Structure-digestibility relationship of starch inclusion complex with salicylic acid.

Amylose, the linear component of starch, can complex with small molecules to form single helical inclusion complexes of 6, 7, or 8 glucosyl units per helical turn, known as V, V, and V. In this study, starch-salicylic acid (SA) inclusion complexes with different amounts of residual SA were obtained. Their structural characteristics and digestibility profiles were obtained with complementary techniques and an in vitro digestion assay. Upon complexation with excess SA, V type starch inclusion complex was formed. When excess SA crystals were removed, the V polymorphic structure could remain, while further removing intra-helical SA converted the V conformation to V. Furthermore, the digestion rate of the resulted V was lowered as indicated by increased resistant starch (RS) content, which could be due to its tight helical structure, whereas the two V complexes were highly digestible. Such findings could have practical implications for novel food product development and nanoencapsulation technology.