茶树油清除豇豆农药残留的效果

为研究茶树油清除果蔬农药残留的效果,该试验选取豇豆为供试材料,以不同浓度的茶树油和水溶性茶树油等清洗处理,利用气相色谱和气相色谱-质谱联用检测豇豆内有机磷类、拟除虫菊酯类和氨基甲酸酯类的农药残留量,计算农药清除率。供试7种农药中,水胺硫磷、马拉硫磷、氧乐果、三唑磷、毒死蜱、氯氰菊酯和速灭威在豇豆中的初始浓度分别为:20.395、1.690、6.524、10.719、0.160、12.104和23.057mg/kg。茶树油处理后检测结果表明,茶树油具有清除残留在豇豆中农药的能力,清除效果随茶树油浓度增加而增强;清除有机磷类农药效果较拟除虫菊酯类和氨基甲酸酯类农药明显。茶树油比去离子水、市售果蔬农残清洗剂清除农药残留效果显著,同时,相同浓度的水溶性茶树油比相应茶树油清除农药残留能力强。0.8%水溶性茶树油清除效果最佳,清除率分别为水胺硫磷80.48%,马拉硫磷94.54%,三唑磷82.79%,毒死蜱84.58%,氧乐果72.20%,氯氰菊酯80.51%,速灭威72.21%。通过研究结果可知,茶树油可作为有开发前景的果蔬清除剂。

Effects of tea tree oils on removing pesticide residue in cowpea

Abstract: Pesticides are widely used as an insurance policy against devastating crop losses from pests and diseases. Excessive usage of pesticides may lead to contamination of the crop and the environment, eventually posing a risk of pesticide-related illnesses to humans. Previous literature has shown that water washing is only partially effective in removing pesticides, and in the case of liposoluble pesticides, a cosolvent must be used as an adjuvant. Recently, naturally occurring adjuvants are gaining prominence over synthetic chemical compounds. Tea tree oil (TTO, the oil of Melaleuca alternifolia), a natural, volatile essential oil, is mainly extracted by steam distillation from the fresh leaves and terminal branchlets of the plant. It has attracted significant interest due to its antifungal, antiviral, and antibacterial bioactivities. However, to the best of our knowledge, there are fewer experimental data evaluating its efficacy in the removal of pesticide residues. In this study, the effects of TTO on removing pesticide residue were carried out in the cowpea. Volume:volume (v:v) concentrations of 0.05%, 0.1%, 0.2%, 0.4% and 0.8% of TTO and water soluble tea tree oil (WTTO) in water were used to remove a standardized pesticide mixture (organophosphorus, pyrethroid, and carbamate compounds) from cowpeas. Sample pretreatment (pesticide application to cowpeas) was performed according to agricultural industry standards. The objective pesticide residues in cowpeas were assayed by gas chromatography (GC) and chromatography-mass spectrometry detection (GC-MS), and then the clearance rate was calculated. The results showed that TTO was able to remove the three kinds of pesticides from cowpeas. Moreover, the removal efficiency increased with increasing concentration of TTO. The effect of clearing organophosphate was much more obvious than that of either pyrethroid or carbamate. It was suggested that small liposoluble molecules of TTO rapidly infiltrate the cowpea surface to dissolve the organophosphate pesticides depending on the compatibility principle. For carbamate pesticides, such as carbofuran, owing to its high polarity, TTO could not infiltrate into the internal of cowpeas to dissolve the residuals, resulting in the lower clearing efficiency. In conclusion, to remove pesticide residues, the commercially available extract TTO was more effective than deionized water in removing pesticide residues from fruits and vegetables. In comparison, WTTO was even more effective in removing pesticide residues than the same concentration of TTO. Among all treatments, 0.8% WTTO showed the greatest removal efficiency. The removal rates achieved by WTTO were as follows: 80.48% for isocarbophos, 94.54% for malathion, 82.79% for triazophos, 84.58% for chlorpyrifos, 72.20% for omethoate, 80.51% for cypermethrin, and 72.21% for meta-tolyl-N-methylcarbamate (MTMC). Therefore, TTO is expected to be useful as a fruit and vegetable cleaning adjuvant.