Study On The Technology Of Degradation Pesticide Residue In Fruit And Vegetable

Chemical methods were used in this experiment such as peracetic acid, hydrogen peroxide, calcium hypochlorite, ozone etc to dispose respectively of the pesticide residue including methamidophos and omethoate in cole, cabbages and apples under different conditions. And the effect on pesticide residue removal has already been detected, better conditions of different disposal agents were confirmed. Meanwhile, in order to determine the best dispose conditions, the effect on different disposal agents under different conditions in nutrition quality of cole, cabbages and apples was mensurated. Finally, making use of gas chromatogram-mass spectrum method(GC-MS), degradation products of pesticide residue were identified and analyzed. So the security of the degradation methods of pesticide residue that the experiment adopted can be evaluated. The results of the experiment are as follows:1. The effect of hydrogen peroxide on degradation and removal to dispose of methamidophos and omethoate in cole is notable in some degree. The effect on omethoate are better than on methamidophos. Among the disposals, the effect on methamidophos is best if the cole is disposed of with the concentration of hydrogen peroxide of 1 % for lOmin. and this method can make the rate of enzyme inhibition reach 37.120%. Similarly, concentration of 9% and lOmin should be the best condition to degrade omethoate. The rate of enzyme inhibition can be 24.315%. From the appearance of cole after disposal, some cole changed color and withered. Therefore, it should not be recommend to be used as pesticide residue remover in fruits and vegetables.2. Peracetic acid has the effect on degradation and removal in some degree to treat methamidophos and omethoate in cole. Compared with the contrast, the remains of pesticide residue decreased strikingly. Among the disposals, the effect on methamidophos is not very good. Each amount of pesticide residue disposals has not reach the demand of standard in the country. Comparatively, the effect on omethoate is better. And the best condition is the concentration of 0.02% with lOmin. The rate of enzyme inhibition reached 39.075%. However, after disposal, the color of a great deal of cole has changed, and much has withered. So from the appearance of cole, Peracetic acid should not be used as disposer.3. With the concentration of ozone of 400mg/h to treat cole for 10~20min, the degradation and removal can reach a better level to dispose of methamidophos and omethoate. But concerning about the influence on nutritional components, it is suggested that the timeshould not be too long. The degradation and removal can just reach the best point to treat those in apples and cabbages for lOmin with the concentration of ozone of 400mg/h. Furthermore, the influence on nutritional components is the least.4. The better concentration of Calcium hypochlorite to remove methamidophos in cole is 300mg/L, and the time should be 10~20min. Considering to the influence of nutritional components , the suggestion is that disposal time should not be too long.And the disposing condition (400mg/L, lOmin, and pH4) is the best to remove omethoate in cole. The condition (300mg/L, 20min,and pH4) is the best to remove organophosphorus pesticide residue in cabbages. That to remove organophosphorus pesticide residue in apples is 500mg/L, 10min,and pH4.5. According to the results of the experiment, synthetically considering to the effect on degradation and removal, quality and appearance of fruits and vegetables, it is a comparatively perfect method to use ozone and Calcium hypochlorite to remove organophosphorus pesticide residue.6. After methamidophos and omethoate are treated with ozone and Calcium hypochlorite, new degraded productions passed GC-MS has not been detected in aether extraction phase in samples. As the substance aether extracted are un-polar and indiscerptible, it can be deduced that degradation product is high-polar substance which is easy to dissolve in water. In the course of using ozone and Calcium hypochlorite practically to degrade pesticide residue in fruits and vegetables, the polar degrading product can easily dissolve in water and be washed away. Un-polar and hard-to-wash substance won't be produced through this process.It is concluded that the security is credible to use ozone and Calcium hypochlorite to degrade organophosphorus pesticide residue in fruits and vegetables.