Grape Products
Author: Vaughan, Trivette Lashum
Advisors: Dr. Leon Boyd, Committee Chair
Abstract: Phenolic compounds present in grapes and wines may play a positive role in human nutrition, related to their positive protective action towards reducing the risks associated with heart disease and the scavenging properties toward free radicals associated with degenerative diseases. Noble and carlos grapes were either cold pressed at room temperature or hot pressed at 43 C followed by collection of their free run juices and fermentation to wines. Resulting pomaces were dried at 37 C, 49 C, and 60 C by convection and vacuum ovens. Juices, wines and pomaces were tested for total phenol content and antioxidant capacity via the oxygen radical absorbance capacity assay (ORAC). Carlos grape skin, seed and delipidized seed extracts were analyzed to determine their antioxidant activity in a safflower oil model system. Carlos grape skin and seed were dried at 60 C and extracted using ethyl acetate and water. The antioxidant activity of carlos grape extracts were compared to tert-butyl hydroquinone (TBHQ) and propyl gallate (PG). Three levels (60, 180 and 300 milliequivalents of gallic acid) of extract were tested in an oil model system using the oxidative stability instrument (OSI) and conjugated diene, to measure levels of antioxidant activity. The objective of this research was to study the effects of processing on muscadine juices, wines and pomaces and to study the antioxidant properties of muscadine extracts in a lipid model system. Results of processing effects indicated that noble hot pressed juice and noble wine showed a significantly higher level of total phenols and total antioxidant capacity than for carlos samples. Total phenols indicated that all noble pomaces were significantly higher than carlos pomaces. Antioxidant capacity indicated no significant difference between noble and carlos dried samples. Analysis by OSI showed that ethyl acetate seed extracts at a level of 300 milliequilvalents of gallic acid was significantly higher than TBHQ and PG. Oxidative index values for water extracts were not significantly different from TBHQ and PG. Addition of both extracts into the oil model system using OSI index indicated increasing antioxidant activity with increasing concentration of extracts added.
Date: 2003-04-10
Degree: MS
Discipline: Food Science

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