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The Onion Experiment

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by

Colleen Yuen

on 18 June 2013

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Transcript of The Onion Experiment

You cannot control the amount of tears that are produced during the cutting of the onion. This shows us that we cannot control the results from the experiment. The only thing that we could control was the method we were using to cut half an onion. We could also control how long Nicole was going to cut the onion for. We also could not control the size of the onion and how big the halves are compared to each other.
The tears produced when crying comes from small glands next to the eye called the lachrymal glands. The glands produce tears when it is irritated. Onions have a chemical called syn-propanethial or otherwise known as the S-oxide. When an onion is cut open, the onion cells are releasing the enzymes (the chemical) which then diffuse through the air and it irritates the lachrymal glands which causes them to produce tears. When the gas makes contact with the eye, it stimulates a stinging and painful sensation. In conclusion, when you chew gum it forces and helps you to breathe through your mouth and this makes smaller amounts of chemicals reach the lachrymal glands, which prevents it to get irritated and release tears.
We had seven different input methods. We repeated each input method three times with the same amount of onion (half an onion) and wrote down three sets of results. We timed each method for one minute which makes each test fair. The input methods are listed in the order that we did them in
Input Methods
The Tear Scale
Discussing Variables
Input and output variable
Hypothesis
By: Candy, Colleen, Nicole, Margherita,Vanessa
The Onion Experiment
To get our output variable, we had a scale from one to five to determine the amount of tears that were produced in Nicole’s eyes. Here are the criteria for the scale that we made
If you breathe through your mouth you are less likely to cry because the chemicals from the onion won’t be breathed in through your nose and passed to your eyes which will make you cry. Chewing gum will help you breathe from your mouth, so we feel that the chewing gum method will be the most successful method.
Imput and Outcome Variables discussed? Are other Variables Controlled?
Independent/input variable: The time we used to cut up the onion

Control variables: The person we used to cut up the onion, the amount of pressure applied when cuting up the onion, and the types of onions

