Abstract: In the present study, limited hydrolysis of protein isolate from blue round scads was performed with alcalase. The effects of the degree of hydrolysis (DH) on the solubility, oil-holding capacity and functional properties including emulsifying and foaming properties of hydrolysates were investigated. The results showed that the molecular masses of the proteins were remarkably decreased by alcalase hydrolysis. The solubility of the proteins was significantly improved and increased as DH increased. The emulsifying and foaming properties of the proteins significantly increased after hydrolysis, showing a trend of increased first and then decreased with increasing DH. At pH 4.0, the worst emulsifying and foaming properties were recorded for the hydrolysates at different DHs. The hydrolysate with 5% DH had the highest emulsifying capacity ((100.9 ± 0.7) m2/g) and highest foaming capacity ((227.3 ± 3.8)%) at pH 10.0 and 7.0, respectively. All hydrolysates except 20% DH showed a notable increase in oil-holding capacity, with the highest value of 3.50 g/g (oil/protein) being found at 5% DH. In conclusion, a certain degree of hydrolysis could remarkably improve the functional properties of protein isolate from blue round scads. The present work provides a theoretical reference for application of fish protein isolate as a protein ingredient in foods.

Key words: blue round scads; protein isolate; limited hydrolysis; functional properties