The Effect of Heat on
Enzyme Activity
By: Kelly Duffy, Grade 9.
Problem
 How hot does it need to be for pineapple enzymes to
stop working?
Research
 Enzyme
 A catalyst can be used over and over again in a
chemical reaction: it does not get used up. Enzymes
are very much the same except that they are easily
denatured by heat.
 Denature
 All enzymes are made of protein; that is why they are
sensitive to heat, pH and heavy metal ions.
Hypothesis
 If the pineapple enzymes are heated to 37° Celsius,
then they will stop working and won’t be able to melt
the jello.
Materials
 A scale
 One fresh pineapple
 Two boxes of jello mix
 A candy thermometer
 A tray
 A pot
 24 dishes
Procedure

Room was 23 degrees Celsius.

Experiment was not interfered with.

Two packets of jello mix were poured into a 22 by 33 cm glass pan.

236 milliliters of boiling water were poured into glass pan.

Solution was stirred for two minutes.

236 milliliters of cold water were poured into glass pan.

Solution was stirred for a minute.

Glass pan was placed in refrigerator at five degrees Celsius for four hours to jellify.

The jello was cut into 3cm slabs.

Pineapple was cut into 1cm cubes; core was excluded.

Twenty-four cubes in total.
Procedure

Initial temperature of water taken; 23.5 degrees C.

Dishes labeled at 5-degree increments after 23.5°C.

Pineapples placed in pot of water and put on low heat.

Pineapples taken out at 5-degree increments.

Pineapple cubes cooled for thirty-five minutes.

Pineapple cubes placed on jello slabs.

The first 13 pineapple cubes melt jello completely.

The next four only melt part of the jello.

The pineapple cubes stopped melting the jello after being heated to 103.5 degrees C.
Variables
 Independent variable: The temperature of the
pineapple cubes.
 Dependent variable: Whether or not the enzymes are
working.
 Control: The pineapple that hadn’t been heated.
 Constants: Pineapple, jello.
Data
Rate of Enzyme Degration
20
y = 1.51x - 170.99
Percent Change in mass (%)
0
-20
-40
-60
-80
-100
-120
0
20
40
60
80
o
Temperature ( C)
100
120
140
Conclusion
 Hypothesis: If the pineapple enzymes are heated to 37°
Celsius, then they will stop working and won’t be able
to melt the jello.
 The hypothesis was not supported.
 The enzymes stopped melting the jello after being
heated to 103.5° Celsius.
 The experiment could be improved by testing the effect
of heat on the enzymes of many fruits.
Thanks To…
 Those in attendance listening
 Works Consulted
 http://www.education.com/science-fair/article/effectof-heat-on-enzyme-activity/
 http://www.wordiq.com/definition/Enzyme
 http://www.purchon.com/biology/enzymes.htm
 Any Questions?