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268 PROCEEDINGS OF INTERNATIONAL SCIENTIFIC CONFERENCE ON APPLIED BIOTECHNOLOGYexpression. Finally, taste identification was carried out. The results showed that increasing the number of tandem copies of a single peptide did not enhance the umami effect [21]. After that, a research team conducted an experiment on the tandem of multiple peptides. In the experiment of the construction and expression of tandem genes of three flavoring peptides, they copied and cloned the tandem unit genes of the three umami peptides into the pET30a expression vector, introduced it into the host bacterium BL21 (DE3), and successfully expressed it. The experimental results showed that the tandem of multiple peptides increased the variety and quantity of umami substances, achieving the effect of enhancing umami taste [22].5. PRODUCTION OF UMAMI PEPTIDEThe production methods of umami peptide are diverse. Currently, the main method is enzymolysis [1, 23, 24]. The enzymolysis method mainly involves obtaining umami peptide by hydrolyzing proteins with proteases. Or it uses microorganisms to couple the fermentation of proteases and the enzymolysis process of proteins to obtain umami peptide. The reaction conditions of the enzymolysis method are mild and easy to control, and the production process is simple. However, this method has many by-products, low yield, and poor overall benefit. It is also prone to produce bitter peptides during the production process, which affects the taste of umami peptide. Therefore, people have begun to pay attention to a new synthesis path of umami peptide - the bioengineering method.The bioengineering synthesis method involves introducing the DNA fragment containing the target gene into the recipient cell via a vector or inserting the foreign gene into the phage genetic sequence for expression. Then, it is processed and purified to obtain the target active peptide. This method has