Characterisation and partial purification of proteolytic enzymes from sardine by-products to obtain concentrated hydrolysates

A procedure to recover proteases and lipases from the by-products of Monterey sardine (Sardinops sagax caerulea) has been developed, comprising 2 steps: a centrifugation at low temperature to eliminate more than 90% of the initial fat content, and an acetone precipitation step. After this treatment, enzymatic activity increased by 33.8% for lipase, 15.5% for trypsin, 14.8% for chymotrypsin, 93.4% for aminopeptidase, and 19.7% for pepsin. The extents of hydrolysis of fish by-product proteins by endogenous enzyme by-product extract, viscera concentrate extract, and commercial Alcalase (R) were 62%, 85%. and 28%, respectively. The two extract preparations from sardine by-product (viscera and by-product concentrate extracts) produced 3-fold greater hydrolysis than with the commercial enzyme. The recovery of enzyme concentrates from sardine waste has both ecological and economical advantages for the fish industry. (C) 2012 Elsevier Ltd. All rights reserved.