Nutrition and Food Tests

Nutrition and Food Tests

Nutrition and Food

  • Nutrition is the process by which organisms obtain and use food.
  • Nutrients are substances that an organism needs for growth, repair, and normal metabolism. These include carbohydrates, proteins, fats (lipids), vitamins, minerals, and water.
  • Humans require a balanced diet that includes the right proportions of each type of nutrient. Too much or too little of certain nutrients can lead to health problems.


  • Carbohydrates are made up of units of sugar and can be divided into three main types: monosaccharides, disaccharides, and polysaccharides.
  • Monosaccharides are single sugar units, for example, glucose and fructose.
  • Disaccharides consist of two sugar units, for example, sucrose (table sugar) and lactose.
  • Polysaccharides consist of many sugar units and include starch and dietary fibre.


  • Proteins are large molecules made up of chains of amino acids.
  • They are essential for growth, repair, and normal function of the body.
  • The body can synthesize most amino acids, but there are nine ‘essential’ amino acids that must be obtained from the diet.
  • Foods rich in protein include meat, eggs, dairy, legumes, and soy products.

Fats (Lipids)

  • Fats are a source of energy and are essential for certain body functions.
  • They can be categorized as saturated (mostly in animal-based foods) and unsaturated (mostly in plant-based foods and fish).
  • The body also needs small amounts of ‘essential’ fatty acids from the diet, which it cannot synthesize itself.

Vitamins and Minerals

  • Vitamins and minerals are needed in small amounts for various body functions.
  • Most vitamins cannot be synthesized by the body and must be obtained from the diet.
  • Common examples include Vitamin C (for tissue repair and immune function) and calcium (for healthy bones and teeth).

Food Tests

  • Understanding the nutritional content of food is important and can be determined by various tests.
  • Starch test: This involves adding iodine solution to the food sample. If starch is present, the sample will turn blue-black.
  • Sugar test: Adding Benedict’s solution to the food and heating it; if sugar is present, the solution will change from blue to green, yellow, or brick-red.
  • Protein test: Adding biuret solution to the food sample; if protein is present, the solution will change to lilac or purple.
  • Fat test: Rubbing the food on a piece of paper; if fat is present, the paper will become translucent.