Effect of fermentation on protein fractions and in vitro protein digestibility of maize

Changes in pH, titratable acidity, total soluble solids and protein of maize during natural fermentation at 37°C up to 36 h were monitored. The pH of the fermenting material decreased sharply with concomitant increase in the titratable acidity. Total soluble solids increased with progressive fermentation time. The crude protein and non-protein nitrogen increased during the first stages of fermentation. The in vitro protein digestibility markedly increased as a result of fermentation. The globulin and albumin fraction increased significantly (P⩽0.05) during the first 16 h of fermentation. The zein fraction was the major protein fraction, which decreased during the first 16 h of fermentation but increased sharply with progressive fermentation. G1-glutelin increased during the first 16 h but fluctuated thereafter. The G2-glutelin, which is the minor fraction and G3-glutelin the second most abundant fraction, together with insoluble protein, fluctuated during the fermentation process. The results indicated that natural fermentation of corn significantly improves in vitro protein digestibility.