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In
BrainFood, we learn that warm air is less dense
than cold air. The design of a refrigerator is
a great example of this in the real world. Experiment
with food, freshness, and refrigerators to prove
that warm air is less dense than cold air.
The
Centers for Disease Control and Prevention (CDC)
in Atlanta, GA estimates that there are up to 33
million cases of food poisoning in the United States
each year.
Bacteria are
major causes of food poisoning. Symptoms of bacterial
food poisoning occur because food-borne bacteria
release poisons as a byproduct of their growth
in the body.
| Materials |
| • |
2
slices of white bread
|
| • |
2
slices of cheese (such as cheddar)
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| • |
2
heads of lettuce
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1
sealable plastic bag
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refrigerator |
Step
1: Place one slice of bread and one
slice of cheese on the lowest refrigerator shelf.
Step
2: Place one head of lettuce in the
crisper bin located at the bottom of the refrigerator.
Step
3: Place the other slice of bread, the
other slice of cheese, and the other head of
lettuce on a countertop at room temperature.
| • |
Compare
the refrigerated food to the room-temperature
food over a 14-day period. Which ones stay
fresher longer?
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| • |
Use
this experiment as a basis for a discussion
on the process of bacterial growth. |
Some
examples of the most common types of bacterial
food poisoning are Salmonella; Escherichia
coli (sometimes talked about often in
the news, and also referred to as E. coli);
and Botulism, which is the deadliest
of the bacterial food-borne illnesses . The risk
of salmonella can be decreased by washing your
hands well before you handle or prepare food.
E.
coli mostly is found in raw or undercooked
ground beef, although raw milk has also been
a source of food poisoning by E. coli. Reduce
the risk of E. coli by cooking
meat thoroughly.
Take
home message! Always handle and store pre-packaged
foods according to the directions on the label.
Also refrigerate food promptly when storing food
that is left over.
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