FST Lab 11 (Determination of starch by Iodine Test)

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 LAB-11

OBJECTIVE: 

Detection of starch by iodine test 

APPARATUS:

  • Dropper 

  • Analytical balance 

  • Test tube

  • Distilled water 

  • Iodine solution

  • sample 

THEORY:

Starch:  A carbohydrate that is the chief form of stored energy in plants, especially wheat, corn, rice, and potatoes. 

Composition of Starch: Starch is a mixture of two polymers: amylose and amylopectin. Amylose is a linear polysaccharide, and amylopectin, is a branched polysaccharide. 

What is an Iodine Test: The iodine test for starch is mainly performed to test the presence of carbohydrates. The food products which we eat include different types of carbohydrates, among which starch and sugars are the main carbohydrates found in our food products.

PROCEDURE: 

  • Take a fresh Potato which is washed, cleaned and dried.

  • Peel off the skin of the potato.

  • Cut the potato into small cubes or slices.

  • With the help of clean and dried Spatula, place the potato samples on the clean and dried porcelain tile.

  • Add 2 to 3 drops of dilute iodine solution on the potato samples.

  • Keep the slide undisturbed and observe the changes.


RESULT: 

According to the observation the food sample or the potato slice turned to blue-black on adding the iodine solution. This proves the presence of starch in the given plant source.


DISCUSSION: 

The iodine test for starch is a straightforward and widely used method to detect the presence of starch in various plant sources. In this experiment, we used a potato, which is a common food known to contain a significant amount of starch. The iodine test for starch is a straightforward and widely used method to detect the presence of starch in various plant sources. In this experiment, we used a potato, which is a common food known to contain a significant amount of starch.

In this experiment, after adding a few drops of iodine solution to the potato slices, a blue-black coloration was observed. This result is consistent with the expected outcome, confirming the presence of starch in the potato. The intensity of the color can also give a rough estimate of the starch content, with a more intense color indicating a higher concentration of starch.

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