Study On Nondestructive Removal Of Pesticide Residues In Chinese Medicinal Materials By Subcritical Fluid

Chinese medicinal materials have various pharmacological and health functions,but the problem of excessive pesticide residues has seriously affected their edible value and the development of related industries.So far,there are many studies on the degradation of pesticide residues by subcritical fluid,but most of them focus on the matrix of fruits and vegetables.Only part of the studies are about the removal of pesticide residues in Chinese medicinal materials,and only for one or several kinds of pesticides in a class of Chinese medicinal materials.Therefore,it is very crucial to synchronously and efficiently remove more types of pesticide residues with different polarity in Chinese medicinal materials.In this study,the removal of pesticide residues in Lycium barbarum by subcritical fluid was systematically studied.The technological conditions for simultaneous removal of pesticide residues with different polarity were also optimized.The removal efficiency of subcritical fluid for various polar mixed pesticides with different concentrations of Lycium barbarum,Chinese jujube and Auricularia auricular was tested.The pilot scale experiment was carried out to verify the results,meanwhile,the content changes of active components such as polysaccharide and betaine in Chinese medicinal materials before and after the treatment were determined.Specific research contents and results are as follows:(1)Establishment and optimization of subcritical fluid technology for the removal of seven kinds of pesticide residues with different polarity in Lycium barbarum.Pesticides were added into Lycium barbarum,then by single factor experiment,the effects of extraction agent type and proportion,temperature,time and extraction times on the removal rate of pesticide residues were investigated.Response surface experiments were carried out with the removal rates of carbofuran and carbenazim as response values.The optimized process conditions were as follows: extracting agent butane:methanol,3.43:1(v/v);extraction temperature,35.58℃;extraction time,50 min and extraction times,2.Under these conditions,the simultaneous removal rates of carbofuran and carbendazim could reach 92.89% and 91.88%,respectively.(2)Research on the removal of pesticide residues with different concentrations in various Chinese medicinal materials by subcritical fluid.The study chose 10 pesticides with different polarity from 8 types of typical pesticides in common use and then added them to Lycium barbarum,Chinese jujube and Auricularia auricular.High,medium and low concentration were set for each pesticide.It was found that the removal rates of 6 pesticides in Lycium barbarum were all above 90%,and the removal rate of carbendazim was the highest,which was 92.87%.In Chinese jujube and Auricularia auricular,the removal rates of carbendazim,cyhalothrin and cypermethrin were above 95%,and the removal rates of imidacloprid,fipronil and chlorpyrifos were between 90% and 93%.It showed no significant difference in the removal rates of each pesticide among high,medium and low concentration groups(p > 0.05).The residues of 10 kinds of pesticides with different concentrations and polarity in three kinds of Chinese medicinal materials could be significantly reduced by the subcritical fluid extraction technology.(3)Pilot experiment for removal of pesticide residues and determination of active components in Chinese medicinal materials.By enlarging the quantity of Lycium barbarum,Chinese jujube and Auricularia auricular,it was discovered that in Lycium barbarum and Auricularia auricular,the removal rates of 7 pesticides were above 80% and the removal rate of carbendazim was the highest,which was 95.73%.The removal rates of 6 pesticides in Chinese jujube was above 80%,and the highest rate reached 93.68%.After treatment,the appearance and main bioactive components of three herbs had almost no significant changes.In this thesis,a subcritical fluid system,which applied in removing different types of pesticide residues with different polarity and concentrations in more kinds of Chinese medicinal materials was established,and it could not only be widely used for the removal of all kinds of pesticides on the market,but also almost completely retained the main active components of Chinese medicinal materials.This study provides a solution for industrialized application of the removal of pesticide residues in Chinese medicinal materials.It is of great significance to the guarantee of the sustainable development of Chinese medicinal materials and food safety.