If you've been following the news for the past two months, you are probably aware that the U.S. is in the midst of an outbreak of an especially dangerous form of E. coli: a bacterium that can cause severe food poisoning and lead to kidney failure.
The second massive E. coli outbreak was traced to romaine lettuce this year. Almost 100 people in 22 states have been sickened between March and April 29, with a higher than usual number requiring hospitalization.
Unfortunately, it's not a rare event. Close to six dozen E. coli outbreaks have been traced to leafy greens since 1995 with nine serious outbreaks in the United States and Canada related to romaine lettuce between 2002 and 2012.
The Centers For Disease Control And Prevention have identified one field in Yuma, Arizona, as the source of about 10 percent of the infected romaine lettuce although most victims have no discernible link to that particular farm. Tracing links in the lettuce supply chain is difficult because most greens do not bear labels identifying where they were grown.
With the source of the majority of the illnesses still unknown, the CDC believes that the current epidemic will be self-limiting because chopped greens have a short shelf life and the mass shipment of greens is making its annual seasonal shift from Arizona to California.
Salad season is here. Do you have to give up eating raw greens to safeguard your health?
Not necessarily. Paying closer attention to how you buy and prepare those salad staples can help you guard against the next big outbreak of E. coli associated with raw leafy greens.
Buying locally helps. Greens grown in your own garden or by small regional farmers (especially organic farmers) are less likely to be contaminated.
And the less the greens are handled, the safer they may be: pre-chopped romaine and bagged and packaged salad mixes appear to be at the center of the current problem. You can also put vinegar, that all-purpose household cleaner, to a new "clean and green" use.
In an April 16 article in Food Safety News (foodsafetynews.com), microbiologist Carl Custer suggests that dousing the greens with vinegar before eating them is a simple way for home cooks to make their salads safer, citing multiple studies that have shown vinegar to be effective in removing E. coli and salmonella from leafy greens. The greater the soaking time, temperature and concentration of acetic acid -- the primary component of household vinegar -- the greater the effect.
To clean your greens, look for vinegar that is about 6 percent acetic acid by volume. You can find the concentration in small print on the back label of the bottle.
Rice vinegar and wine vinegars are not acidic enough to kill viruses and bacteria. Balsamic, which usually checks out at about 6 percent acidity can do the job as can apple cider and white vinegar with 5 percent acidity.
The first step to cleaner greens is to any remove any bruised or broken leaves, which can let the pathogens into the plant's cells where they can resist any attempts to clean them out. The second step is to douse the greens with the vinegar and let them sit while you finish peeling, slicing and chopping the other salad ingredients.
When you are ready to assemble your salad, give the greens a quick rinse in clean water, shake, spin or towel them dry, season to taste with salt and pepper, and toss it all with your favorite dressing. Note that you may not need to add additional vinegar to a basic vinaigrette, and that a creamy dressing might be the best balance for any vinegar remaining on the leaves.
You can find the Spanish version of this story here.