Effect of dry heat treatment on the development of resistant starch in rice (Oryza sativa) and barnyard millet (Echinochloa furmantacea)

Abstract

Resistant starch (RS) is that fraction of starch which does not undergo digestion in the human digestive tract. It maintains gut health by acting as a prebiotic and is also known to play an important role in controlling the glycaemicindex of starch‐based foods. The basic structure of RS contributes to its resistance to enzymes. This work focuses on increasing the RS4 content of the selected rice and millet by dry heat treatment. Pan roasting, fluidized bed drying, tray drying, and convective microwave heating methods were utilized to optimize the maximum yield of RS in rice and barnyard millet. Convective microwave heat‐treated samples gave the maximum amount of RS in both rice (26.25 ± 0.14 g/100 g at 180°C, 10 min) and barnyard millet (15.08 ± 0.20 g/100 g at 170°C, 20 min). Therefore, this study concludes that convective microwave heat treatment is more efficient when compared to other dry heat treatment methods in converting starch to RS in both rice and barnyard millet. PRACTICAL APPLICATIONS: This research focuses on the effect of various dry heat treatments on the development of resistant starch in rice and Barnyard millet. Also, optimization of time and temperature combination for maximum yield of resistant starch in convectional microwave heat treatment data may be then scaled up for use in commercial applications. This has high potential for the development of low‐cost conventional technology for the production of high‐quality food products with high resistant starch content, which can be used in the formulation of several functional foods.