Explain different food tests used to identify nutrients.
Different food tests are used to identify the presence of specific nutrients in food samples. These tests are commonly performed in school science laboratories and are based on characteristic colour changes or physical observations.
| Food Test | Nutrient Tested | Reagent Used | Positive Result |
|---|---|---|---|
| Iodine Test | Starch | Iodine solution | The solution turns blue-black if starch is present. |
| Biuret Test | Proteins | Copper sulphate solution and sodium hydroxide solution | The solution turns violet or purple if proteins are present. |
| Grease Spot Test (Translucent Paper Test) | Fats | Clean paper (no chemical reagent required) | A permanent translucent or greasy patch appears on the paper if fats are present. |
These food tests help identify important nutrients in foods such as rice, potatoes, milk, eggs, pulses, nuts, and cooking oils. They are simple, reliable experiments that help students understand the nutritional composition of different foods.