A study on Australian sorghum grain fermentation performance and the changes in Zaopei major composition during solid-state fermentation

Abstract

Sorghum is an essential raw material traditionally used for baijiu production by solid-state fermentation (SSF). China imports Australian sorghum for animal feed and for baijiu production. Determination of the sorghum characteristics specific for baijiu production will enable target breeding for such purpose. This study used five Australian grain sorghum varieties and one Chinese variety for baijiu solid-state fermentation in order to determine the grain sorghum properties most suitable for ethanol production. Ethanol content was highly correlated with the grain total starch content (TS) (r = 0.675, p < 0.05), amylopectin (AP) content (r = 0.590, p < 0.05), C/N ratio (r = 0.837, p < 0.001) and crude protein content (r = −0.813, p < 0.01). This study concluded that the grain sorghum variety that produced high ethanol content, had higher TS, AP and C/N ratio but lower crude protein content. Changes in grain composition during fermentation was also studied. SSF involved the consumption of mainly amylopectin instead of amylose and non-resistant starch instead of resistant starch irrespective of sorghum variety. All fermented samples were found to have increased protein content.