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Abstract

Fish protein hydrolysate, which is released to the environment as tuna processing waste during the hydrolysis reaction of Sarda orientalis’ black muscle, could be used as a nutritional source of nitrogen for food products because of its valuable properties in antioxidant effects. This study used Protamex protease (endopeptidase) to hydrolyze the tuna’s black muscle (TBM) and to produce fish protein hydrolysate (FPH) for producing nutritional food powder. To access the FPH production, optimized conditions of reaction in hydrolyzing TBM were determined by factorial experimental design with the Box–Behnken model at a ratio of 0.45% enzyme/substrate, 100% added water content and temperature of 56 °C for 4.0 h. Consequently, the FPH obtained with the optimized condition resulted in an average degree of hydrolysis of 7.72% in response to the required range of 5–20%. Moreover, this FPH was detected for compositions of amino acids and peptides with low molecular weight less than 14 kDa and was tested in high antioxidant activity of 70% at its concentration of 500 µg mL−1. This study has provided an efficient procedure to solve the solid waste of TBM from the seafood manufacturing factories and transformed it into valuable products in the food industry.