Enzymic hydrolysis was applied for the efficient recovery of the protein sources from the fish processing by-product, cod frame. The enzyme used for the hydrolysis was crude proteinase extracted from tuna pyloric caeca. The resultant hydrolysate, cod frame protein hydrolysate (CFPH), was separated based on the molecular weight of the peptides in the hydrolysate and several functional properties were examined, including physicochemical properties (emulsifying and foaming property) and bioactivities (antioxidative and angiotensin I converting enzyme (ACE) inhibitory activity) to determine its potential functions. CFPH was processed through a series of ultrafiltration (UF) membranes with molecular weight cut-off(MWCO) of 30, 10, 5 and 3 kDA, and four types of permeates including 30-K (permeate from 30 kDA), 10-K (permeate from 10 kDA), 5-K (permeate from 5 kDA) and 3-K hydrolysate (permeate from 3 kDA) were obtained. 10- and 30-K hydrolysates showed excellent emulsion properties and whippability. The 10-K hydrolysate showed high antioxidative activity, while the 3-K hydrolysate had excellent ACE inhibitory activity. In terms of all functional properties tested, the fractionated hydrolysates were superior to the original non-separated hydrolysate. These results suggested that separating hydrolysate enhanced several functional properties. (C) 2000 Elsevier Science Ltd. All rights reserved.