关键词: 柿果, CO2脱涩, 酚类物质, 抗氧化能力

Abstract: In our present experiment, persimmon fruit were treated with CO2 for different periods of time (0, 12, 20, 28, 36 and 44 h) for the removal of astringency, and the physicochemical properties, the contents of sugar, total phenolics, total flavonoids and tannic acid and antioxidant capacity during the de-astringency process were investigated. The results showed that treatment time had no obvious influence on the hardness, water content, water activity, pH or carbohydrate content of persimmon fruit. However, the soluble solid value and total phenolic content exhibited significant downward trends with increasing treatment time. Through gradient ultrafiltration, the phenolic compounds were separated into three fractions according to their weight average molecular mass (MW), including high molecular mass phenols (HPs, MW > 10 kDa), medium molecular mass phenols (MPs, 10 kDa > MW > 3 kDa) and low molecular mass phenols (LPs, MW < 3 kDa). The contents of HPs decreased significantly with treatment time (P < 0.05), MPs were not detected, and the contents of LPs were kept unchanged during the process (P > 0.05). Moreover, the 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radical, 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacities and ferric ion reducing antioxidant power of persimmon fruit were decreased by 95%, 96% and 96% after de-astringency treatment, respectively. The results illustrated that the phenolic compounds in persimmon fruit were mainly composed of high molecular mass tannins and low molecular mass polyphenols. High molecular mass tannins were the main contributors to the antioxidant capacities of persimmon fruit, but many of them were lost during the de-astringency process.

Key words: persimmon fruit, CO2 de-astringency, phenolics compounds, antioxidant capacity