Effects of extrusion cooking on nutritional and health attributes of sorghum and millets: special reference to protein and starch digestibility

Abstract Millets, including sorghum grain, are gaining global interest for their rich nutritional profile and potential to develop healthy staple foods. They also have a propensity for low protein and starch digestibility and are high in polyphenolics. These properties provide challenges for designing nutritious and consumer-acceptable foods from sorghum that meet the needs of those under energy/protein malnourishment. In contrast, the high nutritional and polyphenolic profiles and low digestibility make sorghum the ideal grain food to assist those over-energy, malnourished and at risk of obesity and related chronic diseases, including those linked to oxidative stress. Sorghum lacks gluten-forming proteins; therefore, producing sorghum foods with desirable textures is challenging. Extrusion cooking of sorghum may be one processing solution to overcome these barriers and design staple ready-to-eat food products with consumer acceptability. This paper critically reviews the current state of knowledge on the influence of extrusion cooking on protein quality and starch digestibility of sorghum and millet-composite extruded foods.