| Mycotoxins 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. As a method for protecting food safety, food irradiation has been an important part of the national scientific and technological support.The objective of the research is to study the degradation effects of mycotoxins by irradiating agricultural products and to testify that irradiation is practicable in controlling mycotoxins in agricultural products, thus the application area of irradiation can be expanded and food safety would be safeguarded powerfully. This research selects aflatoxin B1 and fumonisin B1 as objects, and chooses peanut and maize as the target food. Several problems are involved: (1) whether mycotoxins degrade under irradiation; (2) how much are the degradation rates; (3) whether the quality of the agricultural products after irradiation is acceptable; (4) what are the radiolysis products. All these problems are necessary to determine that irradiation is an appropriate technology to eliminate mycotoxins in agricultural products.The main projects and research results are as follows:1. The degradation effects of aflatoxin B1 and fumonisin B1 solution under irradiation was firstly investigated. The results showed that under the dose of 6kGy and the concentration of 0.1mg/L, the degradation rate of aflatoxin B1 was 96%; under the dose of 10kGy and the concentration of 0.1 mg/L, the degradation rate of fumonisin B1 was above 90%. The research demonstrated that mycotoxins can be degraded under irradiation. The degradation rate had a positive correlation with the irradiation doze and a negative correlation with the initial concentration.2. The degradation effects of mycotoxins in agricultural products and quality changes of agricultural products after irradiation were studied. Peanut and maize were inoculated with 107 of spore suspension of Aspergillus flavus and Fusarium moniliforme known to produce aflatoxin B1 and fumonisin B1. After the inoculation period, peanut and maize samples were irradiated with gamma radiation and electron beam at the doses 2, 4, 6, 8, 10kGy. The results indicated that the degradation rates of mycotoxins were positively correlated with the increase in the applied dose of gamma ray or electron beam. Under 10kGy doze ofγray, the degradation rates of peanut samples were 60.66% and 59.41% for peanut flour and peanut, respectively; the degradation rates of maize samples were 63.63% and 64.46% for maize flour and maize, respectively. The degradation rates of aflatoxin B1 with different sizes were significantly different; the conclusion of fumonisin B1 was opposite. At a dose of 10kGy, the degradation rates of peanut were 59.41% and 71.51% forγray and electron beam, respectively; the degradation rates of maize were 63.46% and 58.06% forγray and electron beam, respectively. The degradation rates of aflatoxin B1 under different rays were significantly different; the conclusion of fumonisin B1 was opposite.3. According the Chinese Standard, the largest content of aflatoxin B1 in agricultural products is 20μg/kg. So, if the content of aflatoxin B1 in peanut is 50μg/kg, it can be irradiated with the dose of 10kGy to meet the Chinese Standard. According to the recommended international standard, the largest content of the fumonisin B1 in agricultural products is 2.0mg/kg. So, if the content of fumonisin B1 in maize is 5.0mg/kg, it can be irradiated with the dose of 10kGy to meet the recommended international standard.4. The radiolysis products of aflatoxin B1 solution were preliminarily studied. 100mg/L aflatoxin B1 solution was irradiated byγray. The irradiation doses were 10kGy and 20kGy. HPLC-MS/MS had been used to analysis the molecular weights and fragments information of these radiolysis products. The results showed there were four radiolysis products in the aflatoxin B1 solution after irradiation. The molecular weights were 396,346,361,318。There is no relevant research on the irradiation degradation of mycotoxins in food in our country. In other countries, this research has just started and focused on the effects of irradiation. This research investigated the irradiation degradation rates systematically and also involved the radiolysis products, which can provide basis knowledge for the safety of irradiation food and is also significant to food safety. |
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