Effects of heat moisture treatment on the structure and digestibility of high amylose starch-lauric acid complexes

In this study, we investigated the effects of heat moisture treatment (HMT) on the structure and in vitro digestibility of high-amylose starch-lauric acid complexes, revealing the relationship between the effects of moisture content (MC) and fine structure in vitro digestibility of the complexes. The results showed that HMT changed the structure of the complexes, while MC significantly affected the resistant starch content, complex index, and relative crystallinity of the complexes. Compared with complexes without HMT, complexes prepared at 25% MC had the highest resistant starch content (63.97%), complex index (75.77%), and relative crystallinity (15.28%). The Fourier transform infrared spectroscopy results showed that the short-range order of the complexes was affected by the MC, particularly at 25% MC, which exhibited the highest short-range order among the complexes. Nuclear magnetic resonance spectroscopy results showed that the high amylose starch-lauric acid complexes prepared at an MC of 25% had a high V-shaped single-helix complex, which belonged to the V6-type crystalline structure. Small angle X-ray scattering data further indicated that complexes at this MC displayed a tighter structure with a larger lamellar thickness (dc) in the crystalline region. Therefore, we believe that the MC altered the fine structure of the complexes, which in turn affected their in vitro digestibility.