Production and characterization of fish protein hydrolysate: Effective utilization of trawl by-catch

Abstract

• Extraction of Fish Protein Hydrolysate (FPH), from discarded by-catch fishes. • Enzymes, namely pepsin and proteinase K, were used to prepare FPH1 and FPH2 • Functional properties like solubility, foaming and emulsifying properties, oil and water-binding capacity, are compared. • FPH 1 was found to have improved functional properties. • It offers the potential to be used for various applications in the food industry. This research was conducted to efficiently extract Fish Protein Hydrolysate (FPH) from Secutor insidiator using papain and proteinase K enzymes. The degree of hydrolysis was found to be 0.8 and 0.9 for proteinase and papain respectively. The proximate analysis of the prepared FPH indicated the levels of Moisture (5.95% and 4.86%), Protein (92.14% and 89.24%), Fat (0.6% and 1.02%) and Ash (6.23 and 4.79) for papain and proteinase respectively. High solubility index (75 – 80%) was observed for the pH levels of 2, 6, 7, 8 & 10 and low solubility index of 31.75% and 32.18% was observed at pH 4 for proteinase and papain respectively. The molecular weight of the hydrolysates was estimated using SDS-PAGE method. Both samples (FPH 1 and FPH 2 ) produced bands at a molecular weight of 15 kDa and the second bands lies in between 25 kDa and 75 kDa. The foaming properties were highest at pH 2 (80 – 85%) and lowest at pH 4 (10-20%). The water binding capacity was observed to be at the highest at 0.2% concentration and there was a gradual decrease from 0.4 to 1.0% concentration of FPH. The oil binding capacity was found to be high at concentrations 0.2 and 1.0% and emulsifying properties were observed to be at the maximum in pH 2 and 10. Among the two Fish Protein Hydrolysates (FPHs) prepared, FPH 1 (proteinase) has comparatively better improved functional properties than FPH 2 (papain).