A comparative study on the multi-scale, physicochemical properties and enzyme activities of tetraploid cultivated wheat starch with different amylose contents.

Tetraploid cultivated wheat represents a valuable genetic resource for enhancing starch quality in food and industrial applications. Nevertheless, the relationship between its multi-scale structure and biosynthetic regulation, particularly the role of key enzyme activities, remains insufficiently explored. This study systematically examined the multi-scale structure, enzyme activities, and functional properties of starch from six tetraploid wheat varieties differing in apparent amylose content (AAC). The results indicated that AAC ranged from 17.29 % to 25.29 %, showing a positive correlation with granule size and molecular ordering. Notably, variety TS6 exhibited the highest molecular order (degree of order(DO)₁₀₄₇/₁₀₂₂ = 0.441), gelatinization temperatures (onset temperature(To) = 64.47 °C, peak temperature(Tp) = 68.69 °C), and content of slowly digestible starch (SDS = 38.77 %), along with a comparatively high level of resistant starch (RS =11.48 %), which underscores its superior thermal stability and slow digestibility. All starch granules displayed uniform disc-like morphologies with smooth surfaces and typical A-type crystalline patterns. Furthermore, correlation analysis revealed a significant association between AAC and AGPase activity, suggesting that starch biosynthesis plays a regulatory role in amylose accumulation. Enzyme activity data indicate that synergistic interactions among biosynthetic enzymes across varieties, implying that dynamic enzymatic activities modulate the multi-scale architecture of starch-from molecular to granular levels-thereby influencing its physicochemical properties, including digestibility. These insights elucidate the coordinated regulatory role of starch synthases in determining structure and functionality, offering new perspectives for breeding tetraploid wheat varieties with tailored nutritional and functional traits for health-oriented food applications.