Safer Salads Summary

This article was written by the late Sally Jaeger-Altekruse, former OCMGA member, for our Winter 2007 newsletter

In the middle of October, I was walking through the Appleton Public Library and my eye caught a heading on the magazine rack. What I found was very interesting and I would like to share it with all of you. The article was entitled, “Safer Salads”, was written by Jorge M. Fonseca and Sadhana Ravishankar working at the University of Arizona and was published in the American Scientist, Volume 95 on pages 494-501.

The researchers begin by stating that the number of outbreaks, for fresh produce, of food poisoning caused by microorganisms has risen in recent years. They mention the following possible explanations:

  • People are eating more fresh fruits, vegetables and salads than ever before.
  • More meals are eaten outside the home at restaurants or public gatherings which is the most common setting for outbreaks.
  • More people are in contact with the food we eat and with large volumes of food.
  • More of today’s produce is imported from abroad where standards may be less strict.
  • Transit times from field to table can be longer.
  • Reporting of consumer illnesses are more abundant and more accurate both at the local and national levels.
  • Some scientists believe that proliferation of antimicrobials and antibiotics are partly to blame.

Several studies have shown an inverse relation between populations of natural microflora and pathogenic bacteria in soil, produce & surfaces in general.

To get an idea of the increase in outbreaks, the researchers put forward these statistics:

“For the 25 year period from 1973 until 1997, 32 states reported 190 produce-related outbreaks which together involved 16,058 illnesses, 598 hospitalizations and 8 deaths.”

“For the 14 years between 1990 and 2004, produce was implicated in 639 outbreaks involving 28,315 cases, a threefold increase in half the time.”

They next follow up with information on the individual pathogens responsible for the outbreaks. Two of the most common are Salmonella and E. coli 0157 :H7. I found these facts to be quite interesting on them:

Salmonella is an intestinal microbe that animal shed in their feces and soil that contains fresh or incompletely composted manure from animals can act as a reservoir for the bacteria. Salmonella is acid-tolerant so it survives well in low pH fruit and vegetables. “If produce that is grown in contaminated soil is not washed thoroughly, Salmonella on the surface can be spread to the inside portion during slicing or cutting.” (I guess this means we all need to do a better job at composting manure!)

E. coli was once more associated with ground beef, with recalls of raw beef and undercooked hamburgers, but now affects fresh produce also. ‘The rise in E coli-tainted fruits and vegetables probably comes from cattle operations, which can contaminate fields through feces or feces-laced irrigation water.” We need to also be concerned about cross- contamination between meat and fresh produce which can occur many places along the food chain. Although some can occur during processing, “nearly two-thirds … associated with produce have occurred during late summer and fall, when warm temperatures and outdoor cooking can subvert good hygiene, and about half … have involved cross-contamination during food preparation.”

Contamination can occur through several ways. Bacterial or parasitic pathogens can develop on the surface of fruits and vegetables or inside the flesh through damaged sites. Some studies suggest that contaminants can enter through the root system of plants and of course contamination can occur by people who work with and around the produce by not washing hands often enough and then coming in contact with the food the U.S. Environmental Protection Agency mandates a minimum waiting period of almost a year after animal husbandry operations cease before growers can cultivate the same field for edible fresh crops.” This is because “Fields that are used to contain animals are more likely than other places to harbor enteric pathogens in the soil;”

“For the same reason, raw manure is a dangerous soil additive for croplands and should be adequately composted (with sufficiently high temperatures) before use as a fertilizer for food crops.”

“Given the risk of having animal feces in contact with food crops, one might think that organically grown crops – which use organic fertilizers such as composted manure instead of synthetic fertilizers – would be especially likely to be contaminated with enteric pathogens. However, this hypothesis appears to be untrue; No clear differences exist between organically grown and conventional produce in terms of microbial safety.” The article goes on to suggest that “new regulations say that growers of certified organic produce must carry a certificate that proves that such products are pathogen-free.”

So how do they suggest we should protect ourselves? It boils down to some very common sense ideas:

  • DO wash produce vigorously with lukewarm tap water before eating;
  • DON’t save washed produce for later (unless you dry it with a salad spinner or towel);
  • DO keep produce that tolerates low temperatures in the refrigerator;
  • DON’T eat produce that looks or smells spoiled;
  • DO trim away bruises, damaged areas and the stem scar;DON’T cross-contaminate foods or surfaces, particularly when handling raw meat or eggs;
  • DO wash hands, kitchen surfaces and tools before and after preparing foodDO wash hands often during food preparation.

In closing, I found it interesting that the authors “prefer to avoid salad bar and all-you-can-eat buffets because so many individuals (many of whom, statistically, failed to wash their hands after using the toilet) have come in contact with the food.”

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