DG, as a multifunctional additive, is generally protected as a trade secret by the world's major manufacturers, except for the related patents applied by Kao of Japan and Archer Daniels Midland of the United States, and there are few reports at home and abroad. Japan leads the world in DG preparation research. In recent years, domestic research and development have been carried out on the production of DG by enzymatic method, and the related patents of DG have been applied, but there is no report on the industrialization of DG in China at present.
In the early days, DG was produced by chemical method, but the reaction specificity was poor and the reaction steps were complicated, which required a lot of chemical reagents or organic solvents. The synthesis of DG catalyzed by lipase meets the requirements of clean production and green production. The industrial production of DG needs to adopt a continuous and efficient production mode. Among them, the most important factors mainly include three aspects:
(1) The choice of immobilized lipase is the key factor to determine the production efficiency of DG. Immobilized lipase can be reused, reducing the cost of lipase; The enzyme concentration in the reaction system is high, the reaction speed is fast and the period is short; The specificity of the enzyme is strong, the side effect is small, and the purification cost is reduced.
(2) Immobilized enzyme reactor: In order to realize the industrial production of DG, intermittent stirring reactor is not suitable, because the immobilized enzyme can not be loaded into this reactor at high density, and the shear force generated by stirring is easy to denature and inactivate the enzyme protein shedding carrier. Packed bed (fixed bed) reactor is suitable for long-term continuous industrial operation and can realize the maximum utilization of immobilized enzyme.
(3) Separation and extraction methods: There are four reported purification methods of glyceride: solvent crystallization separation, column chromatography separation, supercritical CO2 extraction and molecular distillation. Through analysis and comparison, molecular distillation can provide an efficient purification method for the industrial production of DG.
As a natural component of oil, diglyceride is also an intermediate product of oil metabolism. It has the advantages of safety, nutrition, good processability and high human compatibility. It is a multifunctional additive and has been widely used in food, medicine, chemical industry (cosmetics) and other industries. Recently, the diglyceride oil with nutrition and health care function made from ordinary oil has become one of the main directions of oil development and the focus of development by major oil companies, and the relevant departments in China have been fighting for it.