Bio‐functional properties of sardine protein hydrolysates obtained by brewer's spent yeast and commercial proteases

BACKGROUND The canned‐sardine industry generates large amounts of protein‐rich waste, which demands useful exploitation. This paper describes the potential use of muscle and viscera proteins from canned sardine by‐products as substrate to obtain hydrolysates with biological and functional properties. Three enzymatic approaches, brewer's spent yeast (Bsy) proteases, Alcalase® and Neutrase® were applied to perform protein hydrolysis at the same proteolytic activity (1 U mL −1 ), using an enzyme/substrate ratio of 20% (v/v), at 50°C and for 7 h. Hydrolysis degree (DH), antioxidant and angiotensin I‐converting enzyme inhibitory (ACE‐I) activities, functional properties (i.e. solubility, emulsifying and foaming properties, water and oil binding capacity) and colour were investigated. RESULTS All hydrolysates presented a high protein content [52.7–83.2% dry weight (DW)] and low fat content (0.9–3.9% DW). Alcalase® treatment of muscle and viscera proteins resulted in higher DH (7.5% and 8.6%, respectively) and higher biological activities ( P < 0.05). All hydrolysates had excellent solubility and presented functional properties. Among viscera hydrolysates, treatment with Bsy proteases promoted higher emulsion (80.1 m 2 g −1 ), foaming (79.2%) and oil binding capacity (5.8 g g −1 ) of viscera sardine proteins. CONCLUSION Improved biological and functional properties were observed for sardine protein hydrolysates produced using the three enzymatic treatments tested.