Research On New Antimicrobial Material From Silkworm Pupa Of Chitin

China is the largest silk country and the dry chrysalis yield more than 100,000 tons every year which accounts for more than 70 percent in the world's.Because Chrysalis as a by-product of reeling has a unpleasant smell,it has not been well utilized except for livestock and poultry feed.Chitin and its derivatives are widely used in many fields for diversity function,Producing chitin / chitosan has formed industry from shell of shrimp and crab.According to research,the silkworm puparium contains 33%-44% chitin,more than that of shrimp and crab's,and the salt less than that of them,so it is a better resources for extracting chitin.The large number of chrysalis can be collected from filatures.Because of its extensive-sources,low-cost,high economic value,we can change waste into resources.So,it is essential to study the chitin / chitosan process from silkworm puparium detailed.The dissertation test takes puparia of silkworm Bombyx mori as raw materials.The acid alkali method (low concentration acid removing minerals,low concentration alkali removing protein,H₂O₂ decolor and high concentration alkali deacetylation),was applied for extraction of chitin and chitosan,and also study on antimicrobial ofchitosan,the main results were reported as follows:1.Research on the best extraction chitin from silkworm puparium and the quality testing(1)When the study on preparation of chitin,the test used single-factor experiment,in which the influence of reaction conditions on chitin characteristics was investigated,such as acid concentration,time of acid treatment,temperature of acid treatment,alkali concentration,time of alkali treatment,temperature of acid treatment.According to the quality index and economy,the best extraction condition was:HCI concentration was 3%,treatment temperature was 30℃,time was 22 hours;and NaOH concentration was 5%,treatment temperature was 85℃,time was 4 hours,and 10%H₂O₂ decolored.(2)Results indicated the chitin was white tabular solids,the productivity was 32%～38%,water content was 5%～10%,ash content was 0.63%～0.81%,nitrogen content was 5.86%～6.02%.Compared with the standard of shrimp and crab's chitin(water content was≤10%,ash content was≤1.0%,nitrogen content was 6.2%～6.5%).Its qualities indexes reached that of shrimp and crab's edible chitin,contributed to the deep development and utilization.2.Research on the best extraction chitosan from chitin and the quality testing(1)In order to study on the best extraction of chitosan,the test applied correctitude design,which contained 3 factors,(such as alkali concentration,treatment time and time of treatment)and 4/5 levels. According to analysis of variance,the result showed:NaOH concentration,temperature and time were much contribute to chitin deacetylace reaction.NaOH concentration and temperature had a significant synergy to impact on deacetylace reaction;However,the treatment time and temperature were relative independence on it.The result showed the best condition was that alkali concentration was 50%,treatment time was 18h,and temperature was 90℃.(2)It was shown that chitosan was white tabular solids or powder,water content was 8.1%,ash content was 0.67%,viscosity was 41mpa.s,molecular weight was 5×10⁴,Degree of deacetylation was 95.6%,Compared with the standard of shrimp and crab's chitosan(chitosan was white tabular solids or powder,water content was≤10%,ash content was≤1.0%,viscosity was 30mpa.s～3000mpa.s,Degree of deacetylation was≥85%),Its qualities indexes reached that of shrimp and crab's edible chitosan.3.Research on Antimicrobial of chitosan from silkworm pupariumSelect DD.90.4%and DD.95.6%chitosan for antibacterial to StapHyloccus aurueus,Escherichia coli, Candida albillus and Bacillus stearothermopHilus Donk.(1)The result was showed:among PH4.5～6.5,DD.90.4%and DD.95.6%chitosan could play a significant antibacterial effect,however,above pH 6.5,they weaken and even did not work out.It proved the pH affected the inhibitory of chitosan.In the acid environment,chitosan easily interact with microorganisms by negative charge.Therefore,under the conditions of low pH value environment,the inhibitory effect was better than that of high pH values.(2)In the concentration from 0.100%to 0.125%with DD.90.4%chitosan,the order of advantages to antibacterial was:Escherichia coil＞Bacillus stearothermopHilus Donk＞StapHyloccus aurueus＞Candida albillus;in the concentration from 0.100%to 0.125%with DD.95.6%chitosan,the order of advantages to antibacterial was:StapHyloccus aurueus＞Bacillus stearothermopHilus Donk＞Escherichia coli＞Candida albillus.The purified DD.90.4%of chitosan,it was great improvement on the antibacterial activity to Candida albillus,when the concentration reached 0.125%,the inhibitory rate was more than 95%.(3)The minimum inhibitory concentration of DD.90.4%chitosan was:StapHyloccus aurueus was 0.125%,Escherichia coil was 0.100%,Bacillus stearothermopHilus Donk was 0.125%,and DD.95.6% chitosan was:StapHyloccus aurueus was 0.075%,Escherichia coli was 0.100%,Bacillus stearothermopHilus Donk was 0.125%.The results showed that chitosan extracted from silkworm puparium was better than that of shrimp,crab's on antimicrobial.The results provided a theoretical basis for extracting chitin from puparia of silkworm Bombyx mori and developing new antibacterial product from chitosan.