Effect of fermentation on biochemical and sensory characteristics of sorghum flour supplemented with whey protein

Changes in pH, titrable acidity, protein, non-protein nitrogen, total soluble solids, protein fractions and in vitro protein digestibility were investigated during fermentation and/or after supplementation of sorghum flour with whey protein. The pH of the fermenting material decreased sharply with a concomitant increase in the titrable acidity. The total soluble solids increased with progressive fermentation time. The crude protein and non-protein nitrogen both increased with fermentation time. The protein content and fractions were significantly (p ⩽ 0.05) increased after supplementation with whey protein. The albumin plus globulin fraction increased significantly (p ⩽ 0.05) during the first 8 h of fermentation after supplementation with 5% whey protein. Other fraction contents were observed to fluctuate during the fermentation time. Supplementation of the cultivar flour with 10% whey protein greatly increased the protein content as well as the albumin plus globulin fraction while other fractions were significantly decreased. The in vitro protein digestibility was significantly (p ⩽ 0.05) improved during fermentation and even after supplementation. Sensory evaluation of locally processed sorghum products (Kisra, Asida and Nasha) before and after supplementation showed no difference between the supplemented samples and the control ones as judged by trained panellists.