Outcome Variable: The outcome/dependent variable for this experiment is how much tears the person cried when cutting up the onion.
Materials
*Tub of room temperature water
*3 pieces of chewing gum (airwaves lemon and honey)
*3 candles
*A lighter
*Goggles
*Sharp knife (scalpel-type)
*Normal knife
*Freezer
*11 normal sized white onions
*Chopping board
*A stopwatch
Reason for hypothesis
The input variable is the independent Variable: The different methods used to cut the onions.
The output variable is the dependent variable: The numbers of tears produced.
chilling the onion in the freezer 15 minutes before cutting
wearing tights goggles
The candle method (leave the candle next to it for 1 minute before chopping)
Chopping underwater
Using a sharp knife
Chewing gum
Nothing/Normal method
Why do you cry when you chop onions?
When you chop an onion, you break the cells releases its contents. When the cells are broken, the enzymes react with amino acid sulphoxides in the cell that was originally separated from the enzyme. The reaction produces sulfenic acid, which is unstable and forms a volatile gas called propanethiol S-oxide. They go into our eyes and eventually react with water in our eyes. The acidic solution irritates our eyes releasing more tears.
Our experiment allowed us to investigate which methods can stop us from crying when chopping an onion, in other words, prevent the propanethio S-oxide from getting into our eyes and reacting with the tears in our eyes and which are the most efficient.
After the experiment, we found out that out of
-Chop the onion under water
-Chewing gum
-Chopping with a lit candle next to the chopping board
-Chilling the onion in a freezer beforehand for 15 minutes
-Wearing tight goggles
-Using a sharp knife
-No method
Freezer, tight goggles, sharp knife and chewing gums methods are the most efficient out of every single method.
No tears
A sparkle in the eye but no tears
Small droplets of tears, and disappearing at cheek leve
Lots of tears but no runny nose or other symptoms
Bawling your eyes out
The Results
Following the criteria above, our results from the experiment turned out as follows
This is because freezing the onion lowers the temperature of the onion which slows down the cells actions in the onions. This causes longer time for the enzyme to react to form propanethio S-oxide. This also allows us to finish chopping the onion as quick as possible to prevent too much of the irritating substances from reaching our eyes.
Using tight goggles is efficient because it actually prevents the Propanethio S-oxide from getting into our eyes.
Chewing gums help because when we are cutting onions, it forces you to breathe through your mouth, and the air you breathe out disperses the amount of Propanethio S-oxide to reach to your eyes. But this does not always work, and cannot be explained with a definite answer.
As for sharp knife the sharp edge slices through the onion cells, this breaks less cells and release less of the irritating chemicals as the surface area that slices through the onion is smaller.
Results
In conclusion, out of all the methods we used, there is not a single method that can stop us from crying when cutting onions. But simple methods like chilling the onion, wearing goggles, or contact lenses, using a sharp knife can help. And with going back to our hypothesis, we found that, it is true that chewing gums is efficient and do stop you from crying.
Tear Scale
Chilling the onion in the freezer 15 minutes before cutting - 1, 2, 2
Wearing tights goggles - 2, 1, 2
The candle method (leave the candle next to it for 1 minute before chopping) 3, 2, 2
Chop the onion underwater - 2, 2, 2
Using a sharp knife - 1, 2, 2
Chewing gum - 2, 2, 1
Nothing - 3, 4, 3
All our results were calculated by using this tear scale. The lower the number the better the method is.
Procedures
Underwater method
1: Get half a peeled onion
2: Fill a tub full with room temperature water
3: Place an onion under water and get a knife
4: Cut the onion underwater for 1 minute and remember to use a timer to keep track of time and make it a fair test
5: When the one minute is up, use the tear scale to see how many tears you produce
Chewing gum method
1: Get half a peeled onion
2: Chew a piece of gum for 30 seconds prior
3: Cut the onion while still chewing the gum for 1 minute, use a timer to keep track of time and make it a fair test
4: When the one minute is up use the tear scale to see how many tears you produced
Conclusion
Candle method
1: Get half a peeled onion
2: Light a candle and place it next to the chopping board and onion for one minute prior and use a timer to keep track of time and make it a fair test
3: When the one minute is up, start cutting the onion with the flame still lit
4: When the one minute is up use the tear scale to see how many tears you produced
Use a sharp knife
1: Get half a peeled onion
2: Cut the onion with the sharp knife for 1 minute, use a timer to keep track of time and make it a fair test
3: When the 1 minute is up, use the tear scale and see how many tears you have produced
Explanation of the Bar Chart
Chilling the onion
1: Get half an unpeeled onion
2: Place it in a freezer with cling wrap for 15 minutes prior, use a timer to keep track of time and make it fair test
3: When the 15 minutes is up, place the onion on the chopping board and take off the peel
4: Cut the onion for 1 minute, use a timer to keep track of time and make it a fair test
5: When the one minute is up, use the tear scale to see how many tears you have produced
Looking at the bar chart, the underwater method the most reliable as all the results stayed the same for each of the three trials, and the range was just three on the tear scale.
The most unreliable methods were the candle method and doing nothing method (Normal) as the results were the highest on the tear scale.
The methods that worked and had a low tear scale result were: the freezer method, wearing tight goggles, using a sharp knife, and chewing gum.
In Conclusion
Most Reliable:
The Underwater Method
Most Unreliable:
The Candle Method and the Nothing Method
Methods That Worked:
The Freezer Method, Wearing Tight Goggles, Using a Sharp Knife, and Chewing Gum.
Wear tight goggles method
1: Get half a peeled onion

2: Put on a pair of lab goggles and stuff tissues in the gaps in between

3: Cut the onion for 1 minute using a timer to keep track of time and make it a fair test

4: When the one minute is up, use the tear scale to see how many tears you have produced
The tighter and smaller the error bars are the better the results. If the range is small, the results are more reliable.
Nothing method
1: Get half a peeled onion

2: Get a normal knife and cut the onion for 1 minute, use a timer to keep track of time and make it a fair test

3: When the 1 minute is up, use the tear scale and see how many tears you have produced
Data Table and Bar Chart of Results
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