Characterization of green mussel (Perna viridis) hydrolysate prepared using alcalase and starfruit (Averrhoa carambola. L) protease

This study was carried out to evaluate the efficiency of natural protease extracted from starfruit (Averrhoa carambola. L) to hydrolyse green mussel (Perna viridis). Starfruit juice from fruit of maturity index 2 was extracted and purified using acetone precipitation method. The obtained protease was then used to hydrolyse green mussel and compared with alcalase. The conditions used to produce starfruit protease hydrolysate (SPH) were pH 8, E/S 3%, 60°C for 2 hrs and alcalase hydrolysate (AH) were pH 9, E/S 3%, 60°C for 2 hrs. Yield, degree of hydrolysis (DH), protein concentration, color, solubility, heat stability and molecular weight distribution of the hydrolysates were determined. Results showed that the acetone precipitated protease had higher specific activity (0.31 U/mg) than the crude extract (0.16 U/mg). Alcalase exhibited higher DH (34.82%) than starfruit protease (11.68%), higher yield and protein concentration. The soluble protein content of both hydrolysates were high in pH range of 3 to 10 while AH was more stable at high temperature. The SDS-PAGE profiles of the hydrolysate showed that AH contains molecular weight (MW) lower (<10 kDa) than SPH (<50 kDa), thus it corresponds with the characteristic of AH that was more soluble (91.51%) as compared to SPH (81.21%). It is concluded that hydrolysis using alcalase produced better results in terms of yield, DH, protein concentration and molecular weight distribution. However, in terms of solubility and heat stability both hydrolysates showed high soluble protein content. Thus, starfruit protease has the potential to be used as an alternative source of protease for the production of protein hydrolysate.