Bacteria:
Bacteria are microscopic organisms that can be
found virtually everywhere. Many of the foods coming into a food
service establishment or into our homes are already contaminated with
not only spoilage bacteria but also pathogenic bacteria. As such some
of the major goals of a food safety program are to: slow bacterial
growth; destroy the bacteria already present on a food item; to
prevent bacteria from being transferred from one food to another; and
to keep the bacteria present on a food handler from being transferred
onto the food.
Unlike viruses, bacteria are capable of
reproducing in foods. Rapid growth of bacteria occurs when potentially
hazardous foods have been time and temperature abused. Potentially
hazardous foods include, but are not limited to: meats,
poultry, eggs, dairy products, seafood, cooked grains, cooked
vegetables, cooked legumes, cut melons, sprouts, and garlic in oil
preparations.
Time and temperature abuse involves allowing
potentially hazardous foods to remain in the temperature danger zone,
140oF - 41oF, for more than 4 hours.
Controlling pathogenic bacteria in foods
includes the following:
Cooking *** -Foods
must be cooked to the required temperatures and times necessary to
destroy pathogens. These temperatures vary depending on the foods
involved. Chapter 3 of the FDA Food Code lists cooking times and
temperatures for various foods http://vm.cfsan.fda.gov
Holding *** -Hot
foods should be held at or above 140oF and cold foods
should be held at or below 41oF. If this cannot be
accomplished then foods held at ambient temperatures after 4 hours
should be discarded.
Cooling *** -Cool
foods rapidly to 41oF either by a one-stage or two-stage
method. The one-stage method involves cooling from 140oF to
41oF within 4 hours. The two stage methods involves cooling
foods from 140oF to 70oF within 2 hours and
cooling further from 70oF to 41oF in an
additional 4 hours. Rapid cooling of food can be accomplished by
placing the food in a blast chiller or a walk-in refrigerator after
the food has been portioned into shallow pans or cut into smaller
portions. Using an ice bath is another option for smaller batches of
food. Rapid cooling of food can be accomplished by placing the food in
a blast chiller or a walk-in refrigerator after the food has been
portioned into shallow pans or cut into smaller portions. Using an ice
bath is another option for smaller batches of food. Keeping a cooling
temperature/time log can be helpful in determining if the method used
is cooling foods to the proper temperature in the allotted time.
Reheating ***
-Foods should be reheated rapidly, within 2 hours, to 165oF
or above. Reheat foods only once. Do not use hot holding equipment or
slow cookers, such as a crock-pot, to heat foods.
Cross-contamination
- Cross-contamination of food occurs when bacteria is transferred from
one food item to another. This can be prevented by using separate
utensils and equipment for different types of foods. Another option is
to wash, rinse, and sanitize equipment and utensils between use on
different types of food. Some examples of where cross-contamination
can occur are: between raw poultry and other raw meats; between raw
vegetables and cold cuts; between raw meats and ready-to-eat foods
such as salads, etc.
Hand washing and personal hygiene
- Humans carry bacteria all over their bodies. It is important to know
that "healthy" food handlers can transmit pathogenic
bacteria to other individuals through their contact with food. Food
handlers must wash their hands frequently. It is especially important
that hands are washed after using the toilet, coughing, sneezing,
smoking, eating, drinking, handling raw meats, garbage, cleaning, or
any other time hands may have been contaminated. Smoking, eating, or
drinking should occur in designated areas only and hands must be
thoroughly washed after these activities. Always minimize hand contact
*** Use metal-stemmed probe thermometers to check
food temperatures.
DO NOT USE GLASS THERMOMETERS!
Viruses:
Viruses are microscopic organisms that are found
in living organisms. The viruses involved in
foodborne illnesses generally come from humans
either via food handlers or from foods contaminated at the source.
Viruses do not reproduce in foods but rather
need a living host to reproduce. Therefore time and temperature abuse,
and potentially hazardous foods are of no importance when it comes to
controlling viruses. In addition, cooling, hot holding, and cold
holding are not important factors in controlling viruses. But don’t
forget that these are very important considerations in preventing the
growth of bacteria.
The following factors are important in
controlling viruses in foods:
Source-Obtaining
foods from a reputable source is very important. Specifically,
shellfish obtained from waters contaminated by human sewage have been
associated with a number of viral outbreaks. Viral gastroenteritis
outbreaks have also been associated with fresh produce that has been
contaminated with human waste.
Handwashing and personal hygiene
-Because fecal-oral transmission is a major route for getting viruses
from the foodhandler and into food that is consumed, handwashing is
especially important. Hands must be washed thoroughly after using the
toilet. This includes not only handwashing after a bowel movement but
also after urinating. Again, hand contact with food should be
minimized when preparing foods that will not be thoroughly cooked.
Cooking - For
foods like shellfish that may have come from contaminated waters,
thorough cooking is important. The CDC’s Control of Communicable
Diseases Manual recommends cooking shellfish from contaminated waters
to 185oF-194oF for 4 minutes or steaming for 90
seconds before eating. Because shellfish are filter feeders,
contaminants may be concentrated in their bodies during this feeding
process and a high cooking temperature is necessary to kill these
contaminants. Shellfish should always be obtained from
non-contaminated waters. Avoiding raw or undercooked shellfish is
especially important for children, the elderly, and immunocompromised
individuals.
Reheating - If
cooked foods have been contaminated after the cooking process,
reheating to the proper temperature of 165 F or above can destroy this
contamination.
Washing - Cleaning
fresh produce may help reduce the level of contaminants.
Note: References to times, and temperatures were
taken from the 1999 FDA Food Code. If you have specific questions,
please contact your local health department or the Department of
Public Health. Further references are found on the "LINKS"
page.
References:
FDA Food Code 1999
Control of Communicable Diseases, Sixteen Edition, Abram S. Benenson, Editor
Web Sites of Interest:
www.cfsan.fda.gov
http://vm.cfsan.fda.gov/