Major Nutrients and Testing Methods

Major Nutrients in Food

• Primary nutrients include carbohydrates, proteins, fats, vitamins, and minerals.
• Dietary fibers and water are also essential parts of food.

Testing for Starch

• Dilute iodine solution: made by adding iodine tincture to water.
• Copper sulphate solution: prepared by dissolving 2 g in 100 mL of water.
• For testing, apply 2-3 drops of iodine solution to the food sample.
• Color change to blue-black indicates the presence of starch.

Testing for Proteins

• For solid food, grind into a powder before testing.
• Combine powdered food with distilled water in a test tube and shake.
• Add two drops each of sodium hydroxide and copper sulphate solutions.
• A purplish color confirms the presence of proteins.

Testing for Fats

• Similarly, powder solid food before testing.
• Mix powdered food with 2-3 mL of ethanol in a test tube and shake.
• Decant the clear solution and add 2-3 mL of water, then gently shake.
• Formation of whitish globules on the water's surface indicates the presence of fats.

Safety Precautions

• Avoid tasting or eating any chemicals during testing.
• Exercise caution while conducting experiments to ensure safety.