The influence of porosity of the grain medium on the flavour formation of Chinese liquor during solid-state fermentation

Abstract

Solid-state fermentation is a unique technology used for Chinese liquor production and the porosity of the grain medium is one of the important characteristics in the process. However, research on the effects of porosity on flavour generation of liquor in fermented grains is rarely reported. Therefore the present paper introduces the concept of porosity from the field of soil studies and establishes a method for determining the porosity of the fermentation grain medium. Based on the practicality in liquor production, the influence of the addition levels of rice husk and the grinding intensity of the raw material on the porosity of the grain medium was studied. On this basis, the process of solid-state fermentation was simulated and the influence of different porosities on liquor flavour production was examined. The results showed that there were obvious differences in the flavour profiles of the fermented grains with different porosities. The most abundant content and species of volatile compounds appeared when the porosity of the fermented grain medium was ~33%. The development patterns of volatile flavour compounds, in both varieties and quantities, were examined in relationship to the porosity of the fermentation medium. Copyright © 2016 The Institute of Brewing & Distilling.