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LAB07: PINEAPPLEENZYMES&JELL-O
BACKGROUND
If you have ever made Jell-O by cooking the powder that
comes in a box, there is a warning on the instructions that tell you not
to add fresh or frozen pineapple to the gelatin. Why? You will design
an experiment to test what happens when you add pineapple to
gelatin. You know enough organic chemistry now to figure this out...
WHAT IS JELL-O ANYWAY?
That sweet colorful treat is made out of hides, bones, and
inedible connecting tissue from animals butchered for meat. All these
tough parts are made of proteins. In fact, the extracted gelatin is a
protein. So, why do you think gelatin gets thick and jelly like when
you cook it?
Gelatin can be extracted from any kind of animal, but cows
are most common. You've probably seen how it gets stiff and Jell-O
like after it sits in the fridge. That's because boiling the chicken in
water extracts the gelatin from the carcass (bones & cartilage), just
like a miniature version of the commercial gelatin factories!
Commercial gelatin making starts by grinding up bones. The
crushed bones are then soaked in a strong base (high pH) to soften
them, and then passed through stronger acid (low pH) solutions, until
the end result isn't recognizable as bones at all! Then the whole mess is
boiled for hours to extract the gelatin (this part really stinks) Finally, the
gelatin layer is skimmed off the boiling pot, and dried into a powder.
With added sugar, flavor, and artificial color, it's a jiggly dessert!
It was popularized in the Victorian era with spectacular and
complex "jelly moulds". Gelatin was sold in sheets and had to be
purified, which was very time-consuming. It also made gelatin desserts
the province of the relatively wealthy. In 1845, industrialist Peter
Cooper obtained a patent (US Patent 4084) for powdered gelatin.
Forty years later the formula was sold to a LeRoy, New York-based
carpenter and cough syrup manufacturer, Pearle B. Wait. He and his
wife May added flavoring to the powder and named it “Jell-O” in
1897.
The rest is history... Made from bone… made from protein… so
it must be tough stuff! So why can’t you put fresh pineapple in it?
LET'S LEARN A LITTLE ABOUT PINEAPPLES!
The pineapple plant (Ananas comosus) is a plant that belongs
to the bromeliad family. It is thought to have originated in Brazil. In the
1950s, pineapple became the United State’s second most important
fruit and Hawaii led the world in both quantity and quality of
pineapples. However, times have changed and now, all canned
pineapple comes from overseas, largely from the Philippines.
As with some other tropical fruits, the pineapple fruit contains
an enzyme that breaks down, or digests, protein. This protease
enzyme in pineapple is called bromelain and the protease enzyme
found in papaya(another tropical fruit) is called papain. These
enzymes are extracted and sold as meat tenderizers.
METHOD (PROCEDURE) & MATERIALS:
In this lab, you will be given an array of materials and you will
be asked to design your own experiment to test the effect of
pineapple on gelatin. Remember: The canning process involves
cooking or heating fruits or vegetables to a high temperature (to kill
off any bad bacteria that might be present) before sealing the food in
a can. The goal is to understand what is actually going on in the
pineapple-gelatin mix at a chemical level as well as understanding
what affects the function of enzymes.
Materials
 Fresh pineapple
Canned pineapple
 Jell-o
 Assorted containers
Boiling & ice water
Spoons, stirring thingies
2. Design a controlled experiment that shows the effect of raw
pineapple on gelatin. Make sure your experiment description includes
the following:
1. Hypothesis. Remember hypotheses are written as “
statements.
2. A detailed experimental design which will include:
A. The effect of fresh pineapple on gelatin.
B. The effect of canned pineapple on gelatin.
C. How gelatin behaves without any fruit additives.
D. A data table
3. Write up your brilliant and detailed experimental plan (see below).
4. Perform your experiment once you receive approval of your
experimental design from your teacher.
SAFETY
Wear your goggles. If you take them off anywhere but near the door,
you will receive a percentage off your grade every time you do it.
Don't fool around with any of the materials or equipment. I may have
enough liability insurance, but you can't run fast enough.
This lab is worth a total of 33 points and
20% of your overall grade in class.
EXPERIMENTAL PLAN
Teacher Approval ______
1. Title_______________________________________________________ [1 pt.]
2. Team Members ________________________|_______________________|
__________________________|___________________________
3. Research Question: What is affecting what?
[1 pt.]
____________________________________________________________________
____________________________________________________________________
4. Hypothesis (Research Prediction): What results do you expect?
_______________________________________________________
[1 pt.]
____________________________________________________________________
5. Experimental Design (number & describe your procedures)
______________________________________________________________ [1 pt.]
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
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6. Independent Variable______________________________________ [1 pt.]
7. Dependent Variable_______________________________________ [1 pt.]
8. What other factors must be controlled?
[1 pt.]
____________________________________________________________________
9. Data Table (Create a table to collect your data in.)
Title of Data Table & Graph
[1 pt.]
____________________________________________________________________
10. Proposed Plan to Analyze Data
[1 pt.]
(How will you compare these numbers after you collect them?)
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
11. What results you would need to see in your data to support your
hypothesis: ___________________________________________________[1 pt.]
____________________________________________________________________
____________________________________________________________________
12. Complete the experiment.
13. Collect the data in your Data Table.
14. Graph your results if appropriate.
15. Answer the Summary Questions.
(Lab adapted from explorebiology.com)
DATA TABLE
[5 pts.]
(Draw your table below. You must use a straight edge. to make it
neat.)
DATA GRAPH
[5 pts]
(Glue in/draw an appropriate-sized square of graph paper here.)
SUMMARY QUESTIONS
1. Clearly describe the results of your experiment. In which test tubes
did the gelatin jell, which did not.
[1 pt.]
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
2. Clearly explain the results of your experiment. Why did some
containers of gelatin jell, why did others not. Be specific!
[1 pt.]
____________________________________________________________________
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____________________________________________________________________
____________________________________________________________________
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3. What is the enzyme in your experiment ______________________[1
pt..]
4. What is the substrate in your experiment?____________________ [1 pt.]
5. What is (are) the product(s) in your experiment
_________________________________
[1 pt.]
6. What type of organic molecule is gelatin?___________________ [1 pt.]
7. What type of organic molecule is the enzyme, bromelain?
_________________________________
[1 pt.]
8. Write a “word equation” to describe the chemical reaction that
occurs when pineapple is mixed with the gelatin.
[1 pt.]
____________________________________________________________________
9. Is the reaction of bromelain and gelatin synthesis (building) or
digestion (breakdown)?
[1 pt.]
____________________________________________________________________
10. Why were the results of the freshly cooked pineapple different
than the results of the fresh, raw pineapple? Be specific! What
happened to the enzyme?
[1 pt.]
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
11. What is meat tenderizer and what does it do? Be specific!
[1 pt.]
____________________________________________________________________
____________________________________________________________________
12. Explain what is meant by denaturing a protein.
[1 pt.]
____________________________________________________________________
____________________________________________________________________
13. Design an experiment you could do in science class to test at
exactly what temperature the pineapple enzyme denatures (unfolds).
Be specific!
[1 pt.]
____________________________________________________________________
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