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.