Impact dehulling of browntop millet: Its physical and nutritional characterization

The present study investigated the dehulling characteristics of browntop millet using an impact force-based method, with a focus on the effects of grain moisture content (8, 10, & 12%), impeller operating speed (1100, 1250, & 1400 rpm), and number of passes (NoP) (3, 5, & 7 passes). The responses included dehulling efficiency (DE), head yield (HY), percentage of broken (PoB), milling efficiency (ME), and grain loss (GL). With the increase in impeller speed from 1100 to 1400 rpm, the DE increased from 72.67% to 94.87% while the HY reduced from 57.24 to 38.54%. The optimized levels of the variables were found as 12% moisture content, 1234.93 rpm of impeller speed, and 5.94 NoP, while the DE, HY, PoB, ME, and GL obtained at the optimized levels were found as 76.98%, 42.57%, 3.51%, 70.89%, and 10.81%, respectively. Multivariate analysis was conducted to understand the correlation between the responses. It showed a positive correlation between ME and DE, and an almost null correlation between ME and PoB. The research also examined the alteration in physical properties, proximate composition, anti-nutrients, and functional properties of the grain. The tannin and phytate content reduced after dehulling from 0.64 to 0.26 and 1.04 to 0.81 mg g⁻¹, respectively. Statistical analysis revealed that the operating factors significantly impacted dehulling characteristics and suggested that impact dehulling offers an effective and efficient approach to processing browntop millet.