Utilization of Tuna Processing Byproducts: Protein Hydrolysate from Skipjack Tuna (Katsuwonus pelamis ) Viscera

Abstract

Alcalase showed optimum activity against skipjack tuna (Katsuwonus pelamis) viscera at pH 10 and 65C. Enzyme concentration, reaction time and fish viscera/buffer ratio affected the degree of hydrolysis (DH) (P < 0.05). Hydrolysis with an enzyme level of 3% (w/w) for 20 min with fish viscera/buffer ratio of 1:2 (w/v) was found to be the optimum condition. Protein, lipid and ash content of freeze-dried hydrolysate were 81.04, 6.78 and 12.01% dry weight basis, respectively. It was brownish yellow in color (L* = 62.46, a* = 1.44 and b* = 23.05). The hydrolysate contained a high amount of essential amino acids (43.13%) and had glutamic acid, methionine and aspartic acid as the dominant amino acids. Therefore, protein hydrolysate derived from skipjack tuna viscera could potentially serve as a good source of peptides and amino acids and the production of tuna waste protein hydrolysate has both ecological and economical advantage for the tuna industry. Practical Applications Efficient utilization of fish byproducts, especially viscera, is important for the economic viability of the aquatic food industry. Enzymatic hydrolysis is one of the most effective technologies for recovering value-added proteins from fish viscera without losing their nutritional value. In this study, protein hydrolysate prepared from skipjack tuna viscera using Alcalase showed high protein content. Hence, it can be used in a wide range of food additives, diet nutrients and pharmaceutical agents.