| In this study, the distribution of DON in the wheat kernel and the effect of exposure time to ozone on DON detoxification were investigated. Besides, to provide theoretical and practical evidences for possible application of this method, not only the effect of ozonation on wheat flour quality and nutrition was evaluated, but also the safety of deoxynivalenol-contaminated wheat treated by ozone was studied by vivo toxicity test.Firstly, the degradation of DON by ozone in wheat were studied. A high concentration of toxin was found in the outer part of the kernel, and DON was injected from the outside to the inside. The degradation rates of DON were 26.4%, 39.2%, 53.5%, 54.4% and 56.1% after the samples were exposed to 75 mg/L ozone for 30, 60, 90, 120 and 150 min, respectively. DON levels were significantly decreased in bran and shorts(P<0.05), whereas degradation rate was not significant different among all flour fractions(P>0.05). Ozone gas significantly affected the external part of wheat grain compared with that in the endosperm when eliminating DON.Secondly, the effect of ozonation on wheat flour quality were researched. After 90 min of 75 mg/L ozone treatment, no significant differences were found in protein content, starch content, fatty acid value and amino acid content(P>0.05). The ozone-treated samples exhibited higher brightness and whiteness, as well as lower yellowness. Meanwhile, viscosity properties of wheat flour showed significant decrease in peak viscosity, low viscosity, final viscosity and breakdown(P<0.05). Moreover, higher water absorption and tenacity, as well as lower extensibility were detected by the results of consistmeter alveograph.Furthermore, the effect of ozonation on the qualities of starch and protein were tested. After 90 min of 75 mg/L ozone treatment, no significant differences were found in carbonyl content, carboxyl content, and swelling power of ozone-treated samples(P>0.05). And no obvious changes were found in the carbohydrate distribution of starches isolated from wheat flour(P>0.05). However, with the increasing of ozone treatment time, the damaged starch content increased by 9.93%. SEM images showed that surface of the starch granules was more crude after ozone treatment. In addition, gluten index increased by 19.7%, while the content of wet gluten and free sulfhydryl groups decreased by 10.7% and 20.4%, respectively. Network structure of dough was strengthened according to the SEM images.Last but not least, the safety of DON degradation by ozone were analysed. In the 51-day administration experiment, no remarkable changes were observed in the general appearance of the mice, and all of the mice survived until the scheduled necropsy. The results of subchronic toxicity indicated that mice fed on deoxynivalenol-contaminated wheat alone had significantly decreased body weight gain, thymus and spleen weights, ratios of liver, thymus and spleen to body weight, blood indices(RBC, WBC, HGB), and pro-inflammatory cytokines(IL-6, TNF-α), while showing a significant increase in ALT, AST, Scr and BUN levels(P<0.05). Histopathological examination indicated that DON elicited some degree of toxicity on the liver, kidney and thymus tissue. Mice fed on deoxynivalenol-contaminated wheat treated by ozone showed significant beneficial health effects compared with mice fed on deoxynivalenol-contaminated wheat without treatment. All of the results suggested that the deleterious effects of DON could be highly reduced by ozone, and ozone itself shows minor toxic effects on animals in this process. |
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