Copyright 1992 by O. Peter Snyder, Jr., Ph.D.
Hospitality Institute of Technology and Management
(May 1998 edition)

In America today, government inspection of raw food does not control microbiological contamination. This means that we have contamination by bacteria, viruses, fungal toxins, and parasites in all types of food, to include meat, poultry, fish, vegetables, dried foods, and fruits. Depending on the food source and the ethics of the grower, harvester, producer, and supplier, food can be either very safe or very hazardous. Without doing detailed microbiological testing, there is no way to know the safety of the food, unless the supplier will certify that it is safe. Therefore, we must assume that all food has sufficient contamination so that if one were to touch raw food and then touch ready-to-eat food, enough pathogens to make people ill would be transferred.

People who prepare food are another major hazard. When people feel well and have no symptoms of illness, they can be excreting millions of pathogens per gram in their feces and urine. Therefore, we must assume that everyone working with food has high levels of pathogens in their feces and urine and that the toilet paper was only partially effective. This means that high levels of pathogens must be removed from the fingertips and under the fingernails before food is prepared.

Kitchen cleaning compounds and insect control chemicals are hazardous and must be separated from food. A much more serious hazard is that some people are allergic to certain foods. Every food served at a group feeding must have a small placard listing ingredients so that people can avoid foods containing ingredients that they cannot tolerate. Finally, hard foreign objects such as rocks, metal, and fish bones must be controlled as much as possible.

Storing food in the refrigerator is used to control the growth of pathogens in food. However, it is now known that a number of pathogens can grow and multiply in food at temperatures below 45F. If people consume sufficiently large numbers of these pathogens or their toxins in food, they can become ill and even die. Bacterial pathogens known to grow below 45F include:

Yersinia enterocolitica
Listeria monocytogenes
Aeromonas hydrophila 
E. coli
Clostridium botulinum, Type E 
Vibrio parahaemolyticus 
Bacillus cereus 
Salmonella spp. 
Staphylococcus aureus 

Hot holding and cooling are also major critical safety points. Once food is cooked, it still contains heat-resistant spores of pathogenic microorganisms. Cooked food must be kept above 130F for safety or cooled less than 2 inches thick to control the spores.

While there are many variables associated with how long cooked food is safe, a conservative standard is that no leftover food should be kept in a 40F refrigerator for longer than 5 days.
1. There must be one person in charge of food safety at each event. That person should have an accurate electronic, digital thermometer, not a bimetallic dial thermometer, a very inaccurate device. That person assures that cold food coming from home is less than 55F and stored at 40F. Hot food must be over 140F. All cold food is served at less than 50F, and hot food is served above 150F and is pasteurized.

2. Buy food from suppliers who consistently provide you will the freshest food. Do your best to have suppliers certify their products as safe. They should have a HACCP program.

3. Thoroughly double wash fresh vegetables and fruits in cold water (no salt or added chemicals) to remove excess agricultural chemicals, and the fecal microorganisms that may have gotten on the food from workers who harvested the food. Do not try to wash pathogens from meat, poultry, and fish. This is ineffective and will only spread pathogens around the kitchen. Simply cook / pasteurize the meat, poultry, and fish to make it safe.

4. It is best to prepare food cold at home and heat it at the gathering. If food is cooked at home, it must arrive at the gathering at a temperature above 130F and kept at or above 140F.

5 Prevent cross-contamination of pathogens from raw meat, poultry, and fish to food that will not receive further cooking. Clean "as you go" the area, cutting boards, knives, etc., with soap, a scrub brush, and hot water before you begin. Washing is the critical control.
     If there are no sinks for washing equipment, set up a 3-pan line. First, scrape clean your utensils. Then, rinse in the first dish pan with a scrub brush and at least 4 gallons of water. Wash with detergent in the second dish path with at least 4 gallons of detergent water and a scrub brush. Finally, rinse in at least 4 gallons of water in the third pan. Air dry.
     If you want to sanitize, do so with a solution of 1/4 teaspoon of bleach in a 1-quart squirt bottle. Do not use a sanitizer bucket, because the dirt in the solution inactivates the chemical. Squirt sanitizer on the surface of, for example, a cutting board. Spread it with a clean paper towel and let the cutting board air dry. Everyone must clean up when finishing a task to prevent cross-contamination.

