Wednesday, May 26, 2010

Does a Banana Have More Calories Than a Kit Kat Bar?

It’s a common belief that an average banana contains the same amount of calories as a regular Kit Kat bar. In order to prove that bananas are more nutritious than Kit Kats, we carried out various chemical experiments with Benedicts solution, IKI solution and used a homemade calorimeter to analyze the carbohydrate content of each food item in question. Not only did we analyze the chemical composition of both the Kit Kat and the banana but we also conducted an experiment and analysis of both the banana and Kit Kat’s affect on the blood pressure on our test subjects to analyze how the nutritional content of each food initially affected the body.

Materials used in this experiment:
· Bananas (3)
· Kit Kat Chocolate Bars (3)
· Bunsen Burner
· Retort Stand
· Ring Clamps
· Empty Pop Cans
· Barbeque Lighter
· Ceramic Plate
· Steel Screens
· Safety Goggles
· Home Blood Pressure Kit
· Benedicts solution
· Iodine Potassium Iodide (IKI) solution
· Beaker (250 ml±5%)
· Beaker Tongs
· 2 Test tubes
· Water
· Hot Plate
· Scoopula
· Mortar and Pestle
· 4 volunteers
· Paper towels
· Heat glove
· Medicine dropper
· Stopper
· Test tube rack
· Stir stick
· Knife
· Oven (112ÂșC)
· Paper Clip

Benedict's and Iodine Testing for Carbohydrates and Starch.

Benedicts Test:
Fill a beaker with about 200 mL of water and heat it to a light boil (around 95-100 degrees C)
While this is heating, obtain a test tube and place some Benedict’s solution and a section of smashed banana in the test tube
When the water comes to a light boil, place the banana/Benedict’s solution test tube in the hot water bath for a couple of minutes and note any colour change
Repeat this with a piece of Kit Kat (ground with mortar and pestle)

This is the Benedicts solution and the banana (on the left) and the Benedict’s solution and Kit Kat bar (on the right) in the 200mL beaker of water, on the hot plate. During this process, the Benedict’s solution reacted with each food respectively, allowing us to determine the relative amount of carbohydrates.



This is the Benedicts solution and the banana (on the left) and the Benedict’s solution and Kit Kat bar (on the right) after they were removed from the 200 mL beaker water, and cooled, the banana showed a change in color, and the frothy bubbles in the Kit Kat bar/Benedict’s solution compressed.



Iodine Potassium Iodine Test:

IKI Test
Obtain a small piece of Kit Kat grind in with a scoopula, or a mortar and pestle until it has a crumbly or powdery texture.
Use a medicine dropper to drop a few drops of IKI solution on the Kit Kat and watch for a colour change and note the shade of the solution after a minute or so
Repeat this process with a few slices of banana.
This is the Kit Kat bar broken into smaller pieces and tested with the Iodine Potassium Iodide solution.



This is the Banana broken into smaller pieces and tested with the Iodine Potassium Iodide solution.



Observation Tables - Qualitative Results:


Calorimeter Procedure - How to test each substance for calories:

Procedure - Calorimeter:
Set up a retort stand with a ring clamp and iron ring.
Find an empty pop can and poke two holes through it (straight across).
Fill the can will 100mL of water and take the water’s initial temperature
Insert a glass stirring rod into the two holes and use it to support the pop can over the Bunsen burner.
Stab a small sample of Kit Kat with a large paperclip and manipulate the paperclip so that it stands unassisted.
Cut out the middle portion of a pop can and cut out a 1 cm wide slit in one spot so that a lighter can be easily inserted.



Wrap the tin that is obtained around the paperclip with Kit Kat on it. This will reduce the heat loss as it will direct the heat at the bottom of the pop can.
Ignite the small piece of food with a lighter and wait for it to fully burn. Be sure that the bortom of the pop can is centred above the flame
Measure the final temperature of the water.
Find the amout of energy in the sample by using the formula Q=mc where m is mass of water, c is specific heat capacity of water (a constant) and is change in water’s temperature.

Repeat the process with a slice of banana of about the same mass.



**It may be helpful to place the banana piece in an oven for an hour to help dry it out, so that it may combust more easily.

Tuesday, May 25, 2010

Calories in a Kit Kat Bar versus a Banana: Do Bananas Contain The Same Amount Of Calories (Kcal) As A Regular Kit Kat Bar?






However, according to the label of the Kit Kat bars, there are 220 calories in a 45g Kit Kat bar. This suggests that the results of the experiment were affected by experimental error. For instance, when the piece of the Kit Kat bar was tested, much heat escaped while it was being burned since the burning Kit Kat bar was not surrounded by an empty pop can, which would have directed the heat that it was producing toward heating the water (when the banana slice was tested, it was surrounded by a pop can, reducing the amount of escaped heat). This is the most notable factor that could have contributed to a low difference between the initial and the final temperature of the water, and ultimately, a much smaller number of calories than expected.

Does a banana or a Kit Kat bar affect blood pressure?

Observations:



Difference of initial (average) and final blood pressures in Mean Arterial Pressure (MAP):

MAP = 2/3 (DP) + 1/3 (SP) *Systolic Pressure (SP) and Diastolic Pressure (DP)



Subject 1, who ate the Kit Kat bar, shows a steady increase in mean arterial pressure after eating the Kit Kat bar. However, it cannot be concluded that eating a Kit Kat bar increases the blood pressure of a subject because subject 2 has inconclusive results with no steady pattern. Subjects 3 and 4 both had their highest mean arterial pressure after 20 minutes of eating a banana, and both had a large decline in MAP after 30 minutes of consuming the banana. Nonetheless, this does not show that a banana has an effect on blood pressure either. It seems that the banana and the Kit Kat do not affect the blood pressure of a person. The results would be more decisive if more test subjects were used to measure the effects of these foods on blood pressure.