Over the last few weeks we've been hearing about salmonella in our tomatoes. Here's some more news that's disconcerting. Apparently washing produce doesn't necessarily remove salmonella. According to Lauran Neergaard, AP Medical Writer, if a tomato is warm and the water rolling over its surface is cold, then the fruit will absorb that water through any opening in the skin including the stem scar. If there is salmonella present on the tomato skin, it can enter the fleshy part of the tomato and the bacteria multiplies. Ms. Neergaard suggests we should wash our tomatoes, but not in cold water.
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...
In fact, salmonella may be particularly hard to prevent in a variety of crops because birds, reptiles and amphibians carry it - the same reason children should wash their hands after handling a turtle, iguana or frog. The tomato industry's guidelines already advise surrounding fields with bare soil "buffer zones" to discourage reptiles.
This is the 14th salmonella outbreak associated with tomatoes since 1990.
The FDA has launched a Tomato Safety Initiative to learn more about how salmonella gets onto and inside tomatoes. Industry practices in Virginia and Florida (the origin of several previous outbreaks) are being studied and Florida's agriculture department will begin enforcing so-called "tomato best practices" on July 1st. The FDA is also asking for the authority to set preventative controls for growers and suppliers of foods linked to repeated outbreaks of serious illness, such as tomatoes and leafy greens. Congress hasn't yet acted on that request.
Ms. Neergaard doesn't mention groundwater contamination as an issue, as discussed in this New Scientist article:
The bacteria probably come from groundwater contaminated with animal faeces, he says. Once Salmonella gets on and into a tomato, the fruit acts like an incubator. Bacteria divide even in the cool temperatures of packing houses. "If you get a few samples into the internal tissue, then they will grow for sure."
At the moment there don't seem to be any clear cut answers as to how to prevent this from happening. But for now, wash your tomatoes in warm water.