Decontamination of Vegetables and Fruit


Recent outbreaks of foodborne infection including Listeria, Salmonella and E.coli are attributed to consumption of contaminated fruit and specifically leafy vegetables. A current publication in Food Microbiology and Safety reported on comparisons of pulsed light, ultraviolet irradiation alone or in combination with washing to eliminate Salmonella. Both spot and dip inoculation were applied to simulate contamination under controlled laboratory conditions.

Pulsed light was applied at 0.3 J/cm2 in three consecutive pulses. This treatment was compared to ultraviolet irradiation at 28mW/cm2 for 2 minutes for the most extreme treatment. All treatments reduced levels of contamination by approximately three logs especially on fruit, but lettuce was more refractory to the treatments. Since UV irradiation was as effective as pulsed light and requires lower capital expenditure, this technology was recommended in combination with washing to reduce bacterial pathogens.

To achieve eradication it will be necessary to apply electron beam treatment to fruit and produce. Although effective and relatively inexpensive, the technology has yet to be shown to be consumer- acceptable. If the technology is promoted as “like an x-ray” consumers will be willing to purchase produce certified free of bacterial contamination. If regarded as an “irradiation” many consumers would prefer to risk infection.

*Huang, R. and Chen, H., Comparison of water-assisted decontamination systems of pulse light and ultraviolet for Salmonella inactivation on blueberry, tomato and lettuce. Microbiology and Safety, (2019)