Inactivation of Enterobacter aerogenes on the surfaces of fresh-cut purple lettuce, kale, and baby spinach leaves using plasma activated mist (PAM)

• Published in: Innovative food science & emerging technologies Vol. 74; p. 102868
• Main Authors: Tan, Juzhong, Karwe, Mukund V.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2021
• Subjects: Enterobacter aerogenes; Plasma activated mist; Vegetable leaves; Plasma activated mist; Vegetable leaves; Enterobacter aerogenes
• ISSN: 1466-8564; 1878-5522
• DOI: 10.1016/j.ifset.2021.102868

Dielectric barrier discharge plasma-activated mist (PAM) is a surface treatment that has been shown to have antimicrobial effects on microorganisms attached to food contact surfaces. In this study, tryptic soy agar, purple lettuce, kale, and baby spinach leaves, were surface-inoculated with Enterobacter aerogenes inoculum (4 × 107 CFU/ml) and held for 30 min at room temperature (25 °C), then subsequently exposed to PAM in an enclosure (0.04 m3) from 5 to 20 min. Reductions ranging from 3.8 ± 0.1 log CFU/plate to 5.6 ± 0.3 log CFU/plate were observed on agar plates after exposure to PAM for 5 to 20 min. The leaves were either dip-inoculated or spot-inoculated. Extending PAM treatment time from 5 to 20 min increased microbial reduction on dip-inoculated leaves from 0.4 ± 0.2, 0.8 ± 0.1, and 0.9 ± 0.1 log CFU/g to 0.9 ± 0.1, 1.3 ± 0.1, and 2.0 ± 0.2 log CFU/g for purple lettuce, kale, and baby spinach leaves, respectively, and similar bacterial inactivations were observed on spot-inoculated leaves. •Plasma activated mist (PAM) was more effective against E. aerogenes attached to smooth surfaces than uneven surfaces.•Twenty minutes exposure to PAM reduced the concentration of E. aerogenes on agar plate by ~5.5 log CFU/plate.•Twenty minutes exposure to PAM reduced the concentration of E. aerogenes on leafy greens by ~2.0 log CFU/leaf.