Going Bananas:

The Effect of Temperature on the Ripening of Bananas

Tracey MerzGrade 10

http://www.freeclipartpictures.com/pictures/banana.jpg

Question

Does temperature have an effect on the rate of ripening of bananas?

Background InformationA 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 5Day

Deg

rees

Bri

x

Percent Sugar

Average Results By Temperature: 22 degrees Celsius

1618202224262830

1 2 3 4 5Days

Deg

rees

Bri

x

Percent Sugar

Average Results By Temperature: 30 degrees Celsius

1618202224262830

1 2 3 4 5Day

Deg

rees

Bri

x

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, ContinuedA 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