| Summary: | 碩士 === 中臺科技大學 === 食品科技研究所 === 103 === Vitis vinifera L. (common grapevine, European grape) has been used as a food and a beverage, as well as a remedy against various complaints in traditional medicine worldwide since ancient times. The chemical composition and biological activities of the fruit and seed of the grape have been extensively investigated. However, the studies conducted on biological effects of the leaves are limited. Grape leaves are used in the cuisines of a number of cultures. They are most often picked fresh from the vine and stuffed with a mixture of rice, meat, and spices, and then cooked by boiling or steaming. In Indian, grapes leaves are used as a folk remedy for the treatment of diarrhea and vomiting. In the light of these findings, we carried out this study to evaluate the antioxidant activity of the aqueous infusion of Vitis vinifera leaves that treated by different processing methods.
Grapevine leaves of Vitis vinifera L. cv., ‘Kyoho’ and ‘Huangjin’ used for the study were taken from shoots grown in vitro culture. The fresh grape leaves were treated by freeze-drying, steaming, twisting and fermentation, and dry them at different temperatures. The phenolic compounds content, color and antioxidant properties of infusionts from grape leaves were compared.
The results showed that the antioxidant activity of infusions from Kyoho grape leaves were better than that of Huangjin grape leaves. In ABTS free radical scavenging capacity, grape leaves treated by freeze-drying exhibited the strongest antioxidant activity, followed by leaves treated with steaming and then drying at 50℃ oven. EC50 values were 38.9 and 54.5µg/ml, respectively. The scavenging effects of grape leaf infusions on DPPH radicals were similar to the results obtained in ABTS system. The scavenging effects on free radicals and antioxidant activity of grape leaf infusions were correlated well with their content of total phenolic compounds. The lightness of infusion from grape leaf treated by drying at 105℃ oven was decreased ccompared to the other processing methods .
According to the data obtained in the study, the antioxidant activities and phenolic compounds content of grape leaf infusion were varied depending on the processing methods. Grape leaves treated by freeze-drying or steaming and then drying at 50℃ oven showed better antioxidant activities. Overall results suggest that grape leaf infusion has well antioxidant properties and has potential as a functional drink.
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