Abstract: This study systematically compared the structure and physicochemical properties of starch in core flour, break flour, and straight-grade flour from three wheat varieties. The particle size, gelatinization characteristics, thermal properties, short-range order structure, and crystal structure were analyzed to comprehensively characterize the composition, thermal response behavior, and multi-scale structural features of the starch. The results showed that the starch in break flour had higher levels of B-type starch, pentosan, and ash, while the starch in core flour exhibited higher amylose content, crystallinity, and short-range order than did that in the other flours. With respect to functional properties, core flour starch performed excellently in terms of paste transparency, swelling power, gel strength, and viscosity parameters, with superior freeze-thaw stability. Correlation analysis further revealed that the relative content of B-type starch was a key structural variable which determined the differences in gelatinization temperature, viscosity formation and gel properties. This study clarifies the structure-function relationship of starch in different mill streams, providing a theoretical basis for the precise design of starch-based functional flour, the hierarchical utilization of wheat resources, and the development of specialty flour.

Key words: wheat mill streams; starch; multi-scale structure; functional characteristics; correlation analysis