Towards functional food development: impact of extrusion cooking on phenolic compounds and antinutrients in sorghum and millets

Millets and sorghum are important, climate-resilient, and sustainable crops rich in bioactive compounds which provide health benefits by reducing oxidative stress and lowering the risk of chronic diseases. Despite these benefits, the presence of antinutrients such as tannins, phytates, oxalates, and enzyme inhibitors limits nutrient absorption and bioavailability. This review comprehensively evaluates current research on the impact of extrusion cooking, a high-temperature, high-pressure processing with shear force, on the bioactive composition, antioxidant capacity, and antinutritional factors in sorghum and millets. Across studies, extrusion has been shown to reduce total phenolics by approximately 30-40%, decrease antinutrients by 25%-85%, and substantially lower trypsin inhibitors, while, in some cases, retaining 50%-60% of total polyphenolics and antioxidant activity, depending on grain type and processing conditions. Optimizing extrusion parameters is therefore critical to achieving a balance between preserving bioactive compounds and minimizing nutrient losses. Through a comprehensive synthesis of existing research, this review enhances understanding of the transformations occurring during extrusion and discusses processing conditions as key factors driving these inconsistencies. These insights facilitate the formulation of value-added millet and sorghum-based products, while also contributing to broader goals of enhancing nutrition security and reinforcing sustainable and resilient food systems.