Influence of alkaline fermentation time on in vitro nutrient digestibility, bio- & techno-functionality, secondary protein structure and macromolecular morphology of locust bean (Parkia biglobosa) flour
Caleb Maina Yakubu, Rajan Sharma, Savita Sharma, Baljit Singh
Abstract
Present investigation aimed at evaluating the variation in anti-nutritional factors, phytochemical constituents, bio-functional and technological attributes of locust bean (Parkia biglobosa) flour after alkaline fermentation treatment for different time periods (0, 24, 48 and 72 h). Significant reduction (p < 0.05) in phytate (12.59–5.16 mg/g), saponin (6.87–1.92 mg/g) and tannin (2.86–1.03 mg/g) contents was observed linearly with the fermentation time. Furthermore, in vitro starch and protein digestibility were found to increase from 5.29 to 24.82 g/100 g and 66.47–74.29 g/100 g respectively in response to treatment time. ATR-FTIR spectrum in Amide II region (1600-1700 cm−1) revealed that β-sheet structure prevailed in raw and fermented flours; however, there was significant increase in the α-helix and random coils. Scanning electron micrographs and X-ray diffractograms presented degradation of granular integrity of starch and three-dimensional protein networking. These compositional and structural changes lowered the hydration and emulsification potential while oil absorption and water solubility were found to enhance from 0.86 to 1.01 g/g and 3.16–10.41% respectively. Pearson's correlation matrix showed significant relationship among anti-nutritional factors and nutrient digestibility while principal component analysis validated the differences among variables and observations through two key components of 75.85 and 22.44% respectively.