Antioxidant and Anti-hypertensive Bioactive Peptides from Indian Mackerel Fish Waste

India ranks second in the harvesting and production of fish. The discard of fish is near about 20–40% of total fish weight. Therefore, a huge amount of fish waste is being generated, leading to the need for its better utilization. Protein hydrolysates from Indian mackerel fish waste were made by extracting protein using alkali and hydrolyzing them with the alcalase enzyme. For protein extraction and hydrolysis processes, factors such as temperature, stirring speed, pH, time, solvent load, and enzyme concentrations were optimized using empirical equations with response surface methodology. A protein yield of 75% was recorded to be the highest at a solvent load of 64%, at 490 rpm stirring speed, and for a time duration of 80 min. Alcalase enzyme showed the highest degree of hydrolysis, i.e., 71.72%, at an enzyme to substrate concentration of 40 U/mL, at 50 °C with pH 7.7 for 40 min. Fish waste protein hydrolysates having a high antioxidant and anti-hypertensive activity were successfully prepared from the waste.