The relationship between fine structure and physicochemical properties of starches from wheat (<i>Triticum aestivum</i> L.) varieties

Considering the impact of geographic location on starch properties, this research investigates the relationship between fine structure and physicochemical properties of starch isolated from three wheat varieties (Pw1, Sw2, and Hw3) cultivated in Pakistan. The starch granules displayed a range of morphologies, including large lenticular and irregularly disk-like forms as well as smaller oval shapes. Among the starches, Sw2 exhibited the lowest amylose content, while Pw1 showed the longest average amylopectin chain length and the highest molecular weight. X-ray diffractometer and 13C solid-state nuclear magnetic resonance analyses revealed typical A-type diffraction patterns in all three starches, with Pw1 having the highest relative crystallinity. FT-IR results indicated that Pw1 possessed the most ordered structure, as reflected by the highest R1047–R1022 ratio. Findings of differential scanning calorimetry showed that Pw1 had an elevated gelatinization temperature, resulting from its high proportion of long amylopectin chains (degree of polymerization [DP] > 37). In contrast, Hw3 displayed the highest peak and setback viscosities because of its substantial proportion of amylopectin short chains. Hw3 also demonstrated the highest water solubility and swelling power because of its high amylose content. All starches exhibited shear-thinning behavior, with Sw2 having the lowest storage modulus in frequency sweep tests. Additionally, Sw2 showed the greatest oil- and water-absorption capacities, which is associated with its low amylose content. Variations in the fine structure of starch account for the distinct physicochemical properties observed among the wheat varieties, playing an essential role in the tailored selection of wheat products based on their characteristics.