- Take small quantity of food items or raw ingredients boiled chickpeas , or any other lentil
- If food is solid, make a paste or a powder out of it.
- Put this paste or powder in a clean test tube.
- Add a few drops of water and shake well.
- With a dropper add 2 drops of copper sulfate and 10 drops of caustic soda solution.
- Shake well and leave the test tube for a few minutes
- The ingredients in the test tube changes its color.
- If the color changes into violet , it indicates the presence of proteins i n the food items.