Recovery of digestive enzymes from Atlantic cod (Gadus morhua) and their utilization in food processing

• Main Author: Han, Xiao-Qing, 1955-
• Other Authors: Memorial University of Newfoundland. Dept. of Biochemistry
• Format: Thesis
• Language: English
• Published: 1993
• Subjects: Atlantic cod; Digestive enzymes; Fishery processing; atlantic cod; Gadus morhua; Newfoundland studies; University of Newfoundland
• Online Access: http://collections.mun.ca/cdm/ref/collection/theses2/id/227258

Thesis (M.Sc.)--Memorial University of Newfoundland, 1994. Biochemistry Bibliography: leaves 120-135. An extraction process for the recovery of proteolytic enzymes from the digestive tract of cod (Gadus morha) is described. Processing variables were optimized by employing a rotatable experimental design with computer graphics-assisted response surface methodology (RSM). A simple extraction procedure was developed which effectively isolated both acid and alkaline proteases from cod viscera with recovery yields of 52% and 30%, respectively. Further purification and characterization revealed that the crude acid proteases consisted of three types of gastric enzymes designated as acid proteases A, B, and C. Acid protease B was classified as fish pepsin II. Acid proteases A and C possessed properties similar to chymosin and gastricsin, respectively. The partially purified alkaline proteases possessed properties of trypsin-like enzymes and acted on N-benzoyl-L-tyrosine ethyl ester (BTEE), a synthetic substrate for chymotrypsin. -- Utilization of the crude isolated proteases was tested in milk-clotting for cheese making, as well as preparation of protein hydrolysates from under-utilized fish species. Cod pepsin was capable of clotting milk efficiently at low temperatures, which shows its potential use in cold renneting of milk. Capelin protein hydrolysate with a recovery yield of 55.8% was obtained when crude cod gastric proteases were used over a 4 h hydrolysis period at ambient temperatures.