Going Bananas:
The Effect of Temperature on the Ripening of Bananas
Tracey Merz
Grade 10
http://www.freeclipartpictures.com/pictures/banana.jpg
Question
Does temperature have an effect on the rate of ripening of bananas?
Background Information
A refractometer is a device that measures the speed of light in a substance.
Ripening in fruit is controlled by the plant hormone ethylene. Ethylene increases the levels of certain enzymes in fruit, including amylase, pectinase, and chlorophyll.
At low temperatures, enzymes have low kinetic energy.
As temperature increases, the enzymes gain energy.
http://www.yourgemologist.com/Refractometer/refractometer1.jpeg
Refractometer
Hypothesis
If bananas are stored at 10, 20, or 30 degrees Celsius, then those stored at 30 degrees Celsius will ripen the most quickly, while bananas stored 20 degrees Celsius will ripen at a slower rate and those stored at 10 degrees Celsius will ripen the slowest.
Materials
Fifteen bananasMetal dinner fork and knifeThree dinner platesCheeseclothScissorsThree opaque containersDextroseWaterA refractometerA refrigeratorAn incubator
ProcedureThe control was made by placing a few drops of the
0% dextrose-water solution on the lens of the refractometer to find the degrees Brix, and then doing the same with the 10%, 20%, 30%, and 40% solutions.
5 bananas were placed at 10 degrees, 5 bananas at 22 degrees, and 5 bananas at 30 degrees Celsius.
A banana kept at 10 degrees Celsius was cut, mashed, and placed on cheesecloth. A few drops of juice was then squeezed onto the lens of a refractometer.
One banana was used at each temperature for five consecutive days.
VariablesIndependent: The temperature at which the
bananas were storedDependent: The rate at which the fruit ripenedControl: Dextrose-water solutions of 0%,
10%, 20%, 30%, and 40% sugarConstants: The amount of time in the
experiment, the type of bananas, where and when the bananas were purchased, the refractometer, the amount and type of cheesecloth, the scissors, the fork and knife used, the plates, the type of containers in which the bananas are stored, the type of sugar in the control
Average Results By Temperature: 10 degrees Celsius
1618202224262830
1 2 3 4 5
Day
Deg
rees B
rix
Percent Sugar
Average Results By Temperature: 22 degrees Celsius
1618202224262830
1 2 3 4 5
Days
Degre
es B
rix
Percent Sugar
Average Results By Temperature: 30 degrees Celsius
16
18
20
22
24
26
28
30
1 2 3 4 5
Day
Deg
rees B
rix
Percent Sugar
Day P-value
1 0.002535687
2 2.740910E-05
3 3.016280E-06
4 6.400000E-05
5 2.940120E-05
The P-value for each day was well below 0.05.
Results From ANOVA Testing
ConclusionThe hypothesis was supported. Bananas stored
at 30 degrees exhibited ripening after one day, those at 22 degrees ripened after four days, and those at 10 degrees showed no significant ripening.
The p-values were well below 0.05, showing the data found is repeatable and statistically significant.
The bananas ripened at an average of 0.978 degrees Brix per day. This formula could be used to find the Brix on other days or temperatures.
Conclusion, Continued
A possible source of error was that experimentation was performed at various times of the day, so the time period that the bananas ripened each day was different.
Further experimentation could include using a prolonged period of time and other temperatures.
In a practical application, consumers and vendors wishing to expedite the ripening process of bananas can stow them in a warm location.
Works CitedAntony, W., Staley, D., Matta, M., & Waterman, E. (2008). Amino acids and their
polymers. In Chemistry (pp. 769-773). Boston, Massachusetts: Pearson Prentice Hall.
Batt, C. (1999, September 29). Glucose sweetens fruit as it ripends. Retrieved October 15, 2010, from Cornell Center for Materials Research website: http://www.ccmr.cornell.edu/education//.html?quid=205
Biology Online. (2005, August). Growth and plant hormones. Retrieved October 19, 2010, from Biology Online website: http://www.biology-online.org//10_growth_and_plant_hormones.htm
Daintith, J., & Rennie, R. (2010). Refractometer. Retrieved October 15, 2010, from Facts On File, Inc. database.
Hopkins, W. (n.d.). Flowers and fruits. Retrieved October 6, 2010, from Facts On File, Inc. database.
Kendrick, M. (2009, August 17). The origin of fruit ripening. Retrieved from Scientific American website: http://www.scientificamerican.com/.cfm?id=origin-of-fruit-ripening
Mueller, S., & Vasquez, S. (2009). Refractometer calibration, use, and maintenance [Article]. Retrieved from University of California Cooperative Extension website: http://cefresno.ucdavis.edu//.pdf