Continuous production of high degree casein hydrolysates by immobilized proteases in column reactor

The enzymatic complete hydrolysis of casein was investigated by using immobilized endopeptidase and exopeptidase packed in the jacketed column reactors. The mass transfer efficiency of proteins was improved by using sliced shrimp chitin hull as enzyme support, which formed a network structure inside the column reactor that prevented the formation of protein precipitate and increased the line flow rate of protein solution. The specificity of the protease was of crucial importance for both the hydrolysis degree and the free amino acid content of the hydrolysates. Of the enzymes, tested, the immobilized A. oryzae protease was the most effective enzyme in breaking down the casein molecules and releasing the free amino acid from casein hydrolysates. The immobilized pancreatic and kidney exopeptidase could lead to a 20% increase of free amino acids. The free amino acid content of casein hydrolysates was 34.81% after processing and could reach to 64% if the column length was doubled, but 100% hydrolysis was impossible as the reverse reaction was also taking place. The casein hydrolysates was characterized by its high degree of hydrolysis and high content of free amino acids. It can be applied in infant formula, element diet, and as a protein ingredient for food industry.