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Investigation of Digestibility In Vitro and Physicochemical Properties of A- and B-Type Starch from Soft and Hard Wheat Flour

¹Food Research Program, Agriculture and Agri-Food Canada, 93 Stone Road W., Guelph, ON, Canada N1G 5C9. ²Corresponding author. Phone: 519-780-8030. Fax: 519-829-2600. E-mail: liuq@agr.gc.ca ³School of Food Sci. and Technology, Southern Yangtze University, 170 Huihe Road, Wuxi City, Jiangsu, P.R. China. ⁴Dept. of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada N1G 2W1.

In this study, the functional properties of A- and B-type wheat starch granules from two commercial wheat flours were investigated for digestibility in vitro, chemical composition (e.g., amylose, protein, and ash content), gelatinization, retrogradation, and pasting properties. The branch chain length and chain length distribution of these A- and B-type wheat starch granules were also determined using high-performance anion exchange chromatography (HPAEC). Wheat starches with different granular sizes not only had different degrees of enzymatic hydrolysis and thermal and pasting properties, but also different molecular characteristics. Different amylose content, protein content, and branch chain length of amylopectin in A- and B-type wheat starch granules could also be the major factors besides granular size for different digestibility and other functional properties of starch. The data indicate that different wheat cultivars with different proportion of A- and B-type granular starch could result in different digestibility in wheat products.