The Effect of Natural Ethylene on the Ripening of Bananas
Author(s):
Dean Papadakis and John Olson
Research Question:
Can the Ripening Process of
Bananas be Speeded Up by
Placing the Fruit in the Presence
of Already Ripened Fruit?
Growth & Development Experiment
SED 695B; Fall 2007
Standards addressed:
Investigation and
Experimentation
Here are some un-ripened and ripened bananas.
The probe (below) is placed in contact with the
banana at an angle to measure the reflectivity of
light using the Vernier Light Illumination Probe.
1. Scientific progress is made by
asking meaningful questions and
conducting careful investigations. As
a basis for understanding this
concept and addressing the content
in the other four strands, students
should develop their own questions
and perform investigations. Students
will:
a.
b.
c.
d.
f.
g.
j.
k.
Select and use appropriate
tools and technology (such
as computer-linked probes,
spreadsheets, and graphing
calculators) to perform tests,
collect data, analyze
relationships, and display
data.
Identify and communicate
sources of unavoidable
experimental error.
Identify possible reasons for
inconsistent results, such as
sources of error or
uncontrolled conditions.
Formulate explanations by
using logic and evidence.
Distinguish between
hypothesis and theory as
scientific terms.
Recognize the usefulness
and limitations of models and
theories as scientific
representations of reality.
Recognize the issues of
statistical variability and the
need for controlled tests.
Recognize the cumulative
Here below is the Light Sensor (photometer) with
the LabPro Interface
Independent
variable
Time
(Over the Course of
Several Days)






Dependent variables
Controls
Series
Amount of Color Change
from Green to Yellow
(measured with a
photometer)
A single green banana placed in a
sealed plastic bag to see how fast
it ripens without additional help.
Series1 Banana Alone in a Baggie
Series 2 Banana with Ripened
Bananas
Series 3 Banana with Ripened
Apples
Materials
Green Bananas,
Yellow Ripened Bananas,
Apples,
Computer with Vernier LabPro Interface
and
Vernier Photometer and
Plastic Bags
Procedures
1. Green, un-ripened bananas and yellow ripened bananas are purchased
from the store.
2. The Vernier Light Meter (photometer) is used to see if the difference
in
color between green and yellow can be measured.
3. Three series of experiments are set up with series one having a sealed
plastic baggie with one un-ripened banana inside.
4. Series two has a sealed plastic bag with one un-ripened banana in the
presence of three other yellow ripened bananas.
5. Series three has a sealed plastic bag with one un-ripened banana in
the
presence of three week-old apples.
6. The three un-ripened bananas are measured every two days to
measure
the progress of the ripening process and to see if there is any
difference in
the amount of yellow or dark spots between the three sets of bananas.
The measurement involves measuring the intensity of the reflected
light
from the banana skin, in units of LUX.
Data Value
1
2
3
4
5
6
7
8
9
Photometer Data
Time (seconds)
0.0
0.02
0.04
Etc.
Illumination (LUX)
The data collected in this
table would be collected
using a photometer.
Here is some illumination
data collected for a green
un-ripened banana, showing
the reflected light from the
green skin has a value that
is in the high 300’s.
Here is the graph of the data
shown above, which shows
the statistics of the data in
the top left corner,
indicating an average lux
value of 376 and a standard
deviation of 17 lux.
Here is some illumination
data collected for a yellow
ripened banana, showing
the reflected light from the
yellow skin has a value that
is in the low 500’s.
Here is the graph of the data
shown above, which shows
the statistics of the data in
the top left corner,
indicating an average lux
value of 506 and a standard
deviation of 23 lux.
Observations:
The two sets of data above, show that using a photometer is a
viable way of measuring differences in the color of the skin,
through the amount of reflected light from the skin.
Principles Involved:
It is known that ethylene (C2H2) gas is produced during the
ripening process of bananas and fruits. This ethylene gas acts as a
hormone to speed up the process of ripening. When bananas are
shipped from one country to another, the goal is that the ripening
process will be slow. When the bananas reach the supermarkets
where they will be purchased, the goal is that the rate of the
ripening process will be increased. An ethylene generator can be
used for this process.
One context where the ripening process should be slow is when
NASA wants to send fruit on a mission, and the fruit must be
stored for a week or so at a time before a mission. The ripening
process should be slowed down as much as possible so that the
fruit will be ready for space.
References & Links:
http://media.nasaexplores.com/lessons/02-042/5-8_1.pdf
The website above provides a procedure that middle school students can use to test the ripening of bananas.
http://postharvest.ucdavis.edu/datastorefiles/234-726.pdf
This powerpoint presentation in the website above shows several images of the ripening process under various conditions.