Effectiveness of UV Light as A Means to Reduce Salmonella Contamination on Tomatoes and Food Contact Surfaces

Summary

While Salmonella contaminated fresh produce has been linked to multiple foodborne illness outbreaks, fresh produce receives little microbial intervention other than washing. An alternative strategy to reduce the pathogenic bacterial levels on fresh produce is to use UV light at a wavelength of 200-280 nm. However, repair of bacterial injury by photoreactivation with visible light is a concern.

Situation

This study evaluated the effectiveness of UV-C light (254 nm) in reducing Salmonella contamination on tomatoes under different UV-C treatments and to determine if subsequent exposure to visible light would result in photoreactivation of injured Salmonella. Decontamination of fresh produce by UV light treatments could be a useful pathogen intervention method for use by small produce operations.

Response

Tomatoes were inoculated with Salmonella and air-dried before exposing to UV-C light at different doses (0, 1, 2, 4, and 6 mJ/sq cm) at a distance of 60 cm. After the UV-C treatments, the tomatoes were exposed to fluorescent light at 0, 0.85, 4.26, and 20.42 J/sq cm. Treated tomatoes were sampled to enumerate surviving Salmonella.

Impact

UV-C dosages of 1 and 2 mJ/sq cm reduced the Salmonella population by 99% (2 logs). Salmonella populations were reduced by >99.7% (>2.56 logs) when the tomatoes were treated with 4 and 6 mJ/sq cm. There was no evidence of injury repair by photoreactivation by visible light treatments. Use of UV-C light may be a promising means to reduce Salmonella contamination on fresh tomatoes.

State Issue

Food Safety

Details

• Year: 2013
• Geographic Scope: International
• County: Clarke
• Program Areas:
  • Agriculture & Natural Resources