Residual Dynamics Of There Pesticides In Edible Fungi And Their Removal Using Various Methods

This paper did research on the degradation dynamics of fenpropathrin andlambda-cyhalothrin and pyraclostrobin in edible fungi and substrates, as well as mushroomfruiting compound absorbed from the substrates of three pesticides transfer phenomenon. Andexplore several ways to remove three kinds of pesticide residues in edible fungi.1. Establish residues analytical methods of pyraclostrobin and lambda-cyhalothrin andfenpropathrinThree pesticides were all extracted by acetonitrile, purified by Florisil columnchromatography. Lambda-cyhalothrin, fenpropathrin GC-ECD detection, constant volume ofn-hexane; Pyraclostrobin,1100HPLC, UV detector testing, constant volume of methanol. Theaverage recovery of pyrethroids in citrinopileatus fruiting bodies and substrates was88.22%-100.78%,coefficient of variation was3.4%-7.7%and the substrates was84.46%-96.30%coefficient of variation was3.6%-7.7%; pyraclostrobin in citrinopileatusfruiting bodies was84.46%-95.28%, coefficient of variation was2.5%-6.3%and the substrateswas90.36%-93.26%coefficient of variation was2.7%-6.8%The minimum detectableconcentration of fenpropathrin and lambda-cyhalothrin in edible fungi and substrates was0.005mg·kg-1and The minimum detectable concentration of pyraclostrobin was0.006mg·kg-1.Thisproved that the method was accurate and feasible.2. Degradation dynamics of pyraclostrobin and lambda-cyhalothrin and fenpropathrinDegradation dynamics experiment consist of spraying pesticide，fruiting body and sprayingcompound in substrates.When the diameter of fruiting body was2cm began to spray pesticide.The experiment results showed that the residue dynamics of pyraclostrobin、lambda-cyhalothrin and fenpropathrin in edible fungi and substrates are in line with kineticequation. Half-life of Fenpropathrin, lambda-cyhalothrin in citrinopileatus fruiting bodies, andsubstrates and residual pyraclostrobin in pleurotus ostreatus, citrinopileatus and substrates were1.4d,20.3d;1.8d,23.8d;2.9d,2.8d,14.1d. The half-life of pyraclostrobin、lambda-cyhalothrinand fenpropathrin in edible fungi was short and the substrate was longer.Residue harvest time ofpyraclostrobin and lambda-cyhalothrin and fenpropathrin in edible fungi were less than pesticideresidue limits standards.3. The appearance of fruiting body absorbing pesticide from substratesThe experiments took the pesticides even before sterilization spray compound in substrates and then sterilize12hours. Experiments showed that there is a greater impact on the residualamount of the pesticides sterilization. Three pesticides degradation rate after sterilization werebetween30%-60%. This proves that the poor stability of pesticides thermal and provide areference for the training material mix pesticides in substrate. As can be seen from theexperimental results of fruiting, there are only applied to the first crop of fruiting bodiescollected fenpropathrin a small amount of residue, the other two pesticides were not detected.This proved that during fruiting growth period, there will not be too much absorbing ofsubstrates; During the time of prevention of diseases and pests, implementation of substratemixed with the pesticides was a safe and reliable method.4. Research method of removal of three kinds of pesticides of edible fungiPreparation of selected pollution mushroom by immersion method. This experiment studiedfive different treatment methods of storage, UV irradiation, ultrasonic, ozone immersion method,biochemical degradation extract to test treated edible fungi and found that they have differentoutcomes in three pesticides.Storage method selected three different temperatures of5℃,20℃,40℃and threedifferent storage times of12h,24h,48h to test mushroom pesticide removal rate. We found thatthe higher the temperature, the higher and the longer the storage time the removal of pesticides.Also, in edible fungi fenpropathrin, when the temperature reached40℃/48h, the degradationrate was up to55.2%. UV irradiation exposure selected three times:2min、6min、15min. Wefound that the longer the exposure time, the more obvious of pesticide removal. Through thestudy of different experiments and different ultrasonic power ultrasonic time,lambda-cyhalothrin best ultrasonic time was15min, pyraclostrobin、 fenpropathrin bestultrasonic time was20min, pyrethroid-processing best ultrasonic power of120W,pyraclostrobin best ultrasonic of200W, removal rate reached86.7%-93.1%.Lambda-cyhalothrin and fenpropathrin best ozone immersion time was20min, it was up to85.4%. And the pyraclostrobin optimum treatment time was30min, it was up to79.5%.Take the Pleurotus ostreatus which have pesticides into the diluent of degrading enzyme.When preparations for the enzyme is20%and fenpropathrin degradation rate is92.5%, By theorthogonal experimental design and analysis, we determined the best medium combination:response time20min、reaction temperature30℃、dietary alkali2%, the degradation rates was97.8%.