Enzymatic hydrolysis of proteins from yellowfin tuna (Thunnus albacares) wastes using Alcalase

Enzymatic hydrolysis of tuna stomach proteins by Alcalase was investigated in a batch reactor. The influence of the process variables (enzyme/substrate ratio; effect of intermediate substrate and enzyme addition) was studied with regards to the extent of proteolytic degradation and to the molecular weight distribution of the peptides. A linear correlation was found between the degree of hydrolysis (DH) and the enzyme concentration. After addition of extra substrate during the course of hydrolysis, the final DH obtained was proportional to the substrate added, suggesting that the concentration of hydrolysable bonds was one of the main factors controlling the hydrolysis rate. Preliminary results showed that tuna protein hydrolysates performed effectively as nitrogenous source in microbial growth media.