Colorado State University Extension
SafeFood Rapid Response Network


SAFEFOOD NEWS - Summer 2002 - Vol 6, No. 4

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Enclosers

Questions and Answers Regarding E. coli O157:H7

E. coli O157:H7, which kills an estimated 60 Americans each year and sickens an estimated 73,000 more, is 10 times more prevalent in the summer than previously thought. With the recent beef recall in mind, here are some answers to questions you might have regarding E. coli O157:H7.

What is E coli? There are some types of E. coli bacteria that live peacefully in the intestines of warm-blooded animals including some food animals and humans. They keep growth of harmful organisms in check and even produce some B vitamins.

E. coli O157:H7 is a fairly new virulent strain that can cause serious and potentially fatal diseases. Scientists first identified it in the early 1980's when illness with bloody stools was reported in people who'd eaten undercooked hamburgers from fast food outlets.

How does E. coli O157:H7 get into your food? A typical scenario might be: A cow that is carrying the E. coli O157:H7 bacteria in its intestinal tract is chosen for slaughter. These animals can appear perfectly healthy and infection cannot be detected just by looking at them. If E. coli O157:H7 escapes the intestines of infected cattle during processing, it can contaminate the meat. The contaminated meat is mixed with other meat and ground for hamburger. If the contaminated meat is undercooked, the bacteria can cause severe food poisoning.

What are the symptoms and who is at most risk? Symptoms, which usually appear in 3-4 days, include severe abdominal cramps and diarrhea, which is often bloody. Vomiting and a low-grade fever may occur in some individuals and dehydration can be a complicating factor. The illness usually resolves itself within 2 weeks, during which hospitalization may be required. In the very young, the elderly and the infirm, however, long-term complications of infection with E. coli O157:H7 may include kidney failure, strokes, seizures and possibly death.

What can I do to make sure I don't ingest E. coli O157:H7? Food handling and preparation practices are the last line of defense for preventing infection from E. coli O157:H7 and other food borne pathogens. To prevent food contamination with these pathogens:

• Cook ground meat and patties to 155° to 160° F. The good news is that E. coli O157:H7 is easily destroyed at these temperatures. A thermometer that can be inserted into the food is essential to be sure the food reaches this temperature.
• Wash hands, utensils and work areas with hot, soapy water after contact with raw meat and meat patties. Sanitize for extra safety by using one teaspoon chlorine bleach per gallon of water.
• Thoroughly wash raw fruits and vegetables before eating them to remove bacteria.
• Store fresh meat below produce in the refrigerator to prevent meat juices from contaminating produce. Never place cooked meat on an unwashed plate that held raw meat.
• Don't drink raw milk and avoid unpasteurized juices or ciders.

Meat Jerky

Jerky is made by drying thin strips of lean meat to about one-fourth its original weight. In the past, preparation and heating recommen-dations for jerky have been quite general. Recommendations have included drying in the sun, oven or dehydrator. Sun drying is no longer recommended because of lack of a steady controlled heat source (140°-145°F) and the potential for contamination from animals, insects, dust and bacteria. Although drying in the oven or dehydrator allows for a safer product, illnesses in recent years due to Salmonella and Escherichia coli O157:H7 in homemade jerky products have raised questions about the safety of all methods of drying jerky products at home.

Escherichia coli O157:H7 is especially dangerous because of the severe consequences of infection, particularly for people who are young, elderly or immune compromised. The pathogen has a very low infectious dose, thus raising concerns for food products consumed raw or with inadequate cooking. In addition, E. coli O157:H7 can adapt to acidic conditions and has been found to survive many weeks on dry surfaces, even at refrigerated temperatures. Thus, there is a strong indication for the potential risk of E. coli O157:H7 surviving in dried foods.

One method for ensuring the adequate destruction of E. coli O157:H7 during jerky preparation is to pre-cook the meat to 160°F before drying. This method is currently recommended by the Meat and Poultry Hotline (1-800-535-4555) of the U.S. Department of Agriculture. Pre-cooking creates a product that is different than traditional jerky and therefore may not be well received by consumers. Also, the product may not dry evenly throughout because of case-hardening on the outside surface.

The jerky preparation methods given in this fact sheet were developed as part of a joint project between the Departments of Food Science and Human Nutrition and Animal Sciences at Colorado State University, and were found effective in reducing numbers of E. coli O157:H7 on inoculated samples by at least 5 logs.

