Medicine for the Outdoors
Medicine for the Outdoors

Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.

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Tips for Avoiding Food-Borne Illness

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There has been a great deal of press lately about contamination of food and in particular, fresh produce. The focus has been on Escherichia coli ("E. coli") and Salmonella typhimurium ("Salmonella") infections, but there are many other bacteria, such as Campylobacter, Shigella, and Vibrio species, that also cause debilitating gastroenteric infections.

The U.S. Food and Drug Administration (FDA) recently advised consumers about how to reduce the risk of foodborne illness from fresh produce. The advice is superb, and so I will use it as the foundation of a more comprehensive approach to produce handling and preparation that takes into account the realities of wilderness and foreign adventure travel. The italicized advice is the original offered by the FDA. The non-italicized comments that follow are mine:

Buying Tips for Fresh Produce

1. Purchase food that is not bruised or damaged. Penetrating wounds to the food that can introduce bacteria through the surface are probably worse than a bruise, unless the latter is extensive and indicates a large volume of underlying rot.
2. When selecting fresh cut produce - such as a watermelon or bagged mixed salad greens - choose only those items that are refrigerated or surrounded by ice. This is practical in an urban market, but not likely an option in an outdoor market or from street vendors. If you are trekking, you will be carrying your produce without refrigeration, so will be avoiding most items intended for raw consumption, unless they can tolerate prolonged periods of lack of refrigeration without decomposition. As you can see from the photo, you will have many opportunities to buy fruit and vegetables that has been peeled. If you look closely at the photograph, you will notice that the fruit is covered with insects, whose tiny feet spread germs.
3. Bag fresh fruits and vegetables separately from meat, poultry and seafood products when packing them to take home from the market. This is a great recommendation. Abide by it.

Storage Tips for Fresh Produce

1. Certain perishable fresh fruits and vegetables (like strawberries, lettuce, herbs, and mushrooms) can be best maintained by storing in a clean refrigerator at a temperature of 40 degrees F or below. If your're not sure whether an item should be refrigerated to maintain quality, ask your grocer. Don't carry these. They are high risk under the best of circumstances.
2. All produce that is purchased pre-cut or peeled should be refrigerated within two hours to maintain both quality and safety. Again, don't buy or carry pre-cut or peeled fruits or vegetables.
3. Keep your refrigerator set at 40 degrees F or below. Use a refrigerator thermometer to check. What if it's cold outside? Is that equivalent to refrigeration? The answer is, only if the environmental temperature is constant and within the accepted ranges for domestic refrigeration, from a safety perspective. If your food freezes or becomes too warm, it is at risk for destruction and/or contamination. Coolers with ice maintained at proper temperature are acceptable, but do not mitigate the other forces of improper hygiene, like introduction of dirt (e.g., bacteria).

Preparation Tips for Fresh Produce

1. Many precut, bagged produce items like lettuce are pre-washed. If so, it will be stated on the packaging. This pre-washed, bagged produce can be used without further washing. You shouldn't be carrying this sort of item in the backcountry.
2. As an extra measure of caution, you can wash the produce again, just before you use it. Precut or prewashed produce in open bags should be washed before using. This seems to conflict with the advice immediately above. If you have clean hands and reliably disinfected water, it seems like a better recommendation than the one above. However, remember that most of the pre-washed items are quite safe, so you need to be sure that you aren't taking a good situation and making it worse.
3. Begin with clean hands. Wash your hands for 20 seconds with warm water and soap before and after preparing fresh produce. Amen! Do this before handling any food. Hand sanitizer is an alternative to soap and water. Remember, it is important to wash hands even if handling something that will be emerging from a wrapper, like an energy bar, if there is a chance that you will touch the food before it passes your lips.
4. Cut any damaged or bruised areas on fresh fruits and vegetables before preparing and/or eating. Produce that looks rotten should be discarded. This is an excellent suggestion. Use a clean knife to do the cutting. When you cook meat and produce, you should thoroughly clean the cooking implements (e.g., knife, cutting board) if they have been used for handling meat before they are used for preparing produce.
5. All unpackaged fruits and vegetables, as well as those packaged and not marked pre-washed, should be thoroughly washed before eating. This includes produce grown conventionally or organically at home, or produce that is purchased from a grocery store or farmer's market. Wash fruits and vegetables under running water just before eating, cutting or cooking. You likely won't have running water, so use disinfected water intended for this purpose.
6. Even if you plan to peel the produce before eating, it is still important to wash it first. This is because you don't want to drag microscopic infectious organisms that you cannot see with the naked eye from the surface down into the part of the food that you intend to eat.
7. Washing fruits and vegetables with soap or detergent or using commercial produce washes is not recommended. This is because the residue of these products, when not completed removed from the food, can be toxic and make you ill.
8. Scrub firm produce, such as melons and cucumbers, with a clean produce brush. Mechanical forces greatly improve your ability to remove infectious micro-organisms.
9. Drying produce with a clean cloth or paper towel may further reduce bacteria that may be present. This is from the mechanical effect and from removing any surface moisture that may continue to carry infectious bacteria, viruses, and/or cysts.

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photo by Paul Auerbach
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About the Author

Dr. Paul S. Auerbach is the world’s leading authority on wilderness medicine.

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