ABSTRACT

Fish protein hydrolysates were obtained from cultured rainbow trout (Oncorhynchus mykiss)
viscera using commercial and endogenous enzymes. Two methods were employed for hydrolysis:
acid autolysis (also known as silage) at room temperature for 10 days in acidic conditions, until
total solubilisation, and enzymatic hydrolysis using Alcalase 2.4 LFG, Protana Prime, and the
endogenous enzymes in the viscera. The effectiveness of both methods in releasing free amino
acids (FAA) was assessed. After evaluating the results, the most effective enzymatic hydrolysis
was optimized. The findings indicated that enzymatic hydrolysis with Alcalase, Protana Prime
and endogenous enzymes combined for 7 h at a dose of 1% of protein, and a 7-day acid autolysis
yielded the highest degree of hydrolysis (83.8% and 75.8%), a yield of FAA from viscera of 5.9%
and 3.2%, and a yield of FAA from total protein of 71.3% and 52.5%, respectively. In conclusion,
the use of commercial enzymes was more efficient in releasing amino acids, but endogenous
enzymes showed a strong proteolytic capacity during acid autolysis, suggesting it also as a
promising method to produce FAA-rich hydrolysates.