Effects of Cold Plasma Fumigation (CPF) Treatments on the Inactivation of Escherichia coli on Food Contact Surfaces and Fresh Produce.

Abstract

Cold plasma fumigation (CPF) is a novel approach that enables indirect sanitization and offers high scalability potential for fresh produce processing applications. In this study, two configurations of plasma reactors, rod-to-mesh dielectric barrier discharge (DBD) and rod-to-clamp plasma jet reactors, were used to generate gas plasma by activating compressed air at relatively low voltages. The CPF practices were evaluated for their efficacy on the inactivation of E. coli strain TVS355 on multiple food contact surfaces (stainless steel and glass) and fresh produce (strawberry and blueberry). The samples were spot inoculated with E. coli and placed inside an enclosure for plasma treatment at different combinations of AC voltages (150 V and 200 V) and power modulation frequencies (500 and 1000 Hz) for 10, 15, and 20 min. With the DBD reactor, CPF treatment (200 V and 1000 Hz) achieved the most significant reduction of 4.43 log CFU/coupon on stainless steel coupons in 10 min and 4.26 log CFU/coupon on glass coupons in 20 min. With the jet reactor, CPF treatment (150 V and 1000 Hz) for 15 min reduced bacterial levels by 4.28 log CFU/coupon on stainless steel coupons, and CPF treatment (150 V and 500 Hz) for 15 min reduced bacterial levels by 2.59 log CFU/coupon on glass coupons. CPF treatment (150 V, 1000 Hz, 20 min) using the jet reactor reduced bacterial populations by 1.13 and 1.12 log CFU/produce on strawberries and blueberries, respectively. In conclusion, CPF effectively reduced bacterial loads on fresh produce and food contact surfaces while minimizing power consumption.