Abstract:To investigate the mechanism of the impact of the structure of lotus seed resistant starch on digestibility, lotus seed starch was modified using different physical treatments (autoclaving, ultra-high pressure, microwave) combined with pullulanase. The results showed that the particle size of the modified lotus seed starch increased, the surface of the particles was rough and formed irregular lumps, the “Maltese cross” formation disappeared, the relative crystallinity (from 31.02% to 18.19%) and short-range ordering (1.56 to 0.97) significantly decreased (P<0.05), and the crystalline type changed from C-type to B-type. In vitro digestion experiments confirmed that starch treated with ultra-high pressure combined with enzymatic modification contained the highest content of high-resistant starch (56.50%). The digestion properties of lotus seed resistant starch were significantly correlated with the branched amylose chain length distribution and the short-range ordering structure and crystalline structure. The increase in short-range ordering, relative crystallinity, and B1 chain and B2 chain content of the starch molecules was conducive to the enhancement of the resistance of lotus seed resistant starch to enzymatic hydrolysis, which may be related to the regulation of digestive properties. The relationship between the multiscale structure of modified lotus seed starch and its digestive properties, were analyzed herein to provide a reference for the preparation of lotus seed resistant starch with strong anti-digestive ability using novel food processing technology, and to guide the production of low-GI lotus seed starch food with hypoglycemic function.
