Microwave-powered cold plasma treatment for improving microbiological safety of cherry tomato against Salmonella

Microwave-powered cold plasma treatment (CPT) has been investigated as a nonthermal intervention technology for improving the microbiological safety of cherry tomatoes (Solanum lycopersicum var. cerasiforme) against Salmonella (approximately 7 log CFU/tomato). Cherry tomatoes were subjected to CPT using helium (He) or a He-oxygen (O2) gas mixture for 2-10 min at 400-900 W of plasma generation power. A central composite method was applied to investigate the interactions between treatment conditions and the Salmonella reduction rate, weight loss, or temperature of the tomatoes. CPTs using He and a He-O2 gas mixture at 827 W for 9 min resulted in the greatest reduction in Salmonella numbers (3.5 ± 0.1 and 3.5 ± 0.5 log CFU/tomato, respectively) and temperature increases of 3.0 ± 0.3 and 3.5 ± 0.4 °C, respectively. He-CPT at 900 W for 10 min, determined as the optimal conditions for Salmonella inactivation in this study, did not appreciably influence the surface morphology of cherry tomatoes. While the optimal He-CPT did not effectively inhibit the growth of Salmonella on the tomatoes at 25 °C, the treatment prevented the Salmonella growth during storage at 5 °C, without affecting the tomato respiration rate (P < 0.05). These results demonstrate the potential of CPT as a postharvest technology to improve the microbiological safety of cherry tomatoes against Salmonella, without affecting their biological properties.