NFS 220 Lecture Notes - Lecture 8: Frozen Food, Foodborne Illness
11 Jun 2018
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Preparing Food Safely
Thawing
Most bacteria will not grow in frozen foods, but they will begin to multiply again when food
is thawed and left in the danger zone. There are three safe ways to thaw food:
In the refrigerator: at or below 4 degrees Celsius. Large frozen items like a roast will take at
least 24 hours for every 2.5 milos. Even small amounts of frozen food require a full day to
thaw in the refrigerator.
In cold water: the frozen food must be leak proof, water proof packaging. Submerge in cold
tap water, changing the water every 30 minutes as the food thaws.
In a microwave: a microwave oven may be used to thaw small quantities of food, but
remember that microwave ovens do not thaw food evenly.
Small quantities of food can be cooked from a frozen state, but they will take longer to cook
than the recommended time for fully thawed foods. Always check that food has reached a
safe internal temperature before ending the cooking step.
Preventing Cross Contamination
1. Always clean and sanitize cutting boards, utensils, and other food contact surfaces
between uses
2. Use separate cutting boards for potentially hazardous raw foods and ready to eat foods.
Color coded boards are a good idea.
3. Keep raw foods away from cooked foods. Keep soiled dishes away from clean dishes.
Cooking to the Correct Temperature
The cooking step for many potentially hazardous foods is a critical control point. Cooking to
the correct temperature is the critical limit, or the point at which pathogens will be killed. In
order to be sure that foods have reached the critical limit temperature, always use a food
thermometer to check the internal temperature of the food.
-food may look cooked on the outside well before it has reached a high enough temperature
to kill pathogens
-always use a food thermometer to ensure that foods have reached a safe temperature
Hot Holding Foods
Hot holding equipment such as chafing dishes, steam tables, crock pots, and rice cookers are
specifically designed to keep food at a safe temperature between when it is cooked and
when it is eaten.
Cooling Foods
Improper cooling is one of the leader causes of foodborne illness. In order to reduce the
amount of time that food remains in the danger zone, hot food must be cooled from 60 to
20 degrees Celsius within two hours, and then cooked from 20 to 4 degrees Celsius within
the next four hours.
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Document Summary
Most bacteria will not grow in frozen foods, but they will begin to multiply again when food is thawed and left in the danger zone. There are three safe ways to thaw food: In the refrigerator: at or below 4 degrees celsius. Large frozen items like a roast will take at least 24 hours for every 2. 5 milos. Even small amounts of frozen food require a full day to thaw in the refrigerator. In cold water: the frozen food must be leak proof, water proof packaging. Submerge in cold tap water, changing the water every 30 minutes as the food thaws. In a microwave: a microwave oven may be used to thaw small quantities of food, but remember that microwave ovens do not thaw food evenly. Small quantities of food can be cooked from a frozen state, but they will take longer to cook than the recommended time for fully thawed foods.
