Cooking fat types alter the inherent glycaemic response of niche rice varieties through resistant starch (RS) formation

Abstract

Studies over the decades highlighted the role of lipids in modulating inherent glycaemic response of rice, still much needed to elucidate how the chain length and saturation of fatty acid (FA) influence this. Hence in this study, we investigated the in vitro glycaemic response, starch-lipid complexing ability and resistant starch (RS) formation in three rice types [white rice (WR), black rice (BR) and red rice (RR)] cooked with four fats [ghee, coconut oil (CO), virgin coconut oil (VCO) and rice bran oil (RBO)], with three cooking conditions (‘before’, ‘during’ and ‘after’). Inherent glycaemic response was found least in RR (81.9%) and among the fats used, RBO rich in long chain unsaturated FA (72.6%) further reduced the least glycaemic response with maximum complexing ability and enriched RS content. Cooking conditions also resulted significant variation in the parameters studied, the most significant effect with complexing ability (28.67%) and RS (2.26%) observed when RBO added ‘during’ with RR. FTIR fingerprint within 950 to 1200 cm−1 region validated the complex interactions of amylose among FA, alcohols and acids present in the RBO. This is the first report proposing a ‘lipid induced resistance towards glycaemic response’ model highlighting the importance of FA type towards modulating the molecular configuration, complexing ability and RS-V formation.