Germination Led Enhancement in Nutritional Properties of Proso Millet

Abstract

Proso millet (PM), one of the millets is known to possess a high protein and bioactive content. However, it also does hold a good amount of anti-nutrient content (ANC) like tannin, saponin, and phytic acid. Which along with impeding the digestibility of protein, starch and minerals, add bitter tastes to the food. Germination, a traditional bioprocess technique aids in decreasing the ANC. Germination of PM was carried out at different times (24, 48, 72 h) and temperatures (20, 25, 30°C). The total polyphenol and flavonoids content was found to range from 1.2 ± 0.11 to 2.84 ± 0.03 mg GAE/g DW and 183.04 ± 35.6 to 388.66 ± 6.96 μg QE/g DW, respectively. In a similar fashion DPPH radical scavenging and FRAP activity ranged between 0.35 ± 0.012 to 0.46 ± 0.012% and 570 ± 53.90 and 3025 ± 75.78 μg AAE/g DW. There was a rise in protein and free amino acid content with increasing germination period and temperature from 19.99 ± 0.19 to 35.08 ± 2.17 mg BSAE/g DW and 3.25 ± 1.74 to 12.81 ± 13.1 mg LE/g DW, respectively. Owing to a decrease in the ANCs like tannin, saponin and phytic acid from 715.66 ± 66.59 to 503.84 ± 33.29 mg TAE/g DW, from 147.78 ± 7.75 to 88.69 ± 4.09 μg DE/g DW, and from 7.51 ± 0.10 to 6.05 ± 0.06 mg/g DW. Besides the decrease in ANCs, there was a decrease in starch content from 73.33 ± 2.5 to 57.83 ± 3.14 mg/g DW and a simultaneous increase in reducing sugar from 17.03 ± 0.66 to 139.28 ± 22.84 μg GE/g DW due to increased enzyme activity during germination. The rise in bioactive compounds led to increased antidiabetic potential by increasing % α-amylase inhibition capacity from 86.27 ± 19.41 to 134.91 ± 58.39.