Study On The Method Of Culturing Aspergillus Niger From Cassava Alcohol Residue As Raw Material And Extracting Natural Water Soluble Chitosan

Cassava residue is the product of cassava processing,which contains many of polysaccharides and protein and other nutrients.Cassava residue is mainly cassava alcohol residue and cassava starch residue,However,cassava residue in the untreated conditions of feeding poultry will have some toxic effects on poultry,direct burning will cause some pollution to the environment.Aspergillus niger is a very common Aspergillus fungus,which was widely used in food,industrial enzymes and other fields..In this reserch,we use Aspergillus niger to fermentae cassava residue in order to produce chitosan.The extraction,preparation and application of chitosan from Aspergillus niger were combined.In this paper,the hydrolysis of cassava alcohol residue was carried out by dilute nitric acid,and the residual nutrient components in cassava wine residue were fully utilized by Aspergillus niger fermentation of cassava alcohol residue.The chitosan was modified by ionic liquid.The specific research contents and conclusions are as follows:1?Pretreatment of cassava alcohol residue with 0.5% HNO3 to achieve the purpose of hydrolyzing cassava alcohol residue and detoxification.The results showed that the yield of reducing sugar was up to(30.02±0.22)% and the yield of protein reached(4.69±0.20)% under the microwave power of 400 w combined with microwave and ultrasonic radiation degradation 5 minutes.2?The results showed that the optimum culture conditions were as follows: 4 g of peptone was added to each 200 mL of hydrolyzate,5 mL of the bacterial suspension at a concentration of 1.5×107 / mL was added,the pH was adjusted to 6.5,the culture temperature was 30?and cultured for 3 days.3?The Aspergillus niger cells were treated by alkali / urea system and chitosan was extracted.The results showed that: Chitosan yield can be achieved(13.72±0.8)%,the degree of deacetylation was(96.85 ± 0.53)%.4?Water-soluble N-acetylated chitosan was prepared under anhydrous system using ionic liquid as solvent,The results showed that: The yield of water-soluble chitosan prepared by BMIMCl as solvent can reach 91.2%,the degree of deacetylation can reach 52.75%,the yield of water-soluble chitosan can be up to 86.5% with BMIMAc as solvent,and the degree of deacetylation can reach 48.99%.