Impact of high-temperature daqu production on the starch structure of three wheat varieties with different granule...

High-temperature daqu, a fermentation starter used in the production of traditional Chinese distilled liquor, is made from wheat grains. However, structural changes in wheat starch during high-temperature daqu production remain unclear. This study investigated starch from three wheat varieties with different granule size distribution throughout the production. Smaller granules (<10 μm) were preferentially utilized as indicated their proportion decreased from 21 to 30 % in raw starch to 8-10 % in mature daqu. The degree of crystallinity of wheat starch increased by 1.2-2.0 %. Gelatinization temperatures increased by 3.78-6.85 °C due to annealing resulting from the conditions of high temperature and moisture during production, while gelatinization enthalpy remained constant. Hydrolysis induced by enzymes generated in daqu reduced starch molar mass substantially, from ∼6 × 10⁷ g/mol to ∼1 × 10⁷ g/mol, whereas chain-length distribution remained unchanged. These results would be helpful for understanding the importance of wheat variety in determining daqu quality.