Influences of Household Processing Methods on Nutritional Composition, Anti-nutritional Factors and Antioxidant Activities of Foxtail Millet

Abstract

The present investigation aims to study the influence of household processing methods, such as soaking, germination, and steam cooking, on nutritional composition (proximates, amino acids, minerals, and vitamins), antinutrient factors (phytochemicals: tannins, total phenols, phytic acid; enzyme inhibitors: trypsin and α-amylase inhibitors) and antioxidant properties of whole grains of foxtail millet. The contents of total ash (1.42%), fat (3.02 g/100 g), and mineral chromium (12.83 mg/100 g) were found to be high upon soaking. Trypsin inhibitors were reduced from 26.84% (steam cooking) to 12.45% upon soaking. Germination enhanced the contents of protein (11.57 g/100 g), minerals, i.e., Ca (32.48 mg/100 g), P (5.82 mg/100 g), Fe (5.81 mg/100 g), amino acid tyrosine and vitamin B<sub>1</sub>. A significant decrease in the contents of tannins from 218.93 mg GAE/g (soaking) to 93.93 mg GAE/g), phytic acid from 307.5 mg/g (soaking) to 97.63 mg GAE/g) and α-amylase inhibitors from 35.20% (steam cooking) to 5.61% were recorded upon germination. The TPCs were reduced from 13.63 mg GAE/g (soaking) to 6.81 mg GAE/g upon steam cooking. Germinated grains recorded the highest antioxidant properties based on the scavenging capacity of DPPH (0.59 mg AScE/g), ABTS<sup>+</sup> (10.77 mg TE/g) radicals and RPA (0.89 mg AScE/g). Overall, different household processing methods altered the composition of nutrients, antinutrients, and antioxidant properties. Germination has enriched the bioavailability of protein, carbohydrates, minerals, amino acids, and antioxidant properties and reduced the anti-nutritional factors, especially phytic acid, tannins, and α- amylase inhibitors.