Optimizing the Hydrolyzed Protein Process from Metapenaeus Affinis Shrimp Wastes

Every year, the fisheries industry produces approximately 106 tons of wastes, most of which are processed, wasted low-value products such as animal feeds or discarded. Crustaceans include significant quantities of polysaccharides in their skins, which can be used in various food industries. This study was carried out to optimize production of hydrolyzed proteins from the skin and head of Metapenaeus affinis using response surface method (RSM) and papain enzyme.

Investigated factors to reach the maximum degrees of hydrolysis included various temperatures (35, 65 and 95 °C), times (45, 55 and 65 min) and enzyme/substrate ratios (1.5, 2.25 and 3%). Hydrolysis conditions that showed the best degrees of hydrolysis were optimized using RSM with central composite design (CCD).

Results showed that effects of reaction variables on each of the test responses were significant (p < 0.05). Based on the three-dimensional graphs of the response surface analysis, the optimal operating conditions for the maximum degree of hydrolysis of the shrimp head protein were achieved using the rate of 74.44%, time of 95 min, temperature of 61.51 °C and enzyme concentration of 2.23%. Moreover, the optimal conditions for the maximum degree of hydrolysis of the shrimp shell proteins included 74.53%, 75.30 min, 56.39 °C and enzyme concentration of 2.99%.

This study showed that shell and head of M. affinis included high hydrolyzed proteins that could be useful for medicinal and human uses.