Interplay of germination time, nutritional content, bioactive constituents, antioxidant activity, and in-vitro digestibility in kodo, little, and barnyard millets

Abstract

Kodo, little, and barnyard millets are considered as minor millets. The changes in total starch, amylose and nutritional content, bioactive constituents, antioxidant activity, starch hydrolysis kinetics, in-vitro protein digestibility, in-vitro glycaemic potential, morphology, and molecular interactions caused by different durations of germination treatment in minor millets flour were analysed. The selected millet grains were soaked and germinated at optimized conditions of temperature by standard method for 24, 48, and 72 hours. After the soaking-germination treatment, starch content of each of the selected millet flour decreased significantly (p < 0.01) with the maximum decrease after 72 hours. A significant (p < 0.05) increase in bioactive constituents and antioxidant activity assessed by DPPH RSA, FRAP, and ABTS was observed in each of the three millet flour during germination from 24 to 72 h. After soaking and germination the in-vitro protein digestibility and in-vitro glycaemic potential increased significantly (p < 0.05, 0.01). The reduced ratio of crystalline and amorphous region, particularly after 24 & 48 h of treatment in the selected millet flour suggested the loss of ordered structure. Principal component analysis revealed interactions between matrix constituents and functional properties in minor millet flours and grouping in terms of analysed properties of minor millet flours with respect to different time duration of soaking-germination treatment.