The multi-scale structures and physicochemical properties changes of wheat starch during high-temperature Daqu preparation process.

High-temperature Daqu, a microbial-rich fermentation starter used in Jiangxiangxing Baijiu production, undergoes complex wheat starch transformations during its preparation. In this study, the multi-scale structure and physicochemical properties changes of wheat starch in high-temperature Daqu making process were investigated by using a variety of analytical techniques. These results showed that the changes of wheat starch during the fermentation process are more significant compared to the storage process. The surface of wheat starch particles was eroded during the fermentation process, resulting in a distinct porous structure. This structural alteration created channels for enzymatic entry into starch granules, facilitating starch degradation and consequently leading to a significant decrease in the molecular weight of starch after fermentation. The annealing effect of starch during high-temperature Daqu fermentation process led to an increase in the relative crystallinity of wheat starch, accompanied by the formation of more V-type crystalline structures. These changes collectively result in significant alterations in the thermal and paste properties of the starch. Additionally, a characteristic selective degradation of wheat starch was observed during the fermentation process, the small-sized starch granules (d < 10 μm) and amylose were preferentially utilized by microorganisms. This study provided a scientific basis for further understanding the change of wheat starch in high-temperature Daqu preparation and its impact on Jiangxiangxing Baijiu production.