Effect of Processing Techniques on Techno-Functional, Thermal, Pasting, and Digestibility Characteristics of Selected Millet Flours

Abstract

Millets such as proso, foxtail, and finger millet are nutrient-dense grains with potential as functional food ingredients. Processing methods like fermentation, germination, and roasting can significantly enhance their nutritional and functional properties, making them suitable for incorporation into a wide range of food products. This study investigated the structural and functional modifications in millet flours induced by fermentation, germination, and roasting. Functional properties (water and oil absorption capacities, solubility), pasting behavior, thermal characteristics, starch digestibility, and protein digestibility were analyzed. Fourier Transform Infrared Spectroscopy (FTIR) was used to confirm changes in functional groups associated with processing. All processing methods improved the functional and digestibility properties of millet flours. Water absorption index ranged from 4.4 to 5.7 g/g and solubility index from 2.0 to 3.5 g/100 g. Oil and water absorption capacities were 1.5–1.9 g/g and 1.6–2.8 g/g, respectively. Pasting viscosities showed peak values between 74.8 and 125.4 cP, final viscosities of 83.4–141.7 cP, setback viscosities of 12.9–62.5 cP, and breakdown viscosities of 4.4–20.7 cP. Thermal analysis indicated onset, peak, and conclusion temperatures of 63.4–85.7 °C, 72.3–92.5 °C, and 79.2–102.3 °C, respectively. Readily digestible starch (14.3–40.7%), slowly digestible starch (38.9–57.7%), and resistant starch (14.7–28.9%) levels were significantly influenced by processing. Protein digestibility improved, ranging from 68.4 to 83.6%. FTIR confirmed the presence of functional groups, including alkane (-CH), hydroxyl (-OH), alkene (=CH), carbonyl (-C=O), and amine (-NH), indicating biochemical modifications. These findings support the potential use of processed millet flours as functional and nutritional ingredients in the development of diverse food products.