A Novel Technological Process of Extracting l-Tyrosine with Low Fluorine Content from Defatted Antarctic Krill (Euphausia superba) By-product by Enzymatic Hydrolysis

Abstract

Antarctic krill (Euphausia superba) offers a high potential for development of innovative food products due to its large reserves and satisfied nutritional values. Defatted krill powder by-product generates from the process of krill oil, which is rich in various types of amino acids. This study aimed at recovering tyrosine from defatted krill by-product through enzymatic hydrolysis. Defatted krill by-product was hydrolyzed with three types of protease under optimum conditions with different incubation time. Free tyrosine dissociated from protein through hydrolysis by trypsin and was detected in the protein hydrolysates. Content of tyrosine increased with the increasing of incubation time till 5 h. Tyrosine extract contained 6.43 mg/kg fluorine and over 95 % of tyrosine, which demonstrated its high purity and safety. Tyrosine extract showed rod-shaped microstructure through scanning electron microscope analysis. Crystalline structure and thermal properties of tyrosine extract agreed well with those of l-tyrosine standard. During this process, both tyrosine of high purity and bioactive peptide products were obtained.