Jerky Preparation

Use only lean meats in excellent condition. Round, flank and chuck steak, rump roast, brisket and cross rib are good choices. Highly marbled and fatty cuts do not work as well. When preparing jerky products, keep raw meats and their juices away from other foods. Remove any thick connective tissue and gristle from fresh meat. Trim off visible fat with a sharp knife. Fat becomes rancid quickly and causes the develop- ment of off-flavors during drying or storage. Freeze meat in moisture-proof paper or plastic wrap until firm but not solid.

Slice the meat on a clean cutting board while still slightly frozen into long thin strips, approximately ?- to ¼-inch thick, 1 to 1½-inches wide and 4 to 10 inches long. Slice with the grain if a chewy jerky is preferred; slice across the grain for a more tender, brittle jerky. Lay the strips out in a single layer on a clean and sanitized smooth surface (cutting board, counter top, cookie sheet). Flatten the strips with a rolling pin so they are fairly uniform in thickness.

Note: Always wash and sanitize cutting boards, utensils, and counters with hot, soapy water before and after any contact with raw meat or juices. To make a sanitizing solution, use 1 teaspoon of household chlorine bleach per quart of water.

Test for Dryness

Properly dried jerky is chewy and leathery. It will be as brittle as a green stick, but won't snap like a dry stick. To test for dryness, remove a strip of jerky from the oven or dehydrator. Let cool slightly, then bend the jerky; it should crack, but not break when bent.

When jerky is sufficiently dry, remove the strips from the drying racks to a clean surface. Pat off any beads of oil with absorbent paper toweling and let cool.

Hot Pickle Cure Preparation Method

Ingredients per two pounds of lean meat slices:

Pickling Spices:

• 1½ tablespoons salt
• 1 tablespoon sugar
• 1 teaspoon black pepper

Hot Pickle Brine:

• ¾ cup salt
• ½ cup sugar
• 2 tablespoons black pepper
• 1 gallon water

Directions:

Place lean meat slices (see Jerky Preparation) on clean cookie sheets or flat pans. Evenly distribute half of the pickling spices on the top surfaces of the meat slices. Press spices into slices with a rubber mallet or meat tenderizer. Turn slices and repeat on opposite sides. Cover and refrigerate for 24 hours.

Combine ingredients for hot pickle brine (salt, sugar, pepper, water) in a large kettle or electric fryer. Stir to dissolve salt and sugar and bring to a slow boil (175°F). Place a few meat slices at a time in a steamer basket and lower into brine. Simmer for 1½ to 2 minutes, stirring occasionally to make sure all pieces are immersed.

Pre-heat dehydrator or oven to 145°F. Lift basket out of kettle and drain off liquid. Using clean tongs, remove meat pieces and place flat, without touching each other, on clean dehydrator trays, oven racks or other drying trays. Place in pre-heated dehydrator, leaving enough open space on racks for air to circulate around the strips. Repeat process until all meat pieces have been pickled in the brine solution and placed in the dehydrator. Let strips dry at 145°F for 10 to 12 hours, or until the slices are adequately dry.

Vinegar-Marinade Preparation Method

Ingredients per two pounds of lean meat slices:

Pre-treatment dip:

• 2 cups vinegar

Marinade ingredients:

• ¼ cup soy sauce
• 1 tablespoon Worcestershire sauce
• ¼ teaspoon black pepper
• ¼ teaspoon garlic powder
• ½ teaspoon onion powder
• 1 teaspoon hickory smoked salt

Directions:

Place 2 cups vinegar in 9x11-inch cake pan or plastic storage container. Add meat strips to container, making sure vinegar covers all strips; Let soak 10 minutes, stirring occasionally to ensure distribution of vinegar on strips. Combine all marinade ingredients and place in a 1-gallon re-sealable plastic bag. Add lean meat slices to bag; seal bag and massage pieces to thoroughly distribute marinade over all meat strips. Refrigerate bag 1-24 hours.

Remove meat slices from bag, and place flat, without touching each other, on clean dehydrator trays, oven racks or other drying trays. Place trays in pre-heated dehydrator and dry at 145°F for 10 to 12 hours, or until slices are adequately dry.

Jerky Storage

Place cooled jerky strips in an airtight plastic food bag or jar with a tight-fitting lid. Pack jerky with the least possible amount of air trapped in the container. Too much air causes off-flavors and rancidity to develop. Label and date packages. Store containers of jerky in a cool, dry, dark place or the refrigerator or freezer. Properly dried jerky will keep at room temperature for approximately 2 weeks in a sealed container. It will keep for 3 to 6 months in the refrigerator and up to one year in the freezer.

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Updated Monday, August 29, 2011