Principal antifungal factors and underlying mechanisms of dielectric barrier discharge plasma against Penicillium expansum spores as well as its application in kiwi-fruit juice
Yafei Zhai, Jiaqi Sun, Shuo Ye, Yuhao Wang, Jiali Tian, Yanhong Bai, Qisen Xiang, Ruiling Shen
Abstract
The objective of this work was to investigate the main antifungal factors and mechanisms of dielectric barrier discharge (DBD) plasma against Penicillium expansum spores. The application in kiwi-fruit juice was also studied. The results showed that 240 s was adequate for an about 6.0 log10 reduction of survival spores in kiwi-fruit juice after plasma treatment at 18 kV. DBD plasma treatment resulted in slight changes in pH, total phenolics, and color parameters of kiwi-fruit juice, but did not affect the total soluble solid and vitamin C contents. Among the longer-lived species generated by DBD plasma, NO2− was demonstrated to be related with the inactivation of P. expansum spores, but not considered as the important agent. Additionally, short-lived species (such as ∙OH, O2∙−, and 1O2) were confirmed to exist in the plasma-water system by electron spin resonance spectroscopy. Thereinto, O2∙− and 1O2 contributed the most to the inactivation. Both species caused the morphologic alteration, membrane disruption, intracellular substance leakage, and DNA damage of spores. In conclusion, DBD plasma can effectively inactivate P. expansum spores in kiwi-fruit juice, which is mainly due to the disruption of cell membrane and DNA damage induced by O2∙− and 1O2 derived from DBD plasma.