Study On Production Process Of Chitosan Oligosaccharides With Specific Weight-average And Narrow MWD By Enzymatic Hydrolysis

Chitosan, which has a poor water solubility partly due to its high molecular weight, shows a relatively low bioavailability. Compared with chitosan, chitosan oligosaccharide has a good water-solubility, this feature greatly improves its bioavailability. A large number of studies have shown that chitooligosaccharides have a series of valuable biological activities, including antioxidant, antimicrobial, anti-tumor, anti-inflammatory, regulation of blood lipids and blood sugar index, enhance immunity, and activation of the intestinal flora and a variety of physiological effects.The chitooligosaccharides'biological activity is related to its molecular weight.There are many reports show that the degree of polymerization of chitooligosaccharides about6showed more great anti-tumor activity. By controlling the degradation reaction conditions can we obtain a specific molecular weight chitooligosaccharides products and this is particularly important. The chitosan degradation methods taken in the production practice are mainly the following three categories:physical, chemical, biological degradation methods. Compared with the previous two methods, bio-degradation method acquires less energy during degradation and has a high efficiency, which has a mild reaction condition, low environmental pollution and controllable reaction condition, etc, which is the the main method of the degradation of chitosan to produce chitooligosaccharides.By controlling the conditions of enzymatic hydrolysis and enzymatic hydrolysis reaction time can we gain the oligosaccharides with a specific molecular weight.With the help of membrane separation method, different membrane materials can further narrow the chitooligosaccharides molecular weight distribution and improve product purity.In chitooligosaccharides product quality control, the using of gel permeation chromatography can quickly and easily get results of chitooligosaccharides molecular weight and its distribution.Content and conclusions of this study: chitosanase enzymatic properties, including four factors such as the temperature, pH, enzyme substrates ratio, metal ion which can imitate chitosanase activity; ambient temperature, pH on the stability of xylanase, experimental results show that the optimum pH of the chitosanase was6.0, the optimum reaction temperature is45℃, the optimal enzyme substrate ratio is1:10(1mL Chitosanase mixed with lOg chitosan substrate). The concentration of substrate is between3%to5%. The activity of chitosanase stay stable within the range of pH4-8, the temperature is relatively below40℃, Fe3+,Ba2+is good for the enzyme activity while Al3+,Cu2+can significantly inhibit the enzyme activity. The dynamic viscosity values of the enzymatic reaction mixture was found by using a rotational viscosimeter, after the enzyme solution added to the chitosan colloidal solution for about10min, the viscosity turn to be stabilized. We can see that the chitosanase has an excellent degradation effect. An electronic pH meter can be used to monitor the reaction solution pH of the system. We found that the pH of the system during the reaction showed no significant changes. Contrast to IR spectra of chitosan substrate and the corresponding degradation products showed no significant change among functional groups.There were only subtle differences in the molecular chains which were cut off before and after degradation. The article also explores the application of modern membrane separation technology in the production process of the chitooligosaccharides. Investigating the volume of ultra-filtration membranes, the results of nano-filtration membrane equipment operation show that in the process of chitooligosaccharides purify and concentrate, such as feasibility of the application, ultra-filtration and nano-filtration can narrow the molecular weight distribution and improve product purity. The molecular weight of final product was determined by GPC method. The chromatographic conditions:gel permeation column: PL aquagel-OH30MIXED8μm300X.5mm, column temperature:30℃; mobile phase: acetic acid-sodium acetate (0.1mol/L1:1); flow rate:1.OmL/min; injection volume:20μm; Using differential refractive index detector; Agilent of GPC software processing by MS analysis verify that the reliability of this method is good. By controlling the hydrolysis time can we get the chitooligosaccharides products with a specific molecular weight. The use of GPC method for the determination of molecular weight data of different enzymatic hydrolysis time can guide the production practice.