Abstract
Fishery processing industry produces a high number of by-products. Fortunately, some fish by-products can be reused and converted into valuable products, such as fish protein hydrolysates. Fish protein hydrolysate (FPH) is known to have a high functional value. This study aims to valorize the mackerel (Scomber japonicus) heads into FPH with biofunctional properties under different pH and hydrolysis duration. Hydrolysis was carried out at pH 0, 5, 7, and 9 for 12 and 24 hour. Response surface methodology was performed to determine the optimum production condition. The results showed that pH and hydrolysis duration had significant effects (p < 0.05) on yield, antioxidant activity, protein content, and degree of hydrolysis of mackerel FPH. The highest yield (59.89 ± 0.08%), with a protein content of 67.95 ± 0.49%, was obtained at pH 5 after 12 hour incubation. In addition, the mackerel fish protein hydrolysate had high antioxidant activity (36.95 ± 0.82%) with a degree of hydrolysis of 32.63 ± 1.12%. It was suggested that mackerel heads could be a potential resource to produce bio-functional fish protein hydrolysate. Further research on other properties of mackerel FPH and the use of different enzymes to produce better quality mackerel head FPH is recommended.