Extraction Hydrolysates from Larimichthys Polyactis Swim Bladder Using Enzymatic Hydrolysis

Abstract

As a kind of biopolymer, hydrolysates of fish swim bladder, safer than those of land mammals, are widely used in food, cosmetics as well as pharmaceutical and biomedical fields for their biocompatibility, biodegradability, and weak antigenicity. To enhance hydrolysate production, in this paper, the papain and alcalase hydrolysis processes of larimichthys polyactis swim bladder were optimized with orthogonal experiments. With 89.5% hydrolysate yield, the optimal processing conditions for alcalase were solid-liquid ratio of 1:30, enzyme concentration of 0.7%, and extraction time of 6 h. As for papain, under the optimal processing conditions: solid-liquid ratio of 1:20, enzyme concentration of 0.5%, and extraction time of 8 h, the hydrolysate yield was 65.1%. To obtain higher hydrolysate yields, the ultrasonic pretreatments were implemented before the optimal enzyme hydrolysis processes. With ultrasonic waves of 100 W for 50 min, the hydrolysate yields were increased 2.1% (alcalase) and 4.5% (papain), respectively. The Fourier Transform Infrared (FTIR) spectroscopic analysis revealed that the hydrolysates extracted by papain exist in triple-helical forms. The Ultra-Violet (UV) absorption spectra indicated that the aromatic amino acids in the hydrolysates had strong absorptions in the wavelength range of 240 nm–300 nm. The results of this research demonstrate that the alcalase hydrolysates have better solubility in water and the solution is more stable under ambient temperature. However, the hydrolysates extracted by papain have a gel property and are insoluble in weak acid at room temperature, which is more suitable for applications in feedstock of biomedical.