ARS | Publication request: Efficacy of hot water surface decontamination of green tomatoes artificially inoculated with Salmonella Poona

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 18, 2010
Publication Date: July 17, 2010
Citation: Annous,B. 2010. Efficacy of hot water surface decontamination of green tomatoes artificially inoculated with Salmonella Poona [abstract]. IFT. Chicago, Illinois. p.1.

Technical Abstract: Numerous foodborne outbreaks have been associated with the consumption of fresh tomatoes contaminated with Salmonella. Commercial washing processes for tomatoes are limited in their ability to inactivate and/or remove this human pathogen. The objective of this study was to develop and validate a hot water surface pasteurization process capable of decontaminating artificially inoculated fresh tomatoes. Fresh green tomatoes, dip inoculated with Salmonella Poona RM 2350 or to a final cell concentration of ca. 5 log CFU/gm were stored at 4 and 20C for up to 24 h prior to processing. Six inoculated tomatoes were treated for 3.5 min in 70C water or 20 ppm chlorine solution, and individual tomatoes was blended in peptone water (1:1) for 1 min. Enumeration of non-injured cells was done by plating on the selective media XLT-4 incubated at 35C overnight. Injured cells were recovered by plating on non-selective media TSA and incubating at 35C for 2 h and then plates were overlaid with XLT-4 and were incubated at 35C overnight. Hot water treatment resulted in up to 6 logs reduction in S. Poona populations as compared to 1 log reduction using 20 ppm chlorine treatment. Hot water treated tomatoes that were stored at 20C for 5 days showed normal maturation process with no obvious visual injury. Storage of untreated inoculated tomatoes at 13, 20, and 30C for up to 6 days post inoculation caused a significant (p<0.05) increase in S. Poona populations (up to 3 log CFU/gm) as compared to storage at 4C. These results indicate that surface pasteurization will enhance the microbiological safety of tomatoes with no adverse effect on maturation process, and will extend the shelf life of this commodity as well. Storage data indicated that tomatoes should be refrigerated as soon as possible following harvesting to suppress the growth of any possible contaminant.