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Xylitol is a sugar alcohol functionality , they can prevent tooth decay , as a diabetic sweetener alternatives , can also play a hepatoprotective hepatoprotective role . The industrial production of xylitol by chemical hydrogenation , compared with the method , microbial fermentation method for its production conditions easily control the production process is non-toxic and non-polluting , low cost , become the focus of current research . Straw hydrolysis process some of the substances interested microbial growth inhibition produced needs to be removed in the pre-fermentation , in order to improve the rate of xylitol . Straw hemicellulose hydrolyzate to corn as the raw material was decolorized with activated carbon and ultrafiltration , nanofiltration desalination , and bleaching, desalted hydrolyzate for xylitol fermentation preliminary study findings : activated carbon decolorization best conditions : activated carbon added amount of 27.7g / L, temperature of 57.92 ° C time of 21.28min decolorization rate of 70.9074% , xylose loss rate of 7.65525% . Under this condition, to obtain the actual decolorization rate of 75.892% , 10.694% of the loss rate of xylose . Comprehensive study on the basis of active carbon used ultrafiltration pressure , temperature , time , flow rate , feed concentration on decolorization effect , determine the ultrafiltration conditions : pressure of 0.1MPa, temperature 30 ℃, time 30min, flow rate 6L / h, the material was concentrated to 2 times . Under this condition, subjected to ultrafiltration to obtain the actual decoloration rate of 60.532% , xylose loss rate of 9.049% . The decolorization the hemicellulose hydrolyzate nanofiltration desalination , the of Nanofiltration pressure , temperature , time , pH , feed concentration , desalting effect , determine the nanofiltration conditions : pressure 0.6MPa, temperature 20 ° C , time 40min , concentrated feed solution 2 times the test verified desalination rate of 70.003% . Optimize the growth conditions of the Candida tropicalis 1779 , and under this condition fermentation decolorization , desalted hydrolyzate, xylose leaven conversion was 45.62% , with xylitol conversion rate obtained after fermentation of the simulated body fluid 63.91% difference compared large , so further research is needed .
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