Effect of hydrothermal treatments on physicochemical, rheological and nutritional properties of millet: An analytical review

Abstract

Millets, nutrient-rich grains packed with complex carbohydrates, dietary fiber, essential proteins, lipids, and antioxidant phytochemicals, are gaining recognition as valuable dietary components. Various processing techniques, including roasting, extrusion, germination, and hydrothermal treatment, have been employed to enhance nutritional bioavailability and consumer appeal. These processing, which involves the application of heat and moisture, induces specific transformations in millet components. Starch undergoes gelatinization, a process in which its crystalline structure is disrupted, leading to increased digestibility and viscosity. Proteins undergo denaturation, altering their structure and potentially improving their digestibility and functionality. Lipids may also undergo modifications, impacting their stability and interactions with other food components. These changes facilitate the release of bioactive compounds such as phenolics, flavonoids, and tannins. These processes effectively reduce anti-nutritional factors, further boosting nutrient availability. This review provides a comprehensive analysis of various hydrothermal methods, including steaming and heat-moisture treatment, and critically evaluates their impact on the physicochemical properties, nutritional profile, and potential health benefits of millet. Steaming, a gentler method involves cooking millet in a steamer basket above boiling water, preserving its delicate texture and nutty flavor while still promoting starch gelatinization and nutrient retention. Heat-moisture treatment, a more specialized technique, involves exposing millet to elevated temperatures and controlled moisture levels, inducing specific changes in starch properties without causing complete gelatinization. This review examines how hydrothermal methods affect the nutritional and functional properties of millet to inspire the development of innovative, nutritious millet-based food products.