Extracted pepsin of trout waste and ultrasound-promoted method for green recovery of fish collagen

Abstract

Collagen type I is a prominent protein in animal tissues. This structural protein can be commercially derived from fish processing waste without any health risk. The current study aimed to investigate the efficacy of rainbow trout pepsin and the ultrasound-promoted method on collagen recovery. Pepsin extract was purified from rainbow trout stomach in order to use in collagen extraction from wasted yellowfin skin through ultrasound technique in five durations (0, 5, 10, 15, and 20 min). The 15 min ultrasound treated pepsin soluble collagen indicated the highest recovery yield (23.8%) as well as the highest imino acid content (18.2%). The structure of type I collagen was observed in the SDS-PAGE pattern of collagens and no structural change occurred during the extraction process. The presence of the helical structure in collagen samples was confirmed by UV and FTIR spectra. The ultrasound cavitation advanced the viscosity of collagens and resulted in excellent solubility in acidic environments and lower salt concentrations. Ultrasound-treated samples suggested superior water holding capacity along with emulsifying, and foam attributes. The improved gel strength of collagens was parallel with increasing the time of ultrasound up to 15 min. Free radicals scavenging ability and ferric reducing power of collagens were positively stimulated by increasing the time of the ultrasound up to 15 min. Therefore, this study contributes to the development of green technology and the promotion of by-product utilization for collagen recovery as a potential practical protein in biomaterial, wound dressing, drug delivery, food, and cosmetics products.