Investigation of the main parameters during the fermentation of Chinese Luzhou-flavour liquor

Abstract

The aim of this study was to investigate the evolution of some physicochemical properties of fermented Zaopei throughout the fermentation. For each layer of Zaopei, the temperature gradually increased to a maximum after about 2weeks, and then remained stable for about 15days before it began to decrease; acidity tended to increase during the entire fermentation, while the starch content decreased throughout the fermentation. The reducing sugar content for all layers reached a maximum after one week and decreased afterwards. Ethanol accumulated with time and reached a peak after 5weeks for each layer, then tended to decrease but rose again slightly after 7weeks. The moisture content in the top and middle layers increased gradually and reached saturation after 5weeks, then remained almost unchanged, while the moisture of the bottom layer increased throughout the fermentation. The ethyl caproate, ethyl acetate and ethyl butyrate content of all layers remained almost constant for the first 2weeks, then increased gradually and reached a maximum after 6weeks, and subsequently declined slightly. The ethyl lactate of each layer increased throughout the fermentation. The caproic acid, acetic acid, butyric acid and lactic acid in all of the layers reached the highest level on the sixth week, followed by a continuous decrease until week 8, thereafter followed by a slight increase in trend. Additionally, the qualities of the raw liquor distilled from the different layers of Zaopei were investigated and the results demonstrated that the bottom layer possessed the best quality.