Starch digestibility and glycaemic index of selected Indian traditional foods: Effects of added ingredients

The prevalence of type 2 diabetes is increasing rapidly across the world, particularly in Asian countries. This has necessitated the development of hypoglycaemic foods. In this study, the effect of selected ingredients such as barley, oats, gluten, and guar gum on in vitro starch digestibility and in vitro glycaemic index (GI) of four Indian traditional foods (idli, dosa, upma, and chapatti) was investigated. Barley and oats were added at levels of 1–9 g/100 g flour, while gluten and guar gum were added at levels of 1–5 g/100 g flour. An increase in the content of all the four ingredients increased the slowly digestible and resistant starch while decreasing the rapidly digestible starch in all the products under study. A linear decrease in GI was observed with an increase in the levels of added ingredients. Oats and guar gum were more effective in reducing starch digestibility and GI. Oats at 9 g/100 g flour and guar gum at 5 g/100 g flour decreased the GI of idli by 22.67 and 15.82%, of dosa by 17.79 and 17.76%, of upma by 15.43 and 16.59%, and of chapatti by 19.88 and 18.08%, respectively. A strong positive correlation was observed between GI and RDS, while GI showed a strong negative correlation with SDS and RS.