Materials and Sample Collection

Six sorghum varieties, namely, JiNiang 2 (JN-2), JinNuo 3 (JN-3), JiZa 127 (JZ-127), JinZa 34 (JZ-34), LiaoZa 19 (LZ-19), and JiaXian sorghum (JX), were used (Supplementary Figure 1). These varieties were divided into two genotypes. JN-2 and JN-3 are waxy sorghums with low amylose contents (not exceeding 10%) (Yang et al., 2018). JZ-127, JZ-34, LZ-19, and JX are non-waxy sorghums with high amylose contents. Supplementary Table 1 shows the quality properties, including starch, protein and fat contents, of the six sorghum grain varieties.

In May 2019, sampling was conducted during fermentation at Xifeng Liquor Limited Liability Company in Fengxiang Town, Shaanxi Province, China (N34°26′6.74″, E107°29′52.51″). Three paralleled fermentation pits were selected for fermented grain sampling. The fermented grain samples were collected with a special sampler (a tweezer-like tool with spoon-like heads and sharp edges) from the middle of the pits and the upper, middle and lower parts of the four pit corners. The samples were then mixed to form one sample. The fermented grain samples were collected after fermentation for 1, 3, 6, 9, 12, 15, 18, 21, 24, and 26 days. Finally, the samples were transported to the laboratory on ice and kept at −80°C.