The Extraction Of Beer Yeast Glucan And Removal Of Fluoride In Antarctic Krill

Brewer’s yeast glucan is widely present in the cell wall of yeast for brewing beer.Every 1000 tons of beer can produce 1 to 1.5 tons of beer yeast. Each year, China can produce approximately 500~750 thousand tons of beer yeast, which brings rich resources. Yeast glucan is a good immune active polysaccharide, which has the active functions of anti-cancer, antiviral, lowering cholesterol, and strengthening immunity.Antarctic krill live in Antarctic waters, whose number exceeds 650 million tons.It contains rich protein, minerals and unsaturated fatty acids, which can protect cardiovascular and lower blood lipid. However, the fluorine ions in Antarctic krill’s body seriously exceed the normal level, which greatly limits its utilization. Therefore,research on defluorination of Antarctic krill is imminent. Carboxymethyl chitosan contains carboxyl, amino and other reactive groups, which can be used as a biological adsorbent with its good chemical adsorption. Glucan, with its unique triple helical structure, is also widely applied in adsorbing mycotoxins in the animal feed.Combining carboxymethyl chitosan and glucan to make composite microspheres to adsorb fluorine ions has good removal effect and it is easy to be separated withshrimp protein.Based on the waste beer yeast cell wall as a raw material, this research adopts microwave- enzyme-alkali extraction of yeast glucan and makes the obtained glucan and carboxymethyl chitosan into composite microspheres to study the adsorption characteristics of the microspheres on fluorine ion and ability of removing fluorine ion in the Antarctic krill. Main results for this study are as follows:(1)Microwave- enzyme- alkali extraction of yeast glucan, 7 factors 2 level selected significant factor, the response surface optimized glucan extraction technology and infrared detection and identified by IR, using High Performance Liquid Chromatography to determine the distribution of glucan molecular weight and the composition of monosaccharide. The results showed that three factors significantly affect the extraction of glucan, they are microwave power, heating time and the amount of enzyme. The optimum parameters of extraction are microwavepower 420 W, heating time 5min, enzyme dosage 2550U/g, total sugar actual value obtained was 87.94%, approximate to the predicted value 87.44, shows that through the response surface method of glucan extraction model is reasonable and reliable,better fitting degree, has the use value; infrared measurement structure of glucan, near1372 cm-1 is the characteristic absorption peak of beta-1, 3 key, near 1041 cm-1and1078 cm-1 are the C-O absorption peaks of polysaccharide, 891 cm-1 is the characteristic deformation vibration beta-D-pyranose C-H absorption peak, Prove the extracted samples for beta glucan; The molecular weight of the dextran is about 6.02 x 105 da; The composition of monosaccharide for a single glucose.(2) The microspheres is prepared by using carboxymethyl chitosan and glucan as raw materials, which optimized the carboxymethyl chitosan and glucan added proportion and studied the influence of reaction solution p H, temperature, reaction time, additive amount of microspheres and initial fluorine ion concentration on the desorption performance for fluoride removal of microspheres. Fitting desorption rate by Lagergren rate equation and pseudo secondary quasi level rate equation to study dynamic adsorption performance microspheres, by Langmuir theory formula fitting for 50 ℃ under the microspheres of fluorine ion adsorption isotherm, adsorption thermodynamics research microspheres. The results showed that the microspheres made by 5% of carboxymethyl chitosan and 1% of glucan, in the cases of the elastic and hardness can meet the need of experiment, the desorption of fluorine ion is best;when PH is 4, the desorption capability is best, and the changes of the temperature has little influence on it, at 8 h carboxymethyl chitosan- glucan composite microspheres of fluorine ion desorption capacity of the largest, as the microspheres increases, with the increase of adding amount of its desorption ability of fluorine ion also increases,the initial concentration of fluorine ion is within the scope of 0.5 to 1.5 mg/m L,desorption capacity is on the rise, within the scope of 1.5 to 3.5 mg/m L, a downward trend; kinetics model of Microspheres adsorbed fluoride ion accord Lagergren second adsorption, thermodynamic model of Microspheres adsorbed fluoride ion accord Langmuir model, is the desorption among single molecules.(3)The microspheres were applied to the Antarctic krill protein defluorination,artificial neural network were used to optimize defluorination techniques, three-layer neural network model of the 3×3×1 can simulate the removal process, the use of low concentrations of acid desorption saturation microspheres fluoride ion desorption,then a low concentration of lye its regeneration. The results showed that: when theaddition amount of 0.908%, p H of 5.64, the time of 4h, the desorption rate of fluoride ion can reach 85% at this time; the lye to regenerate the best time for 10 min;Microspheres with two repeated regeneration of fluorine ion desorption rate can reach80%.Microwave- enzyme- alkali distillation yeast glucan minimizes the time of extraction and reduces the environmental pollution to the environment;carboxymethyl chitosan- gluconic composite microspheres realizes the biological removal of fluoride in Antarctic krill, which increases the utilization of the Antarctic krill protein.