Testing foods for starch, protein and fat
Test twelve everyday foods, from rice and atta to egg white and ghee, with iodine, copper sulphate and a piece of paper, then sort them by the nutrient they are mostly made of.
Core concept
In short: Test foods with drops and paper to find starch, protein and fat.
Iodine turns starch blue-black, copper sulphate with caustic soda turns protein violet, and fat leaves a see-through oily spot on paper; most foods are mostly one nutrient
Topic: Food and nutrition
Food gives us nutrient: Something in food that the body needs to grow and stay healthy, like protein or vitamins. All key words. Three of them can be found with simple tests. Starch, a carbohydrate that gives us energy: What is needed to make things move, heat up, light up or grow. All key words, turns blue-black when a few drops of dilute iodine solution are put on it. protein: A nutrient for growth and repair, found in beans, eggs, milk and meat. All key words, which builds the body, turns violet when two drops of copper sulphate solution and ten drops of caustic soda solution are added (this is how NCERT does it). Fat, which stores energy, leaves a see-through oily spot when the food is rubbed on paper and the paper is held up to the light. Most foods are mostly one nutrient, so the tests tell us which group a food belongs to.
What you will learn
- Test a food for starch with iodine.
- Test a food for protein with copper sulphate and caustic soda.
- Test a food for fat with the paper test.
- Group foods by the nutrient they are mostly made of.
Before you start
- Know that food gives us nutrients.
Materials
- Small pieces of rice, potato, bread, egg white, fish, butter and oil
- A sheet of plain paper
Equipment
- Dilute iodine solution, copper sulphate solution and caustic soda solution, with droppers
- Test tubes or small dishes
Procedure
- Pick a food card and try the iodine, copper sulphate and paper tests.
- Do this for at least eight foods.
- Sort every food into starch, protein or fat.