5. When entering the kitchen or food preparation area, everyone must wash his or her hands, using a fingernail brush and the double hand washing method to remove any feces that might be on fingertips or under fingernails. The key, critical controls are the nail brush, which loosens possible fecal pathogens on fingertips, and the water, which washes the pathogens down the drain. Use the following double hand wash procedure.

6. After you are in the kitchen, your hands can become contaminated with pathogens. Pathogens in food are in much lower concentration than fecal pathogens. Therefore, only a single wash (about 5 seconds) with soap and lather, but without the nail brush, will make them safe. Paper towel dry.

7. Wearing plastic gloves is acceptable but not recommended. Studies have shown that people abuse the use of gloves, and the glove surfaces become more contaminated than ungloved hands. Also, fingernails punch through the ends of gloves. Bacteria grow to very high numbers on sweaty, gloved hands. If sanitized utensils are used as much as possible to handle food, and hands are clean before food is touched, ungloved hands will be safer than gloved hands. People are more careful about keeping hands clean than keeping gloves clean.

1. Be sure that any refrigerator or cold chest has an accurate thermometer, and that it reads less than 40F. Note that mechanical refrigeration standards in the U.S. are tested with the door never opened and with nothing in the refrigerator. This is a very unrealistic operating standard. A refrigerator is designed only to keep cold food cold, not for cooling hot food. When you are cooking ahead many hot foods, items such as chicken, beef cubes, pasta, cubed potatoes, etc. can be pre-cooled after cooking in cold, running tap water and then, with some ice, if necessary.

2. Calibrate ovens with an oven thermometer. Leave plenty of time to cook food. Many ovens are underpowered and take a longer time when they are full of food vs. one pan.

3. Always design recipes to cook and serve food hot, not to cool and reheat. If you must cool and reheat food, use ice for cooling so that you will not overload the refrigerator.

4. Keep detergent, buckets, paper towels, and clean cloth towels handy to clean food contact surfaces as food is prepared.

5. Get enough cube ice (prepared from potable water) to make sure that any necessary cooling can be accomplished correctly. Get enough sealable bags so that leftover food, no more than one inch thick, can be placed inside, the bags sealed, and the food cooled by immersing the bag of food in slush ice. Get 1/2 pound of ice for each pound of food to be cooled.

6. Use an electronic digital thermometer to measure food temperatures. It is critical to get food to pasteurization temperatures to make it safe. The minimum temperature/time standards are:

 8.7 minutes 
2.7 minutes 
 52 seconds
15 seconds
5.2 seconds 

7. Do not use a microwave oven to pasteurize food to make it safe. Microwave ovens do not produce uniform enough temperatures throughout the food to guarantee safely cooked food, unless great care is taken. Use the microwave oven only for reheating safe food or for preheating the food to about 100F and then transferring it to an oven to finish pasteurization.

