The Decrease Of Chlorpyrifos Residues In Lentinus Edodes During Food Processing

With the enhance of the standard of living, pesticides residues in vegetables get moreand more attention. So how to minimize the pesticide residues table vegetables andreduce the harm to human body become the research focus in recent years. This paperstudies elimination of chlorpyrifos residues from Lentinus edodes by foodprocessing. The main results are listed as follow:1.The extraction and analytical method of chlorpyrifos on Lentinus edodes was setup.Chlorpyrifos and profenofos residue was extracted with acetonitrile from Lentinusedodes samples and then analyzed by GC. Temperature of injector and detector was240℃and300℃,respectively,and basic heating pattern of the column oven wasshowed as follows: initial temperature,100℃,holding time,1min,programrate,20℃/min;final temperature,190℃,program rate,2℃/min, final temperature210℃,holding time,1min.Under these conditions, the retention time for chlorpyrifos was10.00min and limit of detection was0.2ng.The recovery rates from fresh Lentinusedodes with concentrations of0.1mg/kg,1mg/kg,10mg/kg were82.6％～98.9％. Therecovery rates from water with concentrations of0.1mg/L、0.5mg/L和1mg/L were95.7％～99.6％. The recovery rates from fried Lentinus edodes with concentrationsof0.1mg/kg,1mg/kg,10mg/kg were93.2％～94.7％.2.Compared the elimination effect with different cleaning methods by determiningthe residual levels of chlorpyrifos residues on Lentinus edodes. The results indicatethat: In most cases, washing operations led to a gradual decrease in residue levels,particularly washing with detergents or running tap water. The results indicated thatwashing with detergents led to28.95～100.00%loss in pesticide residues. Thechlorpyrifos at level of0.39mg/kg was completely removed after washing withrunning tap water, detergents or mild water.3.Compared the elimination effect with different preservation methods bydetermining the residual levels of chlorpyrifos residues on Lentinus edodes.Theresults indicate that: Controlled atmosphere and cold storage can be a significantremoval of chlorpyrifos residues. The removal of chlorpyrifos in Lentinula edodes bymodified atmosphere methods is superior to the removal of chlorpyrifos residues bycold storage. 4.Compared the elimination effect with different drying methods by determiningthe residual levels of chlorpyrifos residues on Lentinus edodes. The results indicatethat:4kinds of drying methods can reduce chlorpyrifos residues in Lentinula edodes.However, the removals of them were different. The removal rate of chlorpyrifoswas22.35%～62.97%on Lentinula edodes freeze-dried for6days. The removal rateof chlorpyrifos was73.29%～92.51%on Lentinula edodes dried for12hours.Lentinula edodes decreases with the initial removal of chlorpyrifos residues in thedrying or freeze-dried conditions. The removal rate of chlorpyrifos was54.46%～94.25%on Lentinula edodes dried in the shade. The removal rate of chlorpyrifos was43.54%～90.41%on Lentinula edodes dried in the sun.5.Compared the elimination effect with different cooking methods by determiningthe residual levels of chlorpyrifos residues on Lentinus edodes. The results indicatethat:4kinds of drying methods can reduce chlorpyrifos residues in Lentinulaedodes.However, the removals of them were different. The removal rate ofchlorpyrifos was largest of its73.24%～88.53%on Lentinula edodes fried in oil for10mins. The removal rate of52.51%~64.40%on Lentinula edodes fried was secondonly to the removal rate of chlorpyrifos on Lentinula edodes fried in oil.The removalrate of chlorpyrifos was smallest of its3.20%～20.47%on Lentinula edodes bymicrowave heating and the removal rate is also growing with the increase ofLentinula edodes initial residue.The removal rate of6.35%～88.55%on Lentinulaedodes was only higher than the removal rate of chlorpyrifos on Lentinula edodes bymicrowave heating.