Microstructural characteristics and gastro-small intestinal digestion in vitro of potato starch: Effects of refrigerated storage and reheating in microwave

•Refrigerated storage of cooked potato starch led to lower and slower glucose release in vitro.•Microstructure of refrigerated and reheated potato starch pastes differed from fresh pastes.•Reheating of refrigerated pastes in microwave influences the crystalline perfection in pastes.•Low GI features for starch based foods can be achieved by controlling refrigeration and reheating.

The objective of our study was to evaluate paste clarity, retrogradation (syneresis %), thermal characteristics and kinetics of glucose release during in vitro gastro-small intestinal digestion of freshly cooked and refrigerated potato starch. Freshly cooked starch pastes had a paste clarity of 71%, which decreased to 35.4% whereas syneresis (%) increased after 7 days of refrigerated storage. The X-ray and thermal characteristics of native, retrograded and microwave reheated starch samples differed significantly from each other. For the freshly cooked starch pastes, ∼88% starch hydrolysis was observed at the end (150 min) of digestion under simulated gastro-small intestinal conditions that decreased to ∼70% for the 7 day stored pastes. The hydrolysis (%) of refrigerated pastes increased to 86% and 92% after one and two cycles of microwave reheating, respectively. These results contribute to the understanding of starch retrogradation in relation to starch digestion.