Applications of oxidases in modification of food molecules and colloidal systems: Laccase, peroxidase and tyrosinase

Improving the quality attributes and nutritional profiles of functional foods has been a major focus of research in recent years. Enzymatic modification of food molecules can be used to enhance their functional performance in foods. Laccase, peroxidase, and tyrosinase can catalyze the oxidation of proteins, polysaccharides, and polyphenols, and have great application potential in the construction of food colloids. This review summarizes and compares the catalytic mechanisms of laccase, peroxidase, and tyrosinase for the modification of food molecules and their applications in colloidal systems, as well as highlighting the advantages of combining different oxidases. Laccase, peroxidase and tyrosinase catalyze the oxidation of food molecules in two steps. The first step involves an enzymatic reaction to generate free radicals or quinones; the second step involves a non-enzymatic reaction of free radicals or quinones with other molecules. Enzymes mainly play a role in initiating reactions in the whole process, which generally requires the participation of phenolic substances. In addition, polysaccharides and proteins containing phenolic groups can also be directly cross-linked. Peroxidase seems to have the most extensive catalytic substrates among the three oxidases reviewed. The cross-linking of food molecules induced by these oxidases helps to improve the formation and stability of colloidal systems, such as emulsions, nanoparticles, and microgels, thereby enhancing their potential for encapsulating, protecting, and delivering bioactive compounds. Employing a combination of different oxidases in food colloids can overcome the limitations of single oxidase and improve the functionality of the overall system.