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Hyaluronic acid is a macromolecular mucopolysaccharide, has unique rheological properties, special physiological role and strong water retention capacity, and therefore a wide range of applications in the health food, cosmetics, medicine, and other fields. Explore the rheological properties and its application on microbial fermentation production of hyaluronic acid, hyaluronic acid, the main conclusions are as follows: 1. The our laboratory mutagenesis horses Streptococcus (streptococcus eqius) NC168 fermentation medium and culture conditions were optimized. First select the carbon and nitrogen sources, inorganic salts single factor test quadratic orthogonal rotation test, and on this basis, to obtain optimal medium group was divided into: yeast extract 3.00 g/100mL, peptone 2.00 g/100mL , in glucose 0.50 g/100mL, MgSO4 0.15 g/100mL. Optimized medium components based on the effects of temperature, pH, shaking speed, medium volume and inoculum size on the production of HA and orthogonal experimental design, the better the fermentation conditions: temperature 37 ℃, pH 7.8, shaking speed 200 r / min and 250 mL flask fluid volume 30 mL, optimized shake flask fermentation production HA production was 224.52 mg / L. Investigated the initial sugar concentration, temperature, stirring speed and pH 5L fermentor production of hyaluronic acid, explore the batch fermentation conditions and kinetic characteristics of the bacterial fermentation kinetics model to arrive at a more optimization of culture conditions: initial sugar concentration of 30 g / L, temperature 35 ℃, stirring speed of 200 r / min, the pH value of 7.0, in this condition, the production of hyaluronic acid 1.92 g / L. Cell growth and HA synthesis the nonlinear fitting determine the biomass fitting equation Logistic model best correlation coefficient R2 up to 0.999, and the the HA synthetic fit the equation to Slogistic model best correlation coefficient R2 of 0.996 glucose consumption process DoseResp model to fit the correlation coefficient R2 = 0.991. quaternary ammonium salt precipitation and ethanol precipitation combined with hyaluronic acid in the fermentation broth were isolated and purified. Hyaluronic acid concentration in the fermentation broth, CTAB amount of precipitation temperature and time, NaCl concentration and ethanol concentration, temperature, and other factors, the impact of the extraction rate of hyaluronic acid and protein content. The test results show that the hyaluronic acid concentration in the fermentation broth was 0.80 g / L, a 15% CTAB solution Add the volume of the fermentation broth, a precipitation temperature of 35 ° C, the precipitation time 2 h, NaCl concentration 1.5 mol / L, the ethanol final concentration of 70% hyaluronic acid yield can be as high as 96.62%, protein removal rate was 86.09%. Different molecular weight hyaluronic acid and hyaluronic acid prepared in this laboratory study Rheometer system investigated different concentrations, different relative molecular mass, temperature and pH value of the hyaluronic acid solution fluid properties and viscoelastic. The results indicate that hyaluronic acid solution viscosity with increased shear rate gradually decreased, the performance of a typical shear thinning non-Newtonian fluid; enhanced when the solution concentration increases, the shear thinning behavior of the fluid; hyaluronic acid solution viscosity, its molecular weight is proportional to, and is inversely proportional to the temperature of the solution; reduced elastic behavior feature enhancement with hyaluronic acid molecular weight increases, the viscous behavior of the fluid characteristics. 5 different hyaluronic acid and carboxymethyl cellulose (CMC), the influence of the added amount of milk viscosity results show that the apparent viscosity and shear stress of the milk sample is increased gradually with the increase in the amount of hyaluronic add, change trend, add CMC milk samples, but its higher viscosity. Investigated Add milk after HA and CMC thixotropic, found that when the added amount is less than 0.1%, the milk little change in viscosity in the range of shear rates, the performance of a Newtonian fluid characteristics, while when the addition amount of 0.2%, milk lower viscosity with increasing shear rate, expressed as a pseudoplastic fluid, changing the type of fluid of the original milk.
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