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United States Department of Agriculture

Agricultural Research Service

Research Project: MICROBIAL FOOD SAFETY OF FRESH AND FRESH-CUT PRODUCE Title: Enhanced salmonella reduction on tomatoes washed in chlorinated water with wash aid T-128

Authors
item Yang, Yang -
item Luo, Yaguang
item Nou, Xiangwu
item Millner, Patricia
item Shelton, Daniel
item Feng, Hao -

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: March 21, 2011
Publication Date: April 27, 2011
Citation: Yang, Y., Luo, Y., Nou, X., Millner, P.D., Shelton, D.R., Feng, H. 2011. Enhanced salmonella reduction on tomatoes washed in chlorinated water with wash aid T-128. BARC Poster Day.

Technical Abstract: Chlorine is widely used by the fresh and fresh-cut produce industries to reduce microbial populations and to prevent potential pathogen cross contamination during produce washing. However, the organic materials released from produce quickly react with chlorine and degrade its efficacy for pathogen inactivation in wash water. A novel wash aid, T-128, was evaluated for its capacity to enhance the efficacy of chlorine solution against Salmonella in the presence of high organic load. Increasing levels of tomato juice were added to chlorinated wash solutions to simulate free chlorine depletion during tomato washing. Salmonella enterica sv. Thompson was inoculated into the wash solutions in the presence or absence of T-128 and Salmonella inactivation was determined following 30 sec exposure. Survival of Salmonella was reduced significantly in chlorinated water containing T-128, even when free chlorine in wash water dropped to levels approaching the detection limit. The effect of T-128 was also evaluated using Salmonella cells inoculated on tomatoes. Contaminated tomatoes were washed in chlorinated water with or without T-128 for 2 min and Salmonella survivals on smooth tomato surface and on stem scars were examined. Salmonella was not recovered from tomato surface following treatment regardless of the use of T-128. However, Salmonella was detected on stem scars and the addition of T-128 to chlorine solution further reduced Salmonella populations in stem scar tissue by 1 log10 unit compared to control (chlorine solution alone). The efficacy of T-128 for reducing cross contamination was evaluated by washing inoculated tomatoes with non-inoculated tomatoes. No cross contamination was observed when free chlorine was 10 ppm or above with or without T-128. When washed in solution containing 5 ppm free chlorine, cross contamination was prevented in the presence of T-128 but not in the absence of T-128. Cross contamination by Salmonella occurred when tomatoes were washed in chlorine solution containing 0.2 ppm free chlorine with or without T-128. However, Salmonella populations on non-inoculated tomatoes were 1 log10 unit lower when T-128 was added. These results show that T-128 enhanced the efficacy of chlorine in killing Salmonella and preventing cross-contamination, especially at low chlorine concentrations, and therefore shows great potential for use by fresh produce processors to improve the safety of fresh-cut produce.

Last Modified: 10/25/2014
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