Wednesday, April 16, 2014

MCFARLAND: Best conditions for contamination

By REBECCA MCFARLAND, Reaching Out | 8/21/2013

If you read my column two weeks ago, you might recall that I wrote about the Cyclospora outbreak and wrote briefly about how food gets contaminated. Biological hazards are by far the greatest threat to food safety. As a review, biological hazards (or microorganisms) are viruses, bacteria, parasites and fungi. Illness-causing microorganisms cause most foodborne illness outbreaks, and are known as pathogens.

Many viruses, bacteria and parasites cause illness but cannot be seen, smelled or tasted. On the other hand, some fungi, like mold, change the appearance, smell or taste of food, but they might not cause illness.  

If you read my column two weeks ago, you might recall that I wrote about the Cyclospora outbreak and wrote briefly about how food gets contaminated. Biological hazards are by far the greatest threat to food safety. As a review, biological hazards (or microorganisms) are viruses, bacteria, parasites and fungi. Illness-causing microorganisms cause most foodborne illness outbreaks, and are known as pathogens.

Many viruses, bacteria and parasites cause illness but cannot be seen, smelled or tasted. On the other hand, some fungi, like mold, change the appearance, smell or taste of food, but they might not cause illness.  

Pathogens need six conditions to grow. You can remember them by the acronym F.A.T. T.O.M.

• Food — Pathogens need an energy source to grow, such as carbohydrates or proteins. These are commonly found in food such as meat, poultry, dairy products and eggs.

• Acidity — Remember back to high school chemistry when you were checking the pH of different substances? As you might recall, pH is a measurement of how acidic or alkaline a food is. Food with a pH between 0.0 and 6.9 is acidic, while food with a pH between 7.1 and 14.0 are alkaline. Pathogens typically do not grow in alkaline food, such as crackers, or highly acidic food, such as lemons. They grow best in food that contains little or no acid (a pH of 4.6 to 7.5).

• Temperature — Pathogens grow well in food held between the temperatures of 40 degrees and 140 degrees. This range is known as the temperature danger zone.

• Time — Pathogens need time to grow. When food is in the temperature danger zone, pathogens grow. Under ideal conditions, certain bacterial populations can double in as short as nine minutes.

• Oxygen — Some pathogens require oxygen (aerobic) to grow, while others grow when oxygen is absent (anaerobic).

• Moisture — Pathogens require moisture in food to grow. Perishable foods requiring refrigeration usually have very high moisture contents. Moist food left over for long periods of time provides adequate moisture for bacterial growth.

Any type of food can be contaminated. But some types are better able to support the growth of pathogens. These types of foods have the right F.A.T. T.O.M. conditions that pathogens need to grow. They have the natural potential for contamination because of the way they are grown, produced or processed. They are also commonly involved in foodborne illness outbreaks.

Foods most likely to become unsafe include:

• Milk and milk products;

• Meat, beef, pork and lamb;

• Fish, shellfish and crustaceans;

• Baked potatoes;

• Tofu or other soy products;

• Sliced melons and cut tomatoes;

• Eggs and poultry;

• Heat-treated plant food, such as cooked rice, beans and vegetables;

• Sprouts and sprout seeds; and

• Untreated garlic-and-oil mixtures.

Be sure to read my next column, coming Sept. 5, to learn what you can do to keep your food safe.

Rebecca McFarland is the family and consumer sciences extension agent for Frontier Extension District No. 11, which serves Franklin County. For more information, call her at (785) 229-3520 or email rmcfarla@ksu.edu

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