Effect of blanching on fermentation performance and flavor quality of pineapple fruit wine

Pineapple fruit wine was prepared by constant temperature (22±1) ℃ fermentation process using fresh pineapple as the test material in this study. Using pineapple wine fermented with the unbleached pulp as the control, the effects of blanching treatment (95 ℃, 120 s) of fruit pulp on the quality indexes, antioxidant activity and volatile flavor compounds of pineapple fruit wine was investigated by measuring the sugar, acid, total polyphenol contents, and the antioxidant activities during pineapple fermentation process. The results showed that the sugar content of pineapple fruit wine decreased to less than 4.0 g/L during the fermentation, the total acid, total polyphenol contents, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rates and Ferric ion reducing/antioxidant power (FRAP) value increased first and then tended to be stable. Blanching treatment caused a lag in the glucose reduction rate of pineapple fruit wine, extended fermentation time for 4 d, and the contents of total phenol and ascorbic acid, DPPH scavenging rates and FRAP value during the fermentation were significantly lower than those of control group (P<0.05). A total of 24 volatile flavor components (11 alcohols, 5 esters, 5 acids, 2 aldehydes and 1 ketone) were detected in the pineapple fruit wine samples, among which no ethyl formate and ethyl caproate were detected in the control group, and no furfural and 3-hydroxy-2-butanone were detected in the blanching treatment group. The types of esters in pineapple fruit wine were increased by blanching, but the contents of ethyl acetate and ethyl lactate were decreased by 26.1% and 91.8%, respectively. Blanching of pineapple pulp made pineapple fruit wine more harmonious and mellow in taste.