Inactivation of Penicillium aerosols by atmospheric positive corona discharge processing

Abstract

Microbial infection, especially from mold aerosols inside storage facilities, is an important cause of the short-term deterioration of horticultural products. As a novel non-thermal sterilization technology, atmospheric positive corona discharge (APCD) is an efficient method for introducing low-temperature plasma to inactivate pathogens in horticultural cold-storage environments. Here, APCD was investigated for the inactivation of Penicillium expansum aerosols. Scanning electron microscopy and transmission electron microscopy revealed noticeable changes in the morphology and interior of P. expansum spores on agar plates after exposure to low-temperature plasma generated by APCD. A first-order kinetics model better supported the survival curves of P. expansum aerosols exposed to low-temperature plasma than other models such as Weibull and simplified Baranyi distribution. The D-value (the time taken to achieve a 10-fold reduction in fungal spores in first-order kinetics) varied from 70 to 204min at various conditions of discharge-power (0.65–1.65VA) and air-flow (300–900L/h). A model was constructed using response surface methodology to describe the relationship between sterilization efficiency in terms of the D-value and the key parameters (discharge-power and air-flow) under conditions of temperature and relative humidity at 3±1°C and 90±5%. The kinetics description of the inactivation of P. expansum aerosols will be instructive for the potential application of APCD in horticultural cold storage.