A class practical on testing the presence of starch in food was performed using Foldscope by students of 6th semester.
Requirements: Potato tuber, razor blade, cover slip, water, iodine solution, microscope, blotting paper, foldscope
Principle: Iodine reacts with starch and changes its colour to blue-black
- Cut a thin section of a potato tube by means of razor blade or gently scrap out a few potato cells
- Place them in a drop of water over a glass slide.
- Observe under microscope. The cells of tuber are seen full of starch grains.
- Pour a drop of iodine solution at one end of the mount and drain out the water from other end by means of filter paper.
- Observe the change in colour.
Observations: The starch grains are seen to change colour to blue – black