Effect of Soaking, Roasting and Germination on Nutritional Composition, Colour Characteristics and Functional Properties of Amaranth Seed Flour

Background: Amaranth is a fast-growing, gluten-free pseudo-cereal notable for its high protein, dietary fiber, healthy fats and essential minerals. This study aimed to investigate the impact of various pretreatments on the nutritional composition, antinutritional components, colour and functional attributes of amaranth flour. Methods: Amaranth grains underwent soaking, roasting and germination treatments. The resulting flours were analysed for proximate composition, mineral content, antinutritional factors, colour characteristics and functional properties. Result: Pretreatments significantly affected amaranth flour composition. Soaking slightly increased protein (16.63%) and carbohydrates (62.17%) while reducing moisture, fat, fiber and ash. Roasting raised carbohydrates (69.5%) but decreased other nutrients, whereas germination enhanced protein (17.62%) and fiber (6.39%) with moderate moisture. Minerals such as Ca, K, Mg, Fe and Zn were highest in germinated flour, while P, Fe and Zn increased with roasting. All treatments reduced tannins and phytic acid, with germination being most effective. Soaking increased lightness (L*), roasting increased redness (a*) and yellowness (b*) and both roasting and germination improved functional properties water absorption, solubility and oil absorption while lowering bulk density. Germination proved to be the most effective pretreatment, as it improved nutritional content, decreased antinutritional factors and enhanced functional properties, highlighting its suitability for producing nutrient-dense amaranth flour for various food uses.