Coupling of ultrafiltration and enzymatic hydrolysis aiming at valorizing shrimp wastewater

• Wastewater generated during shrimp cooking was concentrated by ultrafiltration.
• The concentrated effluent was enzymatically hydrolyzed at different conditions.
• Protein content increased 3.2 times after ultrafiltration.
• Enzymatic hydrolysis was mainly affected by temperature and pH.
• Hydrolysates showed antioxidant capacity and suitable amount of essential amino acids.

The objective of this work was to obtain a protein hydrolysate from the wastewater generated during shrimp cooking, by coupling ultrafiltration and enzymatic hydrolysis processes. Initially, the effluent was concentrated by ultrafiltration, reaching a protein concentration factor of 3.2. The concentrated effluent was then enzymatically hydrolyzed, aiming at obtaining peptides with antioxidant capacity. The effects of some process variables – temperature (55–75 °C), pH (7–9) and enzyme/substrate (E/S) ratio (0.1–2.5%) – on the degree of hydrolysis and the antioxidant capacity were evaluated. The increase in temperature and pH resulted in lower degree of hydrolysis and higher antioxidant capacity. The conditions selected as the most suitable were: temperature of 75 °C, pH of 9.0 and E/S ratio of 0.1%. The hydrolysates produced at these conditions were also evaluated for total amino acid content and electrophoretic profile, showing a suitable amount of essential amino acids that covers the recommended daily needs.