The immobilized porcine pancreatic exopeptidases and its application in casein hydrolysates debittering.

The practical application of exopeptidase has been limited by the high cost of the enzymes resulting from the low content of individual exopeptidase in the raw material. This can be overcome by the use of a combination of all the exopeptidases in the same enzyme source, as well as the use of the enzyme immobilization technology. A porcine pancreatic exopeptidase mixture was prepared by the ammonium sulfate precipitation at 35% saturation of the autolyzed pancreatic juice. The enzyme preparation was immobilized on thin shrimp chitin film by crosslinking with glutaraldehyde. The immobilized porcine pancreatic exopeptidases (IPPE) was effective in releasing the free amino acids from peptides. Of these amino acids, the concentrations of arginine, lysine, histidine, tyrosine, phenylalanine, leucine, and glutamine were increased much more than those of other amino acids. This indicated that both the porcine pancreatic exopeptidases preparation and the IPPE contained carboxypeptidase A, B, and aminopeptidase. The IPPE was also efficient in the decrease of the hydrophobicity of protein hydrolysates demonstrated by hydrophobic chromatographic analysis. This led to the application of the immobilized exopeptidases in protein hydrolysate debittering. The IPPE was able to remove the bitterness of the tryptic/chymotryptic casein hydrolysates.