Experiment 25

Objective: Extracting Starch from Potatoes

Introduction:

This experiment demonstrates how to extract and isolate starch from potatoes, highlighting the presence of starch in plants. Starch is a common, colorless, and tasteless compound found in seeds and tubers. It is used for various purposes, including thickening food, manufacturing textiles and paper, and even as a mold for jelly beans and wine gums.

Required Materials:

●       5 large potatoes

●       Peeler

●       Grater

●       2 bowls

●       Water

●       Sieve

Procedure:

1.    Peel the potatoes to remove the skin.

2.    Grate the potatoes into one of the bowls.

3.    Submerge the grated potatoes in water by filling the bowl until the potatoes are completely covered.

4.    Squeeze the potatoes with your fingers for several minutes.

5.    Wait for about 30 minutes, then repeat the squeezing process from step 4.

6.    Strain the mixture: Pour the mixture through a sieve into the second bowl, allowing the cloudy water to pass through while catching the grated potatoes in the sieve.

7. Dry the starch: Place the bowl containing the cloudy water in a sunny place and allow the water to evaporate. You will be left with a white powder, which is the extracted starch.

Observations:

After the water evaporates, a white powdery substance—starch—will remain in the bowl. Starch is a carbohydrate found in many plants, serving as an energy storage compound. When consumed, starch is converted into sugar by enzymes in saliva, providing energy to the body.

Questions:

1.    What do you think is the purpose of squeezing the potatoes? Squeezing the potatoes helps release the starch into the water by breaking down the cell structure of the potato.

2.    Why do you suppose it's best to let the potatoes soak for 30 minutes before squeezing them again? Soaking allows more starch to separate from the potato fibers, making the extraction more efficient when you squeeze them again.

3.    Can you think of any other plant or vegetable where you can apply a similar process to extract starch? A similar process can be applied to corn, cassava, or rice to extract starch