Degree of Milling on Proso Millet: Exploring the Impact on Engineering, Physicochemical, Thermal, and Microstructural Properties of Fractions

This study explores the physical, engineering, thermal, functional, and structural properties of Proso millet (Panicum miliaceum
L.) fractions produced through systematic dehulling and polishing. Physical assessments showed notable differences in bulk
density, true density, and porosity, underscoring their implications for grain handling, milling performance, and equipment
optimization. Bran fractions demonstrated lower bulk density and increased porosity, while polished grains exhibited reduced
thousand-kernel
weight. Nutritional profiling indicated a significant decline in protein, fat, ash, and dietary fiber with increased
polishing intensity, confirming the nutrient-rich
nature of the bran and germ layers. Functional evaluation using solvent retention
capacity (SRC) revealed that bran fractions had elevated water, sodium carbonate, sucrose, and lactic acid retention values,
reflecting superior hydration, pentosan content, and protein functionality—important for processing and end-use
quality.
Thermal analysis by differential scanning calorimetry (DSC) showed higher gelatinization onset and peak temperatures in bran
fractions and higher enthalpy values in polished grains, indicating varying starch crystallinity and starch-lipid-
protein
matrix
integrity. Cooking tests showed that millet polishing significantly reduced cooking time. Scanning electron microscopy (SEM)
images captured the gradual removal of bran and germ components with increasing polishing levels. The findings provide a comprehensive
understanding to guide the efficient processing and value addition of Proso millet in functional and health-oriented
food applications.