Optimization of enzymatic hydrolysis of boso fish (Oxyeleotris marmorata) protein based on the degree of hydrolysis and the physical properties of the resultant hydrolysates

Abstract

Fish protein hydrolysates (FPHs) were produced from boso fish (Oxyeleotris marmorata) through enzymatic hydrolysis using papain as the hydrolysis agent. Papain concentration (0.2–0.4%), temperature (45–55°C), and time (4–12 hrs) were chosen as the independent factors while the degree of hydrolysis (DH), viscosity, and turbidity of the resultant FPHs were recorded as the responses. This study aimed to optimize the enzymatic hydrolysis of boso fish protein using the Box-Behnken Response Surface Methodology (RSM) design. The optimum condition for the boso fish protein hydrolysis based on the DH was predicted at 0.2% of papain concentration, 55°C, and 12 hrs, which would give a DH of 18.63% and an R2 of 90.90%. The FPHs prepared with moderate hydrolysis conditions (0.3% of papain concentration at 50°C for 8 hrs) were spray-dried with the yield ranging from 5.37% to 16.70% (w/w). The spray-dried FPH displayed a globular structure with a diameter of 1–7 μm as observed under the scanning electron microscope (SEM). The total colour difference of the dried FPH was 10.15 compared to the standard white tile. The particle size analysis in distilled water exhibited some distinct peaks which were distributed within 200–1,100 nm with an intensity of 18.1%. This study showed the potential of boso fish for FPH production by using the papain enzyme.