Optimization Production of Hydrolyzed Protein of Fish from Milkfish Scales Enzymatically Using Response Surface Methodology (RSM)

This study optimized HPF production from milkfish scales via enzymatic hydrolysis using commercial papain, employing Response Surface Methodology (RSM) with the Box-Behnken model. The three factors were enzyme concentration (0.23, 0.31, and 0.38 U), incubation temperature (40, 60, and 80 °C), and incubation time (1, 3, and 5 h). The predicted optimal condition was 0.31 U of papain at 60 °C for 3 h, yielding 13.40% HPF. Under this condition, HPF solubility was 89.25 ± 2.45%, and soluble protein content was 0.30 ± 0.01 mg/mL. Cadmium content was 0.07 mg/kg, whereas lead content was 0.89 mg/kg. Antioxidant inhibition reached 25.25 ± 0.41% at 5,000 ppm and 40.19 ± 1.78% inhibition at 10,000 ppm, equivalent to 0.23 and 0.36 mM Trolox, respectively.