咖啡果皮酵素发酵过程中代谢产物与抗氧化功能评价

Study on the Evaluations of Metabolites and Antioxidant Activity during the Fermentation Process of Coffee Peel Jiaosu

以咖啡制作过程中废弃的咖啡果皮为原料,利用咖啡果皮表面微生物,在高浓度糖液环境下制备咖啡果皮酵素。研究发酵过程中代谢产物(总糖、总酸、乳酸、醋酸、乙醇、总酚含量)与抗氧化指标(DPPH自由基清除能力、ABTS+自由基清除能力)之间的相关性,利用主成分分析建立不同发酵时间咖啡果皮酵素的综合指标(comprehensive evaluation index,CEI),确定咖啡果皮酵素发酵状态。结果表明:随着发酵时间的延长,微生物利用糖类等营养物质合成乙醇、醋酸、乳酸等成分,同时使咖啡果皮中的活性物质更好地溶出,蛋白质、总酚含量显著上升,对ABTS+自由基和DPPH自由基的清除能力显著增强;发酵过程中各指标之间具有一定的相关性,其中总酚含量变化趋势与对ABTS+自由基和DPPH自由基的清除能力表现得尤为显著;适当的延长发酵时间有利于提高咖啡果皮酵素综合指标。

Using the surface microbes of the coffee peel, coffee peel jiaosu was prepared with abandoned coffee peel during coffee making process under the high concentration sugar solution environment. The correlation between metabolites (total sugar, total acid, lactic acid, acetic acid, ethanol and total phenol) and antioxidant index (DPPH free radical scavenging ability and ABTS+ radical scavenging ability) during fermentation was studied, and the comprehensive evaluation index(CEI) of the coffee peel jiaosu at different fermentation time was established by using the principal component analysis to determine the fermentation state of coffee peel jiaosu. The results showed that with the prolongation of fermentation time, the microorganisms made use of carbohydrates and other nutrients to synthesize ethanol, acetic acid, lactic acid and other components. At the same time, the active substances in the coffee peel were better dissolved, the content of protein and total phenol increased significantly, and the scavenging ability of ABTS+ free radical and DPPH free radical were significantly enhanced as well. There was a certain correlation among the indexes, among which the total phenol content and the scavenging ability of ABTS+ free radical and DPPH free radical were particularly significantly correlated, and the proper prolongation of fermentation time was beneficial to the improvement of the comprehensive evaluation index of coffee peel jiaosu.