Digestibility and supramolecular structural changes of maize starch by non-covalent interactions with gallic acid

Abstract

The effects of non-covalent interactions between gallic acid (GA) and starch on starch digestibility and supramolecular structural changes (short-range ordered molecular structure, crystalline structure, lamellar structure and fractal structure) were investigated. The results indicated that the digestibility of both starches was substantially reduced in the rapidly digestible starch (RDS) content, but resistant starch (RS) was increased after interacting with GA. The RS content of starch-GA complexes ranged from 17.70 to 50.02%, which is much higher than that of high amylose starch (G50) (11.11%) and normal maize starch (NMS) (4.46%). Compared with native starches, starch-GA complexes possess more ordered and compact structures; furthermore, G50-GA complexes possessed more compact scattering objects, thicker crystalline lamellae and thinner amorphous lamellae than those of NMS-GA complexes. This revealed that more ordered multi-scale structures promote the RS formation. Docking studies were conducted to reveal the mechanism of digestibility variations. It showed that GA would non-covalently interact with starch molecules and contribute to ordered structure formation to somewhat extent; meanwhile, GA had higher binding affinities to α-amylase than to starch chains; during the hydrolytic process, GA could be released from the complex and was more likely to occupy the active sites of Asp197, Asp300, His299 and Glu233 by hydrogen bonds and van der Waals forces, which kept starch out of the active site pocket and reduced starch digestibility. These results demonstrate that the non-covalent interactions between GA and starch could be a promising method of controlling starch structures and starch digestion behaviors.

Modulating the in vitro digestibility and predicted glycemic index of rice starch gels by complexation with gallic acid

“…0.65 nm −1 was disappeared for all the starch samples due to the complete disruption of multi-scale structures of starch granules after hydrothermal treatment. According to the literature, the SAXS intensity at low-q region was correlated with the difference in the electron density between ordered and amorphous regions (Chi et al, 2017;Suzuki, Chiba, & Yano, 1997). It can be seen that the intensity of RSG-1 and RSG-2 at low-q region was higher than that of RSG, indicating RSG-1 and RSG-2 had a larger difference in the electron density between ordered and amorphous regions.…”

“…Nevertheless, there is insufficient knowledge on whether and how dietary phenolics such as GA can vary the hydrogen-bonding network and the ordering of starch. In our previous research, we found that GA could alter the starch semi-crystalline structure by interacting with starch in a non-covalent way, which decreases the starch digestibility (Chi et al, 2017). However, phenolic compounds have been reported with the potential of inhibiting starch retrogradation rather assisting starch reassembly (Wang, Li, Copeland, Niu, & Wang, 2015).…”

Multi-scale structure, pasting and digestibility of adlay (Coixlachryma-jobi L.) seed starch

“…Therefore, ASS had the highest degree of crystallization which follows the orders of ASS > MS > PS. According to previous studies (Chi et al, 2017;Lopez-Rubio, Flanagan, Shrestha, Gidley, & Gilbert, 2008),…”

“…In order to further clarify the structural parameters of semi-crystalline lamellae, one-dimensional correlation function profiles were calculated according to following equation (Chi et al, 2017;Kuang et al, 2017)…”

“…And the hierarchical structures of starch granules have been confirmed to be the critical determinant of starch functionalities for food processing and human nutrition (Chi et al, 2017). Thus, understanding the relationships between hierarchical structures and functional properties (e.g.…”