Lipase (EC 3.1.1.3), the full name of triacylglycerol hydrolase, is a class of biological enzymes that can hydrolyze long-chain fatty acid glycerides into fatty acids and monoglycerides, diglycerides or glycerol. It can be derived from animals, plants and microorganisms, and can catalyze reaction types such as hydrolysis, esterification, and transesterification. The reaction has the advantages of mild conditions, low energy consumption, low raw material requirements, and high quality of finished products. It can be used in food, medicine, biodiesel and other fields and has huge application potential. Although lipases are widely used in industry, most of them have short lifespan, and free enzymes are not dissolved in the organic phase, and are easy to agglomerate during the reaction process, which greatly reduces the availability of enzymes and makes enzyme recovery rates low. Using immobilization technology to immobilize the enzyme on an inert carrier can improve the solubility of the enzyme in the organic phase, and increase the utilization rate and recovery rate. This is conducive to continuous and low-cost production, so the industrialization of lipase catalytic technology largely depends on enzyme immobilization.
Immobilized enzyme technology is a type of technology that uses solid materials to confine or confine the enzyme to a certain area, but still has catalytic activity, and can be recycled and reused. Using immobilization technology to immobilize lipase on an inert carrier can improve its diffusion effect and thermal stability in the organic phase, and at the same time facilitate the recovery, continuous and low-cost production of the enzyme. So far, the methods used to immobilize enzymes mainly include embedding method, adsorption method, covalent binding method and cross-linking method. In terms of carriers, carriers with different forms and functions are used to immobilize enzymes, including natural polymer materials, inorganic materials, synthetic polymer materials, and new carrier materials with specific functions.
Application of immobilized lipase in food industry
Synthesis of sugar esters
Sugar esters are a class of nonionic biosurfactants that take sugar groups as hydrophilic groups and fatty acids as hydrophobic groups, and have both hydrophilicity and lipophilicity. Sugar ester food additives have the advantages of excellent surface activity, biodegradability, odorless, and non-irritating. Certain sugar esters also have antibacterial and antiviral activities, and are now widely used in the food industry as food emulsifiers, texture modifiers, and fresh-keeping fungicides.
Grease modification
Fat modification is an important part of food processing. Changing the physical and chemical properties of oils and developing oils with higher nutritional value has great value and market potential. Lipase has position specificity and fatty acid specificity, and can be used as a biocatalyst for lipid modification by catalyzing transesterification, transesterification, hydrolysis and other reactions. Therefore, it is widely used in the oil industry.
Synthesis of aromatic ester compounds, aromatic compound esters
The compound is composed of short-chain fatty acids and alcohol compounds. It is the main component of flavor and fragrance. It has a wide range of applications in the pharmaceutical, cosmetic and food industries, such as butyl butyrate, isoamyl acetate and other aromatic lipid compounds. It is commonly used in the food industry to regulate food flavor.
Although the immobilized enzyme technology can improve the properties of lipase to a certain extent, it cannot transform the lipase in nature. At the molecular level, rational or irrational design is an important method to improve the properties of lipases according to the degree of understanding of the relationship between enzyme structure and function. Rational design and semi-rational design are the main directions for lipase modification at the molecular level in the future. In summary, improving the performance of lipase through these design ideas and expanding its application in the food field will have great research prospects.