A study of mango wash water finds that chlorine and peracetic acid are more effective than chlorine dioxide in eliminating salmonella from packinghouse dump tanks.

The research by Mary Anne Amalaradjou, assistant professor of animal science at the University of Connecticut in Storrs, is funded by the National Mango Board and the Center for Produce Safety. Amalaradjou is examining the impact of disinfectants on salmonella transfer.

Mangoes come in contact with water three times in a packinghouse. The findings so far concern the first of these, a brief wash in a dump tank. Amalaradjou plans to complete the remaining steps, hot-water treatment and hydrocooling, in 2016.

“With chlorine and (peracetic acid at the levels used), we don’t recover any salmonella from the water or mangoes or the dump tank,” she said in a news release. “With chlorine dioxide up until 30 seconds, it’s still positive (for salmonella). But after that it becomes negative.”

The two-year study is expected to add information to the National Mango Board’s manual of best management practices. “I’m trying to figure out how effective the current practices are at controlling salmonella and what can be done to make them better,” Amalaradjou said in the release.

The National Mango Board flew her to a Puerto Rico packinghouse to see the steps the fruit passes through from arrival until it is shipped. That helped her replicate the processes on a smaller scale using 30-gallon containers in her laboratory.

Amalaradjou also was able to collect water samples so she could simulate the same ratios of soil and organic matter in her lab.

Organic matter is an issue, especially with chlorine and chlorine dioxide, because in large enough volumes it can significantly reduce their effectiveness. Based on her packinghouse water sample analysis, Amalaradjou used mango wash water that contains latex, the main organic matter found in mango dump tank water, as well as clay-loam soil to simulate organic contamination.

The board also continues to ship her freshly harvested fruit that has not been through a packinghouse.

Manuel Michel, executive director of the National Mango Board, said the mango industry funded the project because it is always seeking more effective water disinfectants.

“This study will generate new knowledge and should provide science-based results that mango operations can incorporate right away,” Michel said in the release. “Food safety and quality are top priorities for the mango industry, and the information generated from this study will help improve the best management practices in the areas of washing and postharvest handling of mangoes.”