Impact of crystalline structure on the digestibility of amylopectin-based starch-lipid complexes

In this study, chain-elongated waxy corn starch (mWCS) was complexed with lauric acid (LA) to produce starch -lipid complexes (mWCS@LA) with a mixture of B-and V-type crystalline structures. Results from in vitro digestion showed that mWCS@LA had higher digestibility than mWCS, and the logarithm of slope plots of mWCS@LA revealed a two-stage digestion pattern, with digestion rate of the first stage (k1 = 0.038 min -1) being much higher than that of the following stage (k2 = 0.0116 min -1). The complexation between the long branch chains of mWCS and LA formed amylopectin-based V-type crystallites that were rapidly hydrolyzed during the first stage. The digesta isolated from the second stage of digestion had a B-type crystallinity of 52.6 %, and starch chains with degree of polymerization of 24-28 mainly contributed to the formation of the B-type crystalline structure. The results from the present study reveal that the B-type crystallites were more resistant to amylolytic hydrolysis than the amylopectin-based V-type crystallites.