Tomatoes and salmonella poisoning made the news again and with them came some startling scientific revelations. An article written by Lauran Neergaard (AP Medical Writer) and released/published on June 23, 2008 revealed new information about how tomatoes may possibly trap, carry, and incubate salmonella.
“WASHINGTON – Pick a tomato in the blazing sun and plunge it straight into cold water. If that happened on the way to market, it might be contaminated. Too big of a temperature difference can make a tomato literally suck water inside the fruit through the scar where its stem used to be. If salmonella happens to be lurking on the skin, that’s one way it can penetrate and, if the tomato isn’t eaten right away, have time to multiply.
That doesn’t mean people shouldn’t wash their tomatoes â€” they should, just probably not in cold water.
But as the Food and Drug Administration investigates the nation’s outbreak of salmonella from tomatoes, the example shows the farm isn’t the only place contamination can occur â€” and checking things like water quality and temperature control in packing houses and other supply stops is one key to safety.”
This raises the question of what sorts of water quality parameters packing houses should monitor on a regular basis.
Sanitizer and Disinfectant Levels — If the water used to wash, rinse and cleanse the tomatoes contains enough sanitizer, then theoretically no salmonella or other forms of bacterialogical contaminants could survive in the water. No contaminants in the water means no contaminants that a tomato could ‘suck up’ if submerged in cold water.
“Water is an automatic first suspect. Was clean water used to irrigate, mix pesticides sprayed on crops, wash down harvest and processing equipment, and wash field workers’ hands?
Then in packing houses, tomatoes often go straight into a dump tank, flumes of chlorinated water for a first wash. To guard against salmonella washed into the water in turn being sucked into the tomatoes, producers often keep wash-water 10 degrees warmer than the incoming crop, says food-safety scientist Keith Schneider of the University of Florida, also part of FDA’s tomato initiative.
Beyond packing houses, the industry points to cases where suppliers were shipped unwashed, warm tomatoes and dunked them in ice-water baths to firm them for further processing.
Another question: How often does the water have to be changed? Dirt, leaves and other sediment reduce the chlorine’s effectiveness.”
Produce handlers and packing houses could reduce the chances of accidentally passing fresh produce through improperly disinfected wash water by implementing test procedures and protocols which make use of simple, inexpensive chlorine test strips such as SenSafeTM Free Chlorine Water Check, a product approved by the USEPA and by several states for drinking water compliance monitoring.
The manufacturer of this product also has dip-n-read test strips capable of detecting chlorine concentrations as high as 2,000ppm and as low as 0.005ppm.