Lumping Kinetic Model For Casein Enzymatic Hydrolysis Reaction

Enzymatic hydrolysis of protein is a kind of biochemical process to yield small molecular products such as peptones and peptides. This thesis tried to study on the proteolysis process of casein-trypsin reaction system, using the lumping method, and established the common four lumps model for enzymatic hydrolysis of protein. The reaction rate constants were estimated by Marquardt method and the prediction ability of the kinetic model were tested. The content mainly included the followings.First, the changes of casein hydrolysis rate with the operating parameters were studied. And there are optimal temperature, pH, and optimal rate of substrate and enzyme, etc for the hydrolysis process. When the concentration is low, enzyme activity will change mainly with temperature. Here enzyme powder will be directly added into the reaction system.Second, the enzyme was deactivated by boiled water and no extra enzyme protective was needed. The process of casein hydrolysis was analysis qualitatively with HPSEC at the wavelength of 214nm. It was found that there were nine peaks during the process, in which peptides with larger molecular weight broke down to smaller ones. The hydrolysis at the beginning is much faster than anytime, and the distribution of products will be stable in the end. Finally, all the ingredients were divided into four lumps, one of which is insoluble and the other there are soluble. The linear connection between lumping component concentration and the area of peaks will be easily obtained by chromatographic analysis, through which we can get the concentration distribution of all the lumping components. Four lumps kinetic model was established on the basis of hydrolysis mechanism and hypotheses about the process. After the intrinsic kinetic constants of each lump had been measured, the hydrolysis constants were calculated and the mean error was 11.6%. That means there are some problems to be solved by the further research in the lump method and hypotheses. In short, lumping method is an effective way to study the complex reaction of proteolysis. It can be applied to the investigation of other systems and need a further discussion in some aspects.