Transglutaminase catalyzed amination of food protein and peptides with biogenic amines: studies on functionality and antioxidant activity

Abstract

There is a growing demand for innovative and affordable technologies in the food industry to modify ingredient functionality and to ensure product safety. Proteins are essential components in many food systems, and their structure can be modified in a variety of ways to control and improve functional characteristics of a food system. The enzymatic modification of proteins with transglutaminase is one such novel technology that has a broad range of applications, and was the focus of this research. In the first study of this research, hydrolyzed pea protein were modified by microbial transglutaminase (MTGase) from the Streptomyces mobaraensis species. Biologically active (biogenic) amines histamine and tyramine were used as amine donor substrates in this enzyme-catalyzed reaction. Conjugation of biogenic amines and pea protein hydrolysates was achieved in the presence of MTGase after 6 h of incubation at 37°C. Conjugation progress was monitored by high performance liquid chromatography and fluorescence spectroscopy. Seventy six percent of histamine was covalently incorporated to protein hydrolysates by MTGase, thereby reduced the concentration of undesirable biogenic amine. Also, the MTGase-catalyzed introduction of tyramine into pea protein hydrolysates substantially improved the antioxidant potential of the newly formed conjugates. In the second study, porcine skin gelatin was modified by MTGase-induced amination with tyramine in an aqueous media at 50°C. Gelation and melting iii temperatures, viscoelastic behaviour, as well as gelation rate and gel strength of tyramine-gelatin conjugates and MTGase-cross-linked gelatin were determined. MTGase-catalyzed cross-linking increased the gelation and melting temperatures of the gel. Incorporation of tyramine via MTGase did not change the gelling and melting temperatures of the gelatin. Tyramine incorporation negatively affected the gelling behaviour of the gelatin and was likely due to covalent tyramine-gelatin bonds that interfered with the normal formation of triple helix networks. Overall, this research demonstrated biogenic amines, as potential substrates for MTGase, were able to introduce into food proteins and peptides. A combination of glutamine-containing peptides together with MTGase has the potential to decontaminate fermented foods and beverages for biogenic amines.