Optimization of the Enzymatic Hydrolysis of Yellowfin tuna, (Thunnus albacares) Viscera by Response Surface Methodology

Abstract

Tuna is abundant in the Philippines, but the by-products during processing in various forms may be a source of waste and environmental pollution. To minimize these wastes, they are utilized directly or fermented to serve as food for humans and animals and as a functional food ingredient since they are rich in proteins and polyunsaturated lipids. For this purpose, they are often converted into protein hydrolysates using proteolytic enzymes. This study optimized the hydrolysis of the yellowfin tuna (Thunnus albacares) viscera (YFTV) using the enzyme neutrase to produce hydrolysates with a high degree of hydrolysis (DH) and foaming capacity (FC). Using the central composite design of the Response Surface Methodology (RSM), the YFTV protein hydrolysis at varying concentrations (0.5-1.5%, w/v) and hydrolysis time (60 to 180 min) was carried out. From the RSM-generated model, the optimum conditions to obtain the highest DH was 179.50 min hydrolysis time and 1.5% enzyme concentration, and for the highest FC, 176.58 hydrolysis time and 1.5% enzyme concentration. The predicted optimum values using the generated linear and quadratic equations were 17.26% DH and 1.60% FC. The lack of a fit test for both responses yielded an insignificant value (p > 0.05) for the model, suggesting that the regression coefficient was sufficient for estimating both responses under any group of variables. The optimized protein hydrolysis conditions of YFTV using Neutrase could be applied in food production systems, especially downstream processing. Furthermore, the utilization of tuna viscera as protein hydrolysates could potentially contribute to the waste management of these processing by-products.