Valorizing fish processing waste: Production of protein hydrolysates from milkfish (Chanos chanos) by-products using acid hydrolysis

Milkfish (Chanos chanos) by-products were used as raw material for the production of protein hydrolysates. Acid hydrolysis was performed at 121 °C for 90 min at 15 psi using various concentrations of hydrochloric acid (4, 6, and 8M). The protein hydrolysates were characterized for the degree of hydrolysis (DH), and antioxidant and other functional food properties. The yield obtained ranged from 5.14±0.42% to 6.08±1.53%. High DH was observed at a high acid concentration with 43.88±9.50% DH for 8M HCl. Regarding the functional food properties, solubility of over 80% over a wide range of pH (2-12) was observed, and emulsifying and foaming properties were found to depend on the pH (2-10). As for the antioxidant activity, 8M exhibited the highest antioxidant activity among the three treatments. The results showed that milkfish by-products have potential to serve as raw material for protein hydrolysates that can be used as ingredients for food formulations.