A review: Hydrothermal processing of millets and effect on techno‐functional and nutritional properties

Abstract Millets represent a group of at least 13 highly nutritious, climate‐resilient grain species. Currently being considered as potential replacement to conventional staple food crops, there occurs an urgent necessity for their value addition through processing. Parboiling, heat‐moisture treatment, dry heat processes, and extrusion are the prominent hydrothermal processes for grains. In this article, process principles and research reported on hydrothermally processed millets have been exhaustively reviewed to enable the future positioning of millets in the food industry. Each hydrothermal process is unique and exerts a specific effect on millet properties. Efficiency in the reduction of inherent antinutrient compounds, namely tannins, phytic acid, phenols, and trypsin inhibitors is a key consideration in process designing. Intercomponent interactions in processed millets, namely compound entrapment, Maillard browning, starch–lipid complex, disulfide crosslinking in proteins, protein–lipid complex, tannin–protein complex, and others crucially control the product quality. Processed millet grains and products are established as functional foods, based on biochemical and in vivo studies. The review also identified major gaps in research. With distinct morphological, compositional, and functional differences, each millet variety can be individually dealt for setting process parameters. Being rich in lipid and antioxidant compounds, possibilities for rancidity control need to be examined for stored millet flours. Flours have been mostly used for partial replacement of base flour in developed products. The possibility of using hydrothermally modified millet flours in single flour products can be explored.