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Mycotoxin degradation in food and feed grains by atmospheric cold plasma technology
- Author / Creator
- Feizollahi, Ehsan
Contamination of grains with mycotoxins causes quality loss and hence considerable financial loss to the grain industry. Several mycotoxins are resistant to high temperatures and the elimination of them from grains is a challenging task. Atmospheric cold plasma (ACP) is an emerging non-thermal technology, that has attracted attention due to its mycotoxin degradation potential. The overall objective of this research was to assess the efficacy of different ACP systems including dielectric barrier discharge (DBD), plasma jet, and bubble spark discharge (BSD) to degrade selected mycotoxins, i.e., deoxynivalenol (DON) and zearalenone (ZEA) in their pure form and on grains.
In the first study, the degradation of DON mycotoxin by DBD-ACP and sequential treatment with heat and light emitting diode (LED) was tested. The ACP treatment was more effective when DON was in solution form compared to dry state. There were major changes in DON functional groups after ACP treatment. The LED treatment using light pulses with 395 nm wavelength reduced DON content, however this treatment was not as effective as ACP treatment. There was no synergistic DON degradation effect when ACP was used in sequential combination with thermal or LED treatment. In the second study, DON was spiked on barley (Hordeum vulgare) grains and the efficacy of ACP on the degradation of DON and selected barley quality parameters was investigated. The results from optical emission spectroscopy (OES) proved the presence of reactive oxygen and nitrogen species (RONS) and N2 spectra were dominant. Ozone was the most prevalent reactive species present followed by nitrous oxides and hydrogen peroxide. The ACP was able to significantly reduce DON content in a short period of time. Elevating the relative humidity (RH) of the surrounding air, post-treatment storage of barley grains, and increasing the moisture content of barley did not impact the DON degradation efficacy of ACP. Steeping of barley grains prior to ACP treatment significantly increased the DON degradation rate by ACP treatment. No significant differences were observed for the tested quality parameters of barley i.e., protein, beta-glucan, and moisture content, in comparison with control samples.
The third study focused on the impact of selected product and process factors on ZEA degradation using two technologies i.e., jet ACP and DBD-ACP. In comparison to DON, ZEA was more sensitive to ACP treatment. Type of product (barley grains, canola grains, and canola meal) affected the ACP efficacy and the presence of oxygen in the carrier gas to produce ACP significantly increased the ZEA degradation by ACP treatment. Type of gas mixtures (100% N2, 90% N2+ 10% O2, 80% N2+ 20% O2, air) did not influence ZEA degradation by 3 min DBD-ACP treatment. Direct jet-ACP with higher UV intensity had better ZEA degradation efficacy compared to indirect jet-ACP with zero UV intensity. Jet-ACP treatment with 85% Ar+15%O2 resulted in the highest degradation of ZEA compared to 75% Ar+25% N2 and 100% Ar. The results suggested the contribution of factors other than the assessed RONS, such as high energy electrons and free radicals in ZEA degradation.
Degradation mechanisms of DON by plasma activated water (PAW) treatment of naturally contaminated barley (NIB) grains during steeping was investigated in the fourth study. High-performance liquid chromatography ultraviolet mass spectrometry results indicated twelve major degradation products of DON after ACP treatment and their chemical formulae were determined. Oxidation was probably the main degradation mechanism of DON by ACP treatment. PAW treatment significantly reduced DON content and using PAW in indirect mode increased β-amylase activity and germinated acrospire’s percentage compared to control. In the last study, the potential of using PAW bubbles produced from selected ACP generation methods on F. graminearum inactivation during barley steeping was investigated. BSD-ACP produced more potent PAW with high concentrations of RONS compared to continuous jet-ACP. The results from plating and qPCR technique showed that the PAW bubble treatment did not have a significant impact on natural pathogens and F. graminearum inactivation on NIB grains.
This research demonstrated the efficacy of ACP treatment on ZEA and DON degradation. The fundamental information gained from this research has set the stage for further research and development and implementation of the ACP systems in commercial applications, specifically in the barley malting industry for mycotoxin degradation and germination improvement.
- Graduation date
- Spring 2023
- Type of Item
- Doctor of Philosophy
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