A co-fermentation technology based on small peptide production and protein structure modification increases the edible value of corn gluten meal

Although corn gluten meal (CGM) is rich in protein, its application in the food industry is limited because it contains high concentrations of zein and an unbalanced composition of amino acids. In this study, probiotics and keratinase were used to conferment a corn gluten-wheat bran mixture (CGW) with wheat bran as the carbon source. After fermentation under optimal conditions, the TA-SCP content of CGW was increased from 1.61% to 22.67%, and the small peptide yield reached 52.90%. After fermentation, the contents of essential amino acids and free amino acids in CGW increased significantly. The macromolecular proteins in CGW were effectively degraded, intermolecular force of proteins was decreased, α-helixs and random coils were transformed to β-sheets and β-turns. Animal experiments showed that both fermented CGW (FCGW) and wet fermented CGW (WFCGW) products significantly increase the crude protein digestibility, trypsin activity and amino acid transporter mRNA expression in the small intestine of piglets. In addition, fermentation changed the structure of the CGW protein by degrading tightly folded structures into looser structures, leading to better digestion and absorbtion in the small intestine. Briefly, this novel fermentation technology is an effective method for increasing the nutritional value of CGM as a food ingredient.