Effects of oligomeric procyanidins on the retrogradation properties of maize starch with different amylose/amylopectin ratios

The effect of oligomeric procyanidins (OPCs) on the retrogradation of maize starch with different amylose/amylopectin ratios was investigated. The apparent amylose contents in high-amylose maize (HAM), normal maize (NM), and amylopectin maize (APM) starches are 79.05%, 25.43% and 0%. Structural characterizations of retrograded maize starches in the presence of OPCs were conducted by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and nuclear magnetic resonance (NMR). The results suggest that OPCs inhibit the retrogradation of maize starches in low concentrations (1.5-2.5%) with different inhibitory effects for HAM, NM and APM starches. It may be attributed to the variations on interaction ways and binding capabilities between different types of starches and OPCs. The in vitro enzymatic digestion result indicates HAM starch and OPCs have stronger interactions with the formation of resistant structures. These findings provide a further evidence for exploring the interactions between starches and phenolic compounds.