1. Begin by pre-preparing all vegetables and fruits. These items take a long time to clean and cut up and are relatively safe until cooked. a. Do not let the food temperature rise above 50F during pre-preparation of raw food products.
b. If necessary, ice down the food at the end of pre-prep to keep food temperatures below 45F until preparation.
c. Vegetables covered with water will not turn brown. Putting a little lemon juice in the water, 2 tablespoons per quart, will further assure the safety of the vegetables when they are held cold prior to being used.
2. Pre-prep meat, poultry, and fish. a. These items can be highly contaminated with pathogens. If these foods are marinated in 2 tablespoons vinegar or lemon juice per pint of water in a refrigerator, it will help control the growth of pathogens on the surface.
b. Cutting items in pieces of less than 1 inch in size will help ensure faster, more uniform cooking and cooling. During pre-prep, do not let the temperature rise above 50ºF to avoid spoilage.
3. Pre-prep sauces and gravies. a. When making sauces, make sure that they get to a temperature of above 150F for safety. It will take temperatures of 175F or higher for them to thicken. Therefore, when sauces do thicken, you know that the infective pathogens are destroyed.
b. If sauces are to be kept hot, keep them covered at 150F for quality. Covering is critical, because it prevents evaporative cooling of the sauce's surface.
c. If sauces must be made ahead of time, make a double strength concentrate sauce and, when finished, add the other half of water as ice (made from potable water) so that the temperature is cooled to less than 45F in perhaps 5 to 10 minutes.
Large pieces of meat, roasts
1. Roast at an oven temperatures above 250ºF. Get the center temperature above 130ºF in less than 6 hours to prevent the multiplication of pathogens during cooking.

2. Do not roast meats, etc. on a spit or stick the meat with a fork, because it will unnecessarily contaminate the center of the food. Always wash the stem of a thermometer before putting it into cooked, ready-to-eat food.

3. The minimum final food holding temperatures and times for people's satisfaction are:


Rare roast beef 
 8.7 minutes 
Medium rare roast beef 
 2.7 minutes
 Pork, lamb, veal 
52 seconds 
 15 seconds 
Poultry white meat 
5.2 seconds 
Poultry dark meat

4. Once cooked, meat should be covered to prevent cooling and held in a 140F hot holding environment. For quality and nutrition, it should be consumed within 30 minutes. To assure safety, the temperature of the meat must never go below 130F. Spore (pathogen) outgrowth starts just below 130F, at 127.5F.

5. To assure safety, take care of leftovers within 2 hours after they are removed from the heat. Cut the meat to thinner than 1 inch thick, wrap in plastic or put in a sealable bag. Since the refrigerator is not built to cool more than a few pounds of food, immerse the plastic bag in ice for rapid cooling.

Thin foods (e.g., hamburgers, chicken, fish, egg dishes, casseroles)
1. Assume that the product is highly contaminated. For instance, assume (unless that supplier certifies that the eggs are pasteurized), that fresh eggs in whole, uncracked shells come from Salmonella-infected chickens and that the yolk is contaminated.

2. Cook at a moderate temperature so that the food gets uniformly pasteurized.

1. Hot sauces will be safe as long as they are cooked to thicken and kept above 130F. Leftover sauces are difficult to cool. It is suggested that they be thrown out.

2. Cold or lukewarm sauces such as mayonnaise, hollandaise, or Béarnaise, rely totally on the amount of added vinegar and lemon juice for safety. Use commercial product with controlled acidity.
Fruits and vegetables
1. If fruits and vegetables are cut and served cold, the only safety control is washing. Before being cut, they must be washed twice in a lot of clean, cold water. If there is a lot of water and good agitation, each washing will reduce the bacteria about 10 to 1, for a total of a 100-to-1 reduction.

2. If you have serious doubts about the vegetables, such as celery or radishes, they can be blanched in 160F water for 15 seconds, then plunged into slush ice water. This will reduce the vegetative pathogens on the surface to virtually zero.

3. Once vegetables such as potatoes, green beans, and onions are cooked, they must be served promptly, and not left at room temperature. The deadly spores of Clostridium botulinum can outgrow and multiply in 24 hours in warm vegetables to produce the most deadly toxin known.

1. Make acidic fruit desserts such as apple pie as much as possible. Because of the acid in them, they will not grow pathogens. They will spoil because of mold.

2. Avoid desserts with eggs and milk unless they are cooked to above 160F, cooled continuously to 45F in less than 15 hours (less than 2 inches thick), and kept at 40F.

