Enzymatic recovery of cod frame proteins with crude proteinase from tuna pyloric caeca

To recover efficiently proteins from fish frame that is remained on bone portions after filleting fish in fish processing manufactory, the enzymatic recovery by hydrolysis was applied. The enzyme was a crude proteinase partially purified from tuna Thunnus thynnus pyloric caeca. Tuna pyloric caeca crude proteinase (TPCCP) showed the highest hydrolytic activity for BAEE (N-benzoyl-L-arginine ethyl ester), synthetic substrate of trypsin. The optimum activity condition of TPCCP for fish (cod; Gadus macrocephalus) frame proteins, the deboned proteins isolated from fish frame, was known as pH 10 at 45-50 degrees C. The hydrolysis reaction for cod frame by TPCCP was attained to an end after 12 h incubation in the above condition. Under the optimum reaction conditions for the same enzyme concentration, the degree of hydrolysis by TPCCP on time course was similar to those by purified proteinases such as chymotrpysin, pronase E, papain, etc. After the cod frame was treated with TPCCP for 12 h at 50 degrees C, all tissues, mainly muscle proteins, were readily digested from fish bone and approximately 80% of the total soluble protein was hydrolyzed. Therefore, it appeared that the protein from fish frame as fish processing waste could be efficiently recovered with TPCCP.