Study On Extracting Technology Of Fat And Chitosan From Tenebrio Molitor

Tenebrio Molitor contains rich oil,protein,mineral elements and chitin.As one of the important economic insects,Tenebrio Molitor has a bright development prospect. At present,the research of Tenebrio Molitor is mainly focusing on extraction of protein,but the study of oil and chitin is still at the starting stage.The powder of microwave dried Tenebrio Molitor was used as material.The comprehensive exploitation of Tenebrio Molitor resource was studied by adopting sequential extraction method to extract oil and chitin,hoping to determine the optimum conditions.This thesis can provide basis for industrial production.The thesis was carried out of two aspects.The first aspect was to identify the optimum conditions of both Soxlet extraction method and lixiviating method for oil extraction through single-factor and orthogonal experiments.The effects of each experimental parameter on efficiency and saponification value were studied,and a comparison between the two methods was made.Results show that the optimum conditions of Soxlet extraction method were as fallow:the dosage of petroleum ether is 200mL,heating voltage is 125V,duration is 5h,material quantity is 10g,extracting time was one time.Under these conditions,the fat extraction efficiency is 32.26%,and saponification value is 202.01;The optimum conditions of lixiviating method were as fallow:solid-liquid ratio is 1:12,duration is 6h and water bath temperature is 60℃.Under these conditions,the fat extraction efficiency is 27.51%,and saponification value is 204.98.The second aspect was the technology of chitin and chitosan exaction.The fat-removed Tenebrio Molitor powder was used as material,and acid leaching method was adopted to remove ash,sodium hydroxide solution was adopted to remove protein.The optimum conditions were determined through single-factor and orthogonal experiments:using boiling water bath,NaOH concentration is 2.0mol/L, treatment time is 6h.Under these conditions,the residual protein content of chitin is below 5.0%;When HCl concentration is 2.0mol/L,treatment time is 3h,stirred under room temperatures,the residual ash content of products is below 0.20%.The degree of deacetylation is an important index of chitosan quality.This thesis used NaOH solution to deacetylate chitin.The effect of each experimental parameter on chitosan quality was studied through single-factor experiments,and the relationships among degree of deacetylation,solubility and absolute viscosity were discussed.Results show that the degree of deacetylation of product reaches 80.73%in the following conditions:Boiling water bath,NaOH concentration is 40%,treatment time is 6h,treat twice(3h each time).Increasing NaOH solution concentration and treatment temperature could be effective methods for improving the degree of deacetylation of products.When the degree of deacetylation is above 70%,the products could dissolve in 10%acetate and the solution is an oily liquid.Generally the absolute viscosity of chitosan decreased as the degree of deacetylation increased. When NaOH concentration is 40%and treatment time is 6h,the absolute viscosity of products reach maximum 133.0mPa·s.Based on the dry powder of Tenebrio Molitor,the yield of chitosan is 9.51%.