Test for the presence of starch (LC 2026) (Leaving Cert Biology): Revision Notes

Test for the presence of starch

Background:

Starch is an energy storage polysaccharide found in plants. Polysaccharides consist of many (more than two) monosaccharides joined together. Another polysaccharide in plants is cellulose, which plays a structural role in the cell wall.

Method:

1. Place food sample in a test tube. Place distilled water in another test tube (control).
2. Add iodine to sample.
3. Record colour change.
4. Repeat for control sample which is distilled water.

Result:

Iodine will turn from brown to blue-black if starch is present. Control remains brown.