Towards Zero-waste Recovery of Bioactive Compounds from Catfish (Pangasius hypophthalmus) By-products Using an Enzymatic Method

Abstract

Catfish (Pangasius hypophthalmus) is one of the main seafood products of Vietnam with a large amount of over 1.3 million tons in 2018. However, after the processing, large amount of the harvested catfish is considered as by-products. In this study, catfish by-products have been used to produce three bioactive components, including fish protein hydrolysate (FPH), hydroxyapatite (HA) and lipid fraction by an enzymatic method. The fish by-products were hydrolyzed by using an Alcalase-substrate ratio of 0.4% (v/w) at 60 °C and natural pH for 9 h with a water-raw material ratio of 1:1 (mL/g). The results show that the protein hydrolysate has degree of hydrolysis (DH) of over 30%, nitrogen recovery (NR) of over 80% and contained a large amount of essential amino acids. HA particles have a size of 50–70 nm with high porosity and quite uniformity, suggesting its potential applications such as bone scaffold or regenerative materials. The lipid fraction has high vitamin A content with a small amount of fatty acids (ca. 90 mg/g) that can be refined for further food applications. This recovery method is simple, environmentally-friendly and can be scale-up easily. In addition, the cheap fish by-products were processed to give value-added products as well as reduce the undesirable environmental impact.