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Modeling of Patulin Degradation in Apple Based Beverages by Multiple Wavelengths of Ultraviolet-C Irradiation

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Title: Modeling of Patulin Degradation in Apple Based Beverages by Multiple Wavelengths of Ultraviolet-C Irradiation
Author: Zhu, Yan
Department: Department of Food Science
Program: Food Science
Advisor: Warriner, Keith
Abstract: The mycotoxin patulin is a secondary metabolite produced by a range of molds and is commonly associated with apple juice derived from spoiled fruit. The study investigated the application of UV-C radiation (200-300 nm) to degrade patulin in apple juice/cider and inactivate patulin- producing molds. The degradation of patulin irradiated at UV 254 nm followed first-order kinetics the rate of which was influenced by the fluence rate, sample thickness and absorption coefficient of the sample. The UV fluence required at 254 nm to support 90 % degradation of patulin was 84.3 mJ∙cm-2 which compares to 19.6 and 55.0 mJ∙cm-2 when wavelengths of 222 nm and 282 nm were applied respectively. When all three UV-C wavelengths were applied simultaneously the dose required to decrease patulin by 90 % was 36.6 mJ∙cm-2. The higher degradation rates at 222 nm was by virtue of the higher photon energy compared to the other wavelengths tested. At 222 nm there was a significant change in juice color but this did not impact on the overall sensory characteristics. By using Saccharomyces cerevisiae and Drosophila melanogaster toxicity assays the photoproducts generated by the UV degradation of patulin were found to be less toxic compared to the native mycotoxin. Further work demonstrated that the UV-C fluence applied to support a 3 log reduction of the Penicillium expansum spore levels in apple juice resulted in > 90 % patulin degradation. The inactivation of Penicillium by UV-C followed tri-phasic kinetics with distinct shoulders and tailing effects. In the course of storage at 4 ºC, the UV treated apple juice inoculated with Penicillin accumulated significantly less patulin compared to non-UV irradiated controls. In conclusion, the study has modelled the degradation kinetics of patulin in apple juice and illustrated that molds surviving UV treatment have a reduced capacity to produce the mycotoxin.
Date: 2014-11
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