Sanitation and Safety: Part 6

Killing by cooking

Ordinary cooking of foods destroys many disease-causing organisms. Others can survive low-temperature cooking (low crock or oven temperatures or low-temperature frying). It is important to realize that it is not the temperature of the oven or the fry pan but the internal temperature of the food that must reach lethal levels.

Lethal temperatures vary widely depending on the kind of food, the kind of bacteria, and the length of time the food remains at a given temperature. It takes 3 to 10 minutes to destroy salmonella bacteria in whole egg at 138°F (59°C) but less than a minute at 150°F (66°C). Most bacteria and other disease-producing organisms cannot survive a temperature of 165°F (74°C). This includes the parasite trichina (trick-eye'-na), sometimes found in fresh pork, which causes trichinosis in humans.

On the other hand, though a temperature of 165°F (74°C) will kill staph bacteria, it will not destroy toxin they may have already produced in foods at danger-zone temperatures, and it is the toxin that makes the diner ill. Some special forms of bacterial life called spores can also outlive high temperatures and grow into active disease-causing organisms later. (Clostridium perfringens is one example.) So it is a mistake to think of cooking as a cure-all for food-borne disease.

Cleaning and sanitizing

High temperatures or chemical solutions can kill bacteria surviving on equipment and utensils. The temperature of the rinse water in the automatic dishwasher must be kept at 180°F (82°C) for 10 seconds to kill bacteria and sanitize the dishes. Where such hot temperatures cannot be maintained, as in washing utensils by hand and in cleaning counters, floors, and large equipment, a chlorine or iodine solution is used in the final rinse to kill bacteria. State and local laws specify what chemical may be used in what quantity, and it is your responsibility to follow these guidelines carefully.

Here is a general procedure used for washing equipment and tools by hand in a three-compartment sink. Temperatures given are those required by federal standards? To follow them you will need long rubber gloves and long-handled brushes.

1) On the drainboard, scrape and prerinse with a spray in order to keep the wash water as clean as possible.

2) In the first sink, wash with detergent in 140-150°F (60-66°C) water, removing all food particles and traces of grease. If necessary for utensils with baked-on foods, soak in detergent and scrape and prerinse again.

3) In the second sink, rinse in clean warm water at 150-160°F (66-71°C). Change the water frequently, or use a sink with an overflow drain and keep the water running.

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