Cold combination salads
1. Make all salads with ingredients that are pre-cooled to 40F. DO NOT MAKE SALADS WITH WARM INGREDIENTS. For example, put canned fish or meats such as tuna or ham in the refrigerator 24 hours before use, along with the salad dressing. For salad potatoes, peel, cut into 1/2-inch cubes, cook, pour off the hot water, wash in cold tap water, and finish with ice until they are 45F. The same procedure should be used for hard boiled eggs, pasta, etc. Mix all cold ingredients quickly so that after mixing, the salad is below 50F.

2. To increase the safety of the food, use several acid additives (vinegar, lemon juice, pickles, mustard, etc.) at the maximum quantities that are acceptable to people's taste. If salads are made with all cold ingredients and a sufficient amount of commercial dressing and other acids, they will be virtually "goof proof".

3. Always put acid food such as salads into stainless steel, glass, or plastic containers. Acid can dissolve other materials such as pottery and glaze, and can make people ill from the heavy metals in the glaze.

Hot combination dishes
1. These can be made at home if made with ingredients that are cold and raw, or have been cooled rapidly in slush ice after cooking.

2. It is best to bring all pre-prepared, cold, raw ingredients to the location (e.g., church), mix and heat them there, and serve.

3. Once hot, the food must be kept at 130F or hotter. For people to judge hot food as properly hot, they must be:


Hot beverages

Above 175F, food can burn people's mouths. Do not serve food that is too hot.

  Home-canned meat and vegetables are potentially very hazardous. If you choose to serve home-canned food that is not very acid, such as green beans, meat, or potatoes, the food MUST be brought to a BOIL (212F) for 10 minutes in a covered pan. This will inactivate any Clostridium botulinum toxin that might have formed in the food after home canning. Hundreds of people each year are poisoned by improperly home-canned food. A few die. Be careful.

1. Be very cautious of hot holding transport boxes. They probably will not keep food hot for more than one hour. Test transport boxes before you need them, to be sure that you know how to use them safely. Always preheat boxes by filling with boiling water. Load the boxes as full as possible with vey hot food. Then, tape the lid closed and do not open until you are ready to serve. Each time the lid is removed and steam escapes, about 5F of temperature is lost

2. A good way to transport and hold cold food is to wrap it in plastic or put in a sealable plastic bag, and immerse it in ice in an insulated transport box. Take out only what you need. Keep the rest of the food covered with ice.

3. During service, keep hot food above 140F, and cold food below 40F.

4. If you are serving at an event where you cannot keep food hot or cold on the serving line, make sure that all food is served and eaten within 2 hours. Put out food on the line progressively so that the pathogens in the food do not have enough time to multiply to a hazardous level. Do not let people take hot food away for later consumption. If leftover food sits at room temperature for about 8 to 12 hours, vomiting and diarrhea are almost guaranteed from pathogens that will grow.
1. Try not to have any hot leftovers. If you insist that food be saved, then package less than 1 inch thick and cool in slush ice (made from potable water) to 45F. If you do not cool food correctly, the people who eat the leftovers could have severe diarrhea or vomiting from the spores that survive cooking and outgrow and multiply during slow cooling.

2. If you have cold leftovers and they were kept at less than 40F, make sure that they stay at this temperature and are eaten in less than 5 days for quality.
1. Appoint a QA person in charge of safety. Have a training session for all food preparers so that everyone knows your policies, procedures, and standards.

2. Always use a calibrated, electronic, digital thermometer to check food temperatures when cooking, never a bimetallic dial thermometer.

3. All food handlers are assumed to be ill and must wash their fingertips and under their fingernails using the double wash method to remove the fecal pathogens.

4. All raw food must be assumed to be contaminated with high levels of pathogenic microorganisms.

8.7 minutes
2.7 minutes 
52 seconds 
15 seconds 
5.2 seconds
About the author: Dr. Snyder is the president of the Hospitality Institute of Technology and Management, an education and consulting firm specializing in foodborne illness prevention and total quality assurance management. A former Army food R&D officer and associate professor in food science at the University of Minnesota, Dr. Snyder is nationally known as a leader in HACCP-based food safety self-control education and implementation.
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