Research On Technology Of Irradiation Degradation Of Ochratoxin A In Maize

The mycotoxin in agricultural products has concerned us more and more as its great harm for the health of humans and animals. The technology of food irradiation, a boom technology in 20th century, is proved to be a measure of preservation with high efficiency and no pollution after long-term researches and applications. Food irradiation could be an important technology to deal with mycotoxin pollution in agriculture products in order to ensure safety, there is no add-in of chemicals in the process of food irradiation, so this technology could not cause pollution repeated, what's more, the irradiation is carried out under normal pressure and temperature which can bring out high efficiency.The effect ofγ-irradiation on degradation of Ochratoxin A was researched on the basis of products structure and their toxicity in order to provide reference for application of irradiation in degradation of mycotoxin, which could control OTA pollution in agricultural products. OTA was taken as an example of mycotoxin, then the effects ofγ-irradiation on degradation of Ochratoxin A in aqueous solution, products structure and toxicity in aqueous solution, the effects ofγ-irradiation on degradation of Ochratoxin A in maize, products structure and toxicity in maize, the change of maize quality and the toxicity of products were evaluated. The main research results are followed:(1) OTA in aqueous solution was irradiated byγ-rays to evaluate the irradiation degradation effects. The standard aqueous solution of OTA was applied to determine the linear relationship and detection limit of HPLC, with the external standard method for quantitative analysis, which was used to investigate the effects of absorbed doses on the degradation of OTA in aqueous solution. The results showed that the degradation rate of OTA in aqueous solution increases with the absorbed dose in certain range with no proportional. The degradation rate changed with irradiation doses by polynomial equation to fitting: y=ax~2+bx+c. The degradation rate reached the maximum, 90%, at 4 kGy, and then it tended to be stable. What's more, the degradation rate was higher with lower concentration of OTA in aqueous solution. As a result, 60Coγ-rays could have good effect on the degradation of OTA in aqueous solution with lower absorbed dose.Five main radiolysis products of OTA degradation were analyzed and their toxicity was also evaluated. LC/TOF MS (Liquid -Chromatography-Quadrupole-Time-of-Flight Mass Spectrometry) was applied for the analysis of five radiolysis products. The results showed that one product was OTA hydrolysate, three products were OTA analogs, and the product left hadn't been reported. The search results in related toxicity databases indicated that there was only one product with toxicity much lower than OTA and other four products no toxicity. It was speculated that the toxicity of radiolysis products of OTA degradation could be ignored.To evaluate the effects ofγ-irradiation on degradation of OTA in maize, maize samples contaminated with OTA was irradiated byγray firstly, while content of OTA in maize was 71μg/kg, then the quantity of OTA in samples was assayed with HPLC which was compared at different doses, and the nutritional components were also detected. The result showed that he content of OTA in maize decreased significantly, and the rate of degradation of OTA could reach 50% at the dose of 10kGy. The nutritional components were not destroyed byγ-irradiation.γ-irradiation could degrade OTA in maize with fine rate of degradation and not decrease the quality of maize.Considered that the products structure of OTA irradiated was difficult to analyze for complicated components in maize, toxicology experiments were arranged to determine the toxicity of OTA and its products after irradiation. Results: OTA could affect growing status of mice such as the augment of body weight and the rate of food utilization, compared with that the radiolysis products of OTA degradation brought out no effects. OTA could destroy blood platelet and lymphocyte of mice, increase AST, GLU, BUN in mice serum and decrease LDH. Some viscera of mice could be shattered by OTA such as liver, kidney and lung, except spleen. But the radiolysis products of OTA degradation have no effects on all the viscera. It was indicated that OTA has toxicity on mice and the radiolysis products of OTA degradation has no such toxicity. Therefore, OTA could be irradiated with high efficiency and no toxicity.Foreign researches on OTA irradiation are just primary currently, which focus only on the rate of OTA irradiation, and there are no related studies on the products structure of OTA irradiated and their toxicity all over the world. The effects and disciplinarian ofγ-irradiation on degradation of Ochratoxin A were explored in our research with detail, as well as the analysis of these products and toxicology experiments, which can provide academic foundation for irradiation of other mycotoxin.