Modulation in the bio-functional & technological characteristics, in vitro digestibility, structural and molecular interactions during bioprocessing of proso millet (Panicum miliaceum L.)

Abstract

The present investigation was carried out to assess the impact of biological processing treatments on compositional, bio- and techno-functional characteristics of proso millet (Panicum miliaceum L.). Soaking (12 h), germination (48 h), fermentation (20 h) and combination of stated treatments were given to healthy proso millet grains and their effect was evaluated on techno-functional properties, anti-nutritional compounds, in vitro starch and protein digestibility, molecular and morphological characteristics. Enzymatic hydrolysis of protein molecules exposed hydrophobic regions which enhanced the oil absorption and emulsification properties. Reductions (p < 0.05) in tannins (73.4–26.5 mg TA/100 g), phytic acid (8.77–2.44 mg/g) and saponins (167–29.1 mg/100 g) occurred after the aforesaid treatments. Scanning electron micrographs confirmed the higher access of starch and proteins to hydrolytic enzymes, thus enhancing their digestibility in treated flours. Fourier-transform infrared spectroscopy and X-ray diffraction pattern revealed that treatments altered the secondary protein structure while their extent was not severe enough to cause drastic damage to crystallinity of starch. Principal component analysis was carried out to validate the differences among bioprocessing treatments. The most severe effect was after combination of germination and fermentation treatments in terms of techno-bio-functionality of the flour as a potential food ingredient.