Experiment OB3A, To test a variety of foods for the pressence of startch.
The Experiment involves the use of chemicals. So wear safety goggles and gloves during the experiment.
Today the chemical we will be using is Iodine solution. Which is Redish / Brown colour.
And it will stain blue / black when startch is present.
The foods we will be testing are Potatoe, Flour and Milk.
The experiment simply involves adding a few drops of Iodine. To each food sample.
When a few drops are added to the potatoe. It will stain Blue / Black in colour.
Which indicates startch is present.
When we add the chemical to flour. Again it will stain Blue / Black.
And when we finally add the solution to the milk, there is no colour change...
Indicating that there is no startch present in milk.
That concludes Experiment OB3A...
Experiment OB3B. Test a variety of foods for the pressence of reducing sugars.
As with all experiments involving he use of chemicals.
Safety glasses and gloves must be worn.
3 Food samples we are going to use today are: Milk, Glucose Solution and Water. Which is acting as our control.
The chemical involved is "Benedict's Solution." And it is added in equal volumes to each food sample.
The food samples are then heated in a water bath.
So, I'm going to add Benedict's Solution to each of the testubes...
You add an equal amount of Benedict's to the amount of liquid in the testube.
The testubes then need to be given a brief shake. To ensure that the liquids are fully mixed...
Experiment - OB3C. To test a food sample for the presence of fat.
Once again, we will need out Safety goggles and gloves.
This experiment involves: Rubbing the food sample on Brown paper.
I'm using butter, today. So, place a sample of butter onto the brown paper.
And then, Rub the food sample on the brown paper. And take off the butter afterwards...
And what we are looking for is, the presence of this spot. Which is known as a "Translucent" spot.
It's similar to a grease spot. And it allows light to pass through it, but you can't actually see through
the spot. And once you get that spot on the brown paper. That indicates the sample HAS fat in it.
If you don't get that spot. Then the food sample does not contain fat...
And that is the end of experiment OB3C...
Experiment - OB3D. To test a variety of foods for the presence of Protein.
Again, Safety goggles and gloves must be worn when handling chemicals in the lab.
Today, we will use 2 food samples. Water and Milk. The chemicals involved in this test...
Are "Sodium Hydroxide" and "Copper Sulfate."
The first stage involves adding Sodium Hydroxide to the food samples. And you must add aprox. an equal
volume of sodium hydroxide to the food sample being tested.
The testubes must be briefly shaken to ensure the chemicals are mixed.
And the last stage of this experiment involves adding a few drops of copper sulfate.
As you can see copper sulfate is a Blue chemical. And if there is protein present in the sample, It will
stain purple, when it meets the sample.
As you can see, there is no colour change in the testube containing the water. Which indicates there
is an Protein is absent in water. When added to the Milk...
We should get a purple colour appearing at the top of the solution. This indicates protein is present
in Milk. That is the end of experiment OB3D...
Experiment - OB5. To investigate the conversion of chemical energy in food into heat energy.
Safety goggles and gloves must be worn during this experiment.
We are going to use a cream cracker as our food source. And we are going to ignite the cream cracker...
And the chemical energy in the cream cracker, will be converted into heat energy. And will cause the
temperature of the water to rise...
Initally, the Temperature of the water is 23 oC. We will ignite the cream cracker using the bunsen burner.
As the cream cracker burns, it emits chemical energy in the form of heat energy. This energy is being
trapped by the water, and will cause the rise in temperature.
We will allow the cream cracker to completely burn itself out...
If we examine the temperature of the water in the testube, we will see it has risen from 23 oC to..
50 oC. A rise of 27 oC. This shows the conversion of chemical energy in food into heat energy.
Experiment - OB8. To investigate the action of the enzyme amylase on startch.
Safety goggles and Gloves must be worn as chemicals are involved.
Testube on the right contains startch and saliva. The one on the left contains startch and water.
Saliva contains an enzyme called amylase. And that enzyme breaks down startch into a product called...
Maltose. We will place the 2 testubes into a water bath at 37 oC for about 10 min.
We now remove the 2 testubes from the water bath and test both testubes for the presence of startch...
Using Iodine.
We add a few drops of Iodine into each testube.
The testube on the left, Iodine stays yellow / brown in colour. Indicating no startch present.
The testube on the right stains blue / back. Indicating the presence of startch.
From this experiment we can conclude that the amylase broke startch down into maltose.
Where as the other testube, which was acting as a control. The iodine stained blue / back...
indicating the presence of startch. That is the end of experiment OB8...