Interactions between soluble soybean polysaccharide and starch during the gelatinization and retrogradation: Effects of selected starch varieties

Abstract

This study shows that soluble soybean polysaccharide (SSPS) has different anti-retrogradation effects on different types of starches and demonstrates the mechanism. Maize starch (MS), wheat starch (WS), rice starch (RS) and tapioca starch (TS) were chosen to investigate the pasting and retrograding characteristics with low-field nuclear magnetic resonance (LF-NMR), rapid visco-analysis, X-ray diffraction (XRD), and texture profile analysis (TPA). A 4% SSPS solution lowered the pasting viscosity of starch systems and tightened the interstitial water (T22) that dominated the starch network (LF-NMR). After 14-day refrigeration, XRD results indicated that SSPS reduced the relative crystallinities of MS and WS, increased that of TS, but had little effect on RS. The different interaction patterns between SSPS and starch led to the differences in retrogradation crystal structure and the formation of V-type structures inhibited the starch retrogradation (MS and WS). The minimal anti-retrogradation effect of SSPS on RS can be explained by its small starch granule size and fuzzy original morphology. The special non-porous structure of TS and the possible electrostatic interaction with SSPS might accelerate the retrogradation process. In addition, SSPS could soften the hardness of MS and WS gels but promote the gelatinization of TS (TPA). Confocal laser scanning microscopy (CLSM) images proved the coating capacity of SSPS. Thus, the coating ability of SSPS on starch granules, the competition effect of SSPS on starch for available water, and the possible molecular interactions between SSPS and starch could be responsible for these results.