Optimization of Protein Recovery During Hydrolysis of Yellowfin Tuna (Thunnus albacares) Visceral Proteins

Abstract

Protein hydrolysates were prepared from yellowfin tuna viscera using Alcalase®. Response surface methodology (RSM) was applied to study the effect of independent variables, enzyme activity, temperature, and time on the protein recovery (PR) as the response. The coefficient of determination (r² = 98%) was satisfactory, and the lack of fit test showed a non-significant value for the PR model equation, indicating that the regression equation was adequate for predicting the PR under tested combinations of values. Enzyme activity at 79.9 AU/kg protein, temperature at 59.9°C, and the time of 105 min were found to be the optimum conditions to reach the highest PR (85%). Considerable soluble protein was released with increasing degree of hydrolysis (DH). The yellowfin tuna visceral hydrolysates' amino acids profiles showed high essential amino acids content, although lysine, methionine, and phenylalanine were limited. In addition, the results showed that with increasing hydrolysis time, the amino acids increased. Yellowfin tuna visceral hydrolysates were rich in flavor amino acids which can be used as a taste enhancer.

Keywords:

• fish protein hydrolysates
• tuna viscera
• protein recovery
• amino acid profile
• Alcalase®

Acknowledgments

This study was funded by Tarbiat Modares University, Iran. The authors would like to thank Professor Turid Rustad at NTNU, Trondheim, Norway, for scientific and technical support.