Simultaneous recovery of lipids and proteins by enzymatic hydrolysis of fish industry waste using different commercial proteases.

Four different commercial proteases (Protease-P-Amano6, Alcalase®, Protex 7L®, and Neutrase®) were evaluated for recovering lipids and protein simultaneously by hydrolysis. Fungal protease (Protease-P-Amano6) resulted in maximum lipid recovery (74.9%) followed by alcalase (61.7%). Peroxide value (PV; milli-equivalents of oxygen per kilogram) in the oil recovered after hydrolysis was 40.48 compared to 8.7 in lipids from fresh fish viscera. However, addition of tertiary butyl hydroxyl quinine at 200 ppm level maintained the PV of oil recovered by hydrolysis closer to oil from fresh waste. Degree of hydrolysis was the highest in case of fungal protease (49.1%) where neutrase resulted in higher total antioxidant activity (micrograms of ascorbic acid equivalents per milligram protein) of 34.4. Protein hydrolysate prepared using fungal protease had the higher diphenylpicrylhydrazyl radical scavenging activity as compared to those from other enzymes. The results indicate the utility of commercial proteases in providing an ecofriendly and feasible solution for reducing disposal problems associated with fish processing.