Inactivation of human pathogens and spoilage bacteria on the surface and internalized within fresh produce by using a combination of ultraviolet light and hydrogen peroxide
2008
Hadjok, C. | Mittal, G.S. | Warriner, K.
To evaluate the efficacy of ultraviolet (UV) light (254 nm) combined with hydrogen peroxide (H₂O₂) to inactivate bacteria on and within fresh produce. The produce was steep inoculated in bacterial cell suspension followed by vacuum infiltration. The inoculated samples were sprayed with H₂O₂ under constant UV illumination. The log count reduction (LCR) of Salmonella on and within lettuce was dependent on the H₂O₂ concentration, temperature and treatment time with UV intensity being less significant. By using the optimized parameters (1·5% H₂O₂ at 50°C, UV dose of 37·8 mJ cm⁻²), the surface Salmonella were reduced by 4·12 ± 0·45 and internal counts by 2·84 ± 0·34 log CFU, which was significantly higher compared with H₂O₂ or UV alone. Higher LCR of Escherichia coli O157:H7, Pectobacterium carotovora, Pseudomonas fluorescens and Salmonella were achieved on leafy vegetables compared with produce, such as cauliflower. In all cases, the surface LCR were significantly higher compared with the samples treated with 200 ppm hypochlorite. UV-H₂O₂-treated lettuce did not develop brown discolouration during storage but growth of residual survivors occurred with samples held at 25°C. UV-H₂O₂ reduce the bacterial populations on and within fresh produce without affecting the shelf-life stability. UV-H₂O₂ represent an alternative to hypochlorite washes to decontaminate fresh produce.
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