Q1.How will you check the presence …

1.Test the food item with a few drops of iodine solution on the food sample and observe. We can see that the part of food with iodine solution turns to a blue-black color. A blue-black color indicates the presence of starch.

2.If the substance turns the paper translucent (or slightly see-through), it contains fat.

3.The presence of proteins in food is tested in the following way:

• Step i - The food should be in either liquid form or in suspension form (used for solid food material)
• Step ii - Preparation of suspension -food material is crushed in mortar -pestle using water.
• Step iii - Take little sample in a test tube, to it add a few drops of oil caustic soda solution till the mixture clears.
• Step iv - Then add a few drops of copper sulphate solution and shake it well.
• Step v - Carefully heat the test tube over a flame. Hold the damp litmus paper over the mouth of the test tube and observe any colour change.

Presence of violet colour indicates the presence of protein in the food sample.