Sub-High amylose maize starch: an ideal substrate to generate starch with lower digestibility by fermentation of Qu.

BACKGROUND: Fermentation of Qu (FQ) is a novel method to modify starch's properties, expanding its application, especially in increasing resistant starch (RS) content. However, although using waxy maize starch (WMS) as fermentation substrate can increase RS content significantly, it may be time-consuming and not cost-effective due to almost negligible native RS content of WMS. To solve this problem, we hypothesized that sub-high amylose starch (s-HAMS) which amylose content closes to 50% may be an ideal substrate for FQ.

RESULTS: The results showed FQ did not change the shape and the particle size of starch granules, gelatinization peak (Tp ) and conclusion temperature (Tc ), while slowly digested starch (SDS) content saw a declining trend and rapidly digested starch (RDS) content fluctuated during FQ. And the amylose content decreased within 36 h then increased; the RS content, relative crystallinity (RC), the ratio of 1047 cm-1 /1022 cm-1 , the diffraction peak at 19.8° in XRD and the gelatinization onset temperature (To ) increased significantly, within 24 h of FQ. However, after 24 h of fermentation, RS content, RC, the ratio of 1047 cm-1 /1022 cm-1 and gelatinization enthalpy (ΔH) saw a significant decreasing trend.

CONCLUSION: We suggested that s-HAMS is more suitable for FQ with short time to produce low digestibility starch, and the increase of RS may be due to the formation of 'amylose-lipid' complexes (RS5). This article is protected by copyright. All rights reserved.