Effect of Plasma-Activated Water Bubbles on Fusarium graminearum, Deoxynivalenol, and Germination of Naturally Infected Barley during Steeping

Contamination of barley by deoxynivalenol (DON), a mycotoxin produced by Fusarium graminearum, causes considerable financial loss to the grain and malting industries. In this study, two atmospheric cold plasma (ACP) reactors were used to produce plasma-activated water (PAW) bubbles. The potential of PAW bubbles for the steeping of naturally infected barley (NIB) during the malting process was investigated. The PAW bubbles produced by treating water for 30 min using a bubble spark discharge (BSD) at low temperature resulted in the greatest concentration of oxygen-nitrogen reactive species (RONS). This treatment resulted in 57.3% DON degradation compared with 36.9% in the control sample; however, the same treatment reduced germination significantly (p < 0.05). Direct BSD ACP treatment for 20 min at low temperature and indirect treatment for 30 min increased the percentage of germinated rootlets of the seedlings compared with the control. Considering both the DON reduction and germination improvement of barley seeds, continuous jet ACP treatment for 30 min performed better than the other treatments used in this study. At higher temperature of PAW bubbles, the concentration of RONS was significantly (p < 0.05) reduced. Based on quantitative polymerase chain reaction (qPCR) analysis and fungal culture tests, the PAW bubble treatment did not significantly reduce infection of NIB. Nonetheless, this study provides useful information for the malting industry for PAW treatment optimization and its use in barley steeping for DON reduction and germination improvement.

Automated summary

This study investigated the potential of plasma-activated water (PAW) bubbles for the steeping of naturally infected barley (NIB) during the malting process. The PAW bubbles produced by bubble spark discharge (BSD) treatment at low temperature resulted in the greatest concentration of oxygen-nitrogen reactive species (RONS) and achieved 57.3% degradation of deoxynivalenol (DON). However, this treatment significantly reduced germination. Continuous jet atmospheric cold plasma (ACP) treatment performed better in terms of both DON reduction and germination improvement. Higher temperature of PAW bubbles significantly reduced the concentration of RONS. The PAW bubble treatment did not significantly reduce infection of NIB according to quantitative polymerase chain reaction (qPCR) analysis and fungal culture tests.