Abstract: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 compre－hensive evaluation index of coffee peel jiaosu.