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Middle School Food Safety Lessons
Lesson
3 High Pressure Treatment
National
Health Education Standards
(grades 5-8)
1:1; 4:3; 6:3
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| introduction |
- Connect this lesson with
Lesson 2 Chain of Food by asking students to think about how
the chain of food even in the 1800’s and early 1900’s
was shorter than today. Remind the students that even their grandparents
living today could tell them how they kept food safe without
refrigerators,
sophisticated manufacturing, or electricity.
- Ask the students:
“Can you suggest ways that food was
preserved in the days before electricity?”
- List the student’s suggestions:
Salting, drying, canning, chilling, freezing (by use of ice boxes
and ice houses)
- Inquire of students:
“What do all these methods have in common?” (They kill or slow down
bacteria growth; change in texture of the food.)
- State:
“In addition to destroying bacteria,
scientists are continually searching for new methods to kill bacteria
without damaging the
appearance, taste, texture, or nutritional value of food. We will
hear more about this in our video.”
6. State:
“I would like the students who brought
in food to discuss that food and tell us what they know about
how it is preserved.”
7. Ask the students:
“What do you think are the positives
and negatives of the various methods of preservations?”
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| activity 1 |
- State:
“I am handing out some questions for
you to think about while you are watching Dr. X and the Quest for
Food Safety, Module 3.”
- “What new ways of processing foods did Dr. Sizer talk about
in the video?” (The discussion should lead to pasteurization, irradiation,
and ultra high pressure treatment.)
- “What are the benefits of ultra high pressure treatments over
other forms of pasteurization?” (High pressure
can kill bacteria without affecting the nutrition, color, or
texture of food.)
- “Why can you use ultra high pressure treatment with orange juice
and not a marshmallow?” (Orange juice contains
water that protects it from being crushed by the ultra high
pressure. A marshmallow
contains
air and would be compressed to the size of a BB.)
- Show the video Dr. X and the Quest for Food Safety, Module3,
Processing and Transportation (7 minutes).
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| activity 2 |
Ask the students:
- “What new ways of processing foods did Dr. Sizer talk about
in the video?” (The discussion should lead to pasteurization,
irradiation, and ultra high pressure treatment.)
- “What
are the benefits of ultra high pressure treatments over other
forms of pasteurization?” (High pressure can kill bacteria
without affecting the nutrition, color, or texture of food.)
- “Why can you use ultra high pressure treatment with orange
juice and not a marshmallow?” (Orange juice contains water
that protects it from being crushed by the ultra high pressure.
A marshmallow contains air and would be compressed to the size
of a BB.)
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| activity 3 |
- State:
“Let’s see how ultra high pressure
treatment works to preserve food.”
Ask two students to fill the two plastic bottles completely to the
top with water, put a grape in each bottle, and tightly close
the caps. The water bottle represents the ultra high pressure equipment
and the grape is the food being pressurized.
- Ask the students:
“Who thinks they can crush the grape by squeezing the bottle?” Have
the students try to crush the grape. “Why can’t
you crush the grape?” (Water in foods protects the food
structure from physical damage during compression. As long
as the food is
mostly air-free and contains water, pressure doesn’t “crush” the
food.)
- Ask the students:
“Why is pressure being applied to the food?” (Pressure
is applied to kill the bacteria.)
- Ask the students:
“How are bacteria killed by the high pressure?” (Bacteria
are living organisms and the pressure affects their cellular
functions. When high pressure is applied to all sides, the
enzymes are inactivated.)
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| closure |
Review the lesson by saying:
“Throughout the ages, people have found
ways to preserve food. Scientists are continually developing new,
improved methods of preserving
foods.
In addition to pasteurization and irradiation, bacteria are now also
killed by a new process called ultra high pressure treatment.” |
| integration ideas |
Ask the students to:
- Research and write about food preservation methods in a different
period of history. Essays should be posted to share with classmates.
- Hypothesize about other ways they can think of that science
might help us preserve foods in the future, and how they would
design an experiment to test the hypothesis? Indicate which foods
they would use the “process” for.
- Interview a neighbor
or grandparent who lived as early as 1925. Ask them to write
an essay to share with the
class (by
posting their essays) about how their family preserved food when
they were young. Compare these methods with today’s lesson.
- Investigate
how people in a country in the Far East preserve food and to
write an essay to explain their findings. Post the
essays.
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