Research On Irradiation Degradation And Products Character Of Orgnaophosphorus And Pyrethroid In Fruit And Vegetable

Pesticide residues bring about potential risks on the food safety issues. Food irradiation is an effective technology for food safety without any pollution. Food safety has been focused on the state"11th five years plan". Several high-techs are welcomed to optimize the industrial structure, improve product quality and ensure food safety. Food irradiation, which is studied and applied to protect food safety, has been an important part of the national scientific and technological support.The aim of the research is to study the degradation effect of pesticide residue by irradiating fruit and vegetable, and testify that irradiation is practicable in controlling pesticide residue of fruit and vegetable, thus the application area of irradiation can be expanded and food safety would be safeguarded powerfully. The research select the typical phosphate pesticide of chlorpyrifos and the pyrethroid pesticide of cypermethrin as objects, and use sparagus and apple as the target food. The aim of the research is to answer several questions which are necessary to determine that irradiation is an appropriate technology to eliminate the pesticide residue in fruit and vegetable. These questions are: whether the pesticide residue can degradate, what the irradiation degradation products is,whether they are toxic or not,how the degradation work, and whether the quality of the fruit can received by people. The main projects and research results are as follows:1.The degradation effect of chlorpyrifos and cypermethrin under irradiation was firstly studied by using aqueous solution. The results showed that under the dose of 4kGy and the concentration of 5.0 mg/L, the degradation rate of chlorpyrifos was 90%, under the dose of 4kGy and the concentration of 2.5 mg/L, the degradation rate of cypermethrin was 60%. The research demonstrated that chlorpyrifos and cypermethrin can degradate by irradation. Initial concentration and absorbed dose can also effect the degradation of pesticide residue. The higher the absorbed dose was, the better the removal effect of pesticide residue was. The lower the initial concentration was, the more the residue was removed.2.The main irradiation degradation products of chlorpyrifos and cypermethrin aqueous solution were systematic studied and their toxicity was evaluated.Four main radiolysis products of chlorpyrifos and two main radiolysis products of cypermethrin are determined by gas chromatography tandem mass spectrometry (GC/MS) analysis method. One of radiolysis products of chlorpyrifos is the same with the degradation products of environmental water, the others were reported for the first time. One of the radiolysis products of cypermethrin is its synthetical midbod, the other one was reported for the first time. The toxicities of them were evaluated by retrieving information from the toxicological databases. 3.The irradiation degradation effect of chlorpyrifos residue in asparagus and cypermethrin residue in apple were studied and the best irradiation process has been determined. The results showed that the degradation rate reached the maximum of 30% at 8kGy. The largest content of the chlorpyrifos in vegetable is 1.0mg/kg according the Chinese Standard. If the content of chlorpyrifos in apple is 1.6mg/kg, it can be irradiated with the dose of 4kGy to achieve Chinese Standard. The degradation rate reached 30% when the dose is 4kGy, selecting this dose as the best dose, as the apple are easy to become brown when the dose exceed 4kGy. The largest content of the cypermethrin in fruit is 2.0mg/kg according the Chinese Standard. If the content of cypermethrin in apple is 3.0mg/kg, it can be irradiated with the dose of 4kGy to achieve Chinese Standard.4.By contrasting the degradation rate of pesticide residue in water solution and foods, it showed that the degradation rate in foods is far lower than in water solution. The effect of certain materials in fruit and vegetables on irradiation degradation rate was studied. The results indicate that the degradation rate of residue aqueous solution containing fruit and vegetables materials was lower than those without fruit and vegetables materials. This means that vitamin C, flavonoids and total sugar affect the irradiation degradation of pesticide in different extent.No researchers has studied on the irradiation degradation of pesticide residue in food in other contries. In China, this research has just started and the studies refers the effect and principle of irradiation degradation of pesticide residue only at present. Besides, this study includes the degradation products and their toxicities,which can provide basis knowledge of the safety of irradiation degradation products of pesticide residue in food. It has important significance on the ensurance of food safety.