## 3 Results and Discussion  
### Effect of ACP Treatment on Deoxynivalenol Degradation on Barley Grains  
A significant (\(p<0.05\)) decline in the DON concentrations on barley grains by ACP treatment was generally observed (Figure 2). A significant decrease in DON concentration within 6 min ACP treatment was observed, but thereafter, the reduction rate was not significant (\(p\geq 0.05\)). The degradation rates after 6 and 10 min ACP treatments were 48.9% and 54.4%, respectively. The generated ozone in plasma probably had a significant effect on DON degradation [23,24]. In general, for a long treatment time, with the production of more reactive species, an increase in the DON degradation rate should be observed. However, during extended treatment times, the generated ozone can be depleted by other reactive species by the following destruction cycles (Equations (1)-(9)) [25,26]. \[O_{3}+HO_{2}\to 2O_{2}+`OH \tag{1}\]  
\[`OH+O_{3}\to HO_{2}+O_{2} \tag{2}\]  
\[`H+O_{3}\to`OH+O_{2} \tag{3}\]  
\[`H+O_{3}\to HO_{2}+`O \tag{4}\]  
Figure 2: Effect of ACP treatment on (**A**) relative deoxynivalenol reduction % and (**B**) deoxynivalenol concentration (ug/mL) on barley. Data are shown as least square means \(\pm\) standard deviations. Values with different letters in each figure are significantly different (\(p<0.05\), \(n\)=3). \[2O_{3}\to 3O_{2} \tag{5}\] \[\dot{}O+O_{3}\to O_{2}+O_{2}\] (6) \[\dot{}N+O_{3}\to NO+O_{2}\] (7) \[NO+O_{3}\to NO_{2}+O_{2}\] (8) \[NO_{2}+O_{3}\to NO_{3}+O_{2} \tag{9}\]  
where the reactive species \(HO_{2}^{\cdot}\), \(OH\), \(H\), \(O\), \(N\), \(NO\), \(NO_{2}\) are hydroperxyl radical, hydroxyl radical, atomic hydrogen radical, atomic oxygen radical, atomic nitrogen radical, nitrogen oxide, and nitrogen dioxide radical, respectively. The constant concentration of ozone in the environment may be attributed to the simultaneous ozone generation and depletion, due to its reactions with other reactive species in longer treatment times. This could be the possible reason for small increases in degradation rates of DON after 6 min ACP treatment. The constant concentration of ozone in longer treatment times was observed in previous studies [27; 28]. [PERSON] et al. [27] reported no further increase in ozone concentration after 180 s of in-package cold plasma treatment, attributed to the quenching of ozone by reactions with N\({}_{2}\), water, and/or new reactive species formed in plasma during long treatment times. It is worth mentioning that the ozone generation and depletion reactions are complicated and are dependent on various factors, i.e., not only treatment time, but also temperature, gas composition, voltage, etc. [26]. [PERSON] et al. [29] reported 22.5 and 34.6% degradation in DON level on raw and germinating barley, respectively, by using plasma-activated water (PAW), treated for 5 min. They did not observe a significant (\(p\geq 0.05\)) decline in DON concentration in the treated samples between 5 and 20 min using PAW. In our recent study on pure DON on a cover-glass, formation of C = O group and epoxy ring in the ACP treated sample was observed, which could be due to the reaction between ROS with DON [30]. We achieved a degradation level of 39.8% in pure DON after 15 min ACP on cover-glass, in comparison to the 48.9% degradation of DON, inoculated on barley after ACP treatment for 6 min. This highlights the importance of the type and nature of the substrate on DON degradation. [PERSON] et al. [31] applied 80 \({}^{\circ}\)C heat to DON on barley, and the concentration was reduced from 18.4 to 14.7 ug/g DON barley, 1 day after the thermal treatment. DON concentration was reduced by 58%, 5 days after the treatment. [PERSON] et al. [26] reported the use of ozone treatment to wheat samples, to reduce DON concentration. Treatment with 75 mg/L ozone for 90 min reduced DON concentration by 53.5% on wheat kernels. [PERSON] et al. [24] reduced DON concentration by 32% after 240 min ozone treatment.