Master of Science (MS)
School of Nutrition and Food Sciences
Polyphenols are major dietary components in fruits and vegetables. Many research and epidemiological studies have reported that phenolic compounds, such as anthocyanins, may have a protective effect against various degenerative diseases. Phenolics in grape wine have been extensively studied but information on changes of phenolics in wine and vinegar made from other fruit crops is limited, however. This research started with the objective of determining the effect of proteases in preventing phenolic and, specifically, anthocyanin degradation in the ethanolic fermentation of black raspberries to reduce sugar content. The results of this study led to investigations of changes of other polyphenols in persimmons and blueberries during both ethanolic (vinification) and vinegar (acetification) fermentations. Initial results showed that a 1% neutral bacterial protease could retain anthocyanin in open vinification of black raspberries but the protease treatment provided no benefit when a closed fermentation was used. Additional research using closed vinification followed by acetification of persimmons indicated that phenolics were significantly affected by these fermentations. Phenolics in astringent persimmons were significantly degraded during both vinification and acetification while phenolics in non-astringent persimmons actually increased during vinification but decreased during acetification. In blueberries, anthocyanin and epicatechin were increased during vinification but decreased during acetification. The lipid-protective properties of fruit wine and vinegar was also investigated. In this study of antioxidant properties, blueberry vinegar was more effective than blueberry juice or blueberry wine in preventing EPA and DHA degradation in salmon oil-in-water emulsion model system. This thesis research provides informative insights concerning changes in polyphenols, such as anthocyanin, during vinification and acetification of some fruit crops. The information is especially beneficial to the juice, wine and vinegar industries since polyphenols are one of the major health promoting constituents in fruit juices, wines and vinegars.
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Tan, Yen-Ping, "Changes in select phenolic compounds during ethanol fermentation and acetification of raspberry, blueberry and persimmon" (2011). LSU Master's Theses. 3059.