Effects of the ratio of grain to rice husk on the physicochemical property and volatile flavor compounds of strong-flavor Baijiu Zaopei

The blending process of raw materials based on the appearance observation of Zaopei (fermented grains) is the key link of traditional process of strong-flavor (Nongxiangxing) Baijiu, which has an important impact on the yield and quality of the original Baijiu production. In this study, solid- state fermentation of strong-flavor Baijiu was simulated at the laboratory level, and the effects of the ration of grains to fermented grains, and the ratio of grains to rice husk on the physicochemical properties and main volatile flavor substances of Zaopei were investigated by conventional detection method and headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results showed that the different ratios of grains to fermented grains, and grains to rice husk had a significant effect on the moisture, acidity and starch content of Zaopei (P>0.05). A high ratio of grains to fermented grains (>25%) or a high ratio of grains to rice husk (>20%) would result the residual starch content of Zaopei greater than 15%, which was not conducive to full fermentation. The HS-SPME-GC-MS results showed that a total of 7 important alcohol and ester volatile flavor substances were detected in Zaopei with a ratio of grains to fermented grains 20%-25% after the fermentation, which were higher than those of other experimental groups. Appropriate ingredients of grains and rice husk were important prerequisites for ensuring the normal fermentation of Zaopei and the production of rich and coordinated flavor compounds.