The Degradation Effect And Products Analysis Of Irradiation On TeA

Mycotoxins are secondary metabolites produced by fungi, such as ochratoxin A, zearalenone, aflatoxin, deoxynivalenol and so on. The toxicities in different mycotoxins are discrepant, and all these mycotoxins cause severe pollution on agricultural products, and have a serious damage on the life and health of human and animal.In recent years, mycotoxin contamination has become the main cause threatening China's food security. Statistics from 2005 to 2014 showed that the number of relevant contravention matters of Chinese food export to the EU reached 3039, in which mycotoxin contamination accounted for 24.9% and is the highest percentage of the single event, causing great economic losses and pressure to China's export of grain and oil. Food irradiation technology is a commonly used method to eliminate the mycotoxins occurred on agricultural products, and triggers the ionization effect and chemical effect inside the food or the effect of other substances in a variety of free radical produced by water medium after radiation and food by using electron beam, X-ray, and gamma ray ionization act on food, so as to realize the preservation, improve quality, and keep the nutrition gradually rising in recent years, and is widely used in pesticidal, sterilization, anti-corrosion, preservation and to extend the shelf life of field. Tenuazonic acid(TeA) in wheat which widely pollute agricultural products is a kind of mycotoxins, and the potential hazard to human and animal can not be ignored anymore. At the moment, research at home and abroad mainly aim at the determination of contents or the improvement of the detection limit. Even the EU,USA and other developed countries don't set out a detection methods, and the reports on TeA degradation and its productions are few.This paper is based on the study of TeA, which is characterized by wide pollution, low temperature resistance, toxicity. The degradation effect of irradiation on TeA and the radiolytic products of nucleo cytoplasmic ratio make a solid foundation for the application of irradiation technology of other mycotoxins play. The object of this research is TeA. High performance liquid chromatography coupled with UV (HPLC-UV)detection is set up to measure the content of TeA, explore the effect of irradiation on degradation of extremely rules and then find major radiolytic hydrolysate by liquid chromatography/time of flight mass spectrometry(LC-TOF-MS), we can lay the theoretical foundation for the further study of the effects of TeA irradiation in wheat.(1) Establish HPLC-UV method for determination of the content of TeA. This method in tea linear range (0.05-5 ?g/mL, linear equations for y=110.46x+0.3044 and decision coefficient of 0.9999) indicates that the sensitivity of the method can meet the requirements of the detection of TeA. The minimum detection limit of the method is about 0.008?g/mL, and the minimum limit is about 0.02 ?g/mL. Instrument for the continuous sampling of the day 0.12%-0.68% for the RSD, day RSD for the 0.61%?0.65%, are less than 2%, so the method is of good precision. Establish HPLC-UV method for determination of the content of TeA in wheat. Under the three different initial concentrations, the recovery is 89.92%? 96.97% and 102.87% respectively, showing that the method can satisfy the test requirement.(2) The degradation effect of TeA is obvious after different doses of irradiation. In solution, the degradation rate of TeA increases with the increase of radiation dose. According to the change of the concentration ratio(C/Co) after irradiation, the polynomial equation y=ax3+bx2+cx+d is used to fit the radiation dose, and the correlation coefficient is 0.9573. The degradation rate of TeA increases with the decrease of initial TeA concentration in the solution. Under low concentration conditions, the degradation rate of TeA was higher at 4 kGy, the initial concentration of 1 ?g/mL degradation rate was more than 50%, while the initial concentration of 5 ?g/mL degradation rate was only 20%, and the 10 kGy was more than 50%. Under low irradiation conditions, the degradation rate of the low concentration increased rapidly, however, the degradation rate was stable when the degradation rate reached more than 95%. The degradation rate of methanol aqueous solution is much higher than that of methanol solution as solvent. The radiation dose rate has a certain effect on the degradation rate of TeA. The degradation effect of high dose rate on TeA is lower than that of the low dose rate, but the degradation rate is decreased with the dose rate. The result suggests thay ray irradiation has a good effect on the degradation of TeA in solution.The degradation rate of TeA in wheat under different irradiation doses was explored by gamma ray irradiation on wheat samples contaminated with TeA. The polynomial equation y=ax+b is used to fit the radiation dose, and the correlation coefficient is 0.9435. The experiments show that the gamma ray could degrade the TeA in wheat.(3) To analysis the degradation products of TeA in solution. The degradation products in aqueous solution were analyzed by the comparison of total ion current chromatogram, mass spectrometry and mass chromatogram adopting the method of LC-TOF-MS. The experiment produce four main products, which the m/z are 244.1559?244.1559?244.1556? 258.2081.This study establishes quantitative detection method of solution for TeA, and for the first time explores the 60Co gamma ray of TeA irradiation degradation, and undertakes further degradation products analysis. This research will pave the way for the future exploration of degradation and identification of TeA and other mycotoxins.