Inactivation mechanism of Alternaria alternata by dielectric barrier discharge plasma and its quality control on fresh wolfberries

Fresh wolfberry is a super fruit with excellent nutritive and medicinal values, but highly perishable and difficult to store. In this research, dielectric barrier discharge plasma (DBD) was used to control the spoilage and mycotoxin of Alternaria alternata (A. alternata), which frequently and heavily contaminated fresh wolfberries. Results showed that DBD treatment could inactivate A. alternata with a maximum reduction of 2.26 log CFU/mL (700V,480s). Its spore inactivation behavior most fitted the Log-logistic model (R2 > 0.993). DBD disrupted A. alternata cell membrane integrity, oxidized membrane-associated substances and increased membrane permeability. The reactive oxygen species produced by DBD caused the accumulation of reactive oxygen metabolites in the spores and the inhibition of antioxidant enzyme activity. The average content of four mycotoxins on wolfberries could be reduced by 62.84% after the 60s treatment and storage for 6 days, while the decay rate decreased by 30.66%, and the firmness, TSS and DPPH free radical scavenging increased by 11.07%, 5.88% and 19.20%, respectively. Therefore, DBD could be used as a new technology to inactivate A. alternata, reduce its mycotoxin, and improve agricultural product quality.