Nutrients

1. Nutrients B4: Nutrition

2. Carbohydrates Contain the elements carbon (C), hydrogen (H) and oxygen (O) Simple sugars (glucose) consist of 6 C atoms in a ring shape Complex sugars (maltose, sucrose and lactose) are 2 molecules of simple sugars chemically bonded together– soluble and sweet Complex carbohydrates are made of many simple sugars bonded together (starch from plants and glycogen in animals) – insoluble and not sweet

3. Carbohydrates • Found in foods like rice, potatoes, bread, yams, sugar and honey • Provide a ready source of energy • Simple sugars can be absorbed immediately into the blood • Complex carbs need to be broken down by enzymes (i.e. amylase) before they are able to be absorbed • The test for starch in food involves the use of iodine • When starch is present, iodine turns blue-black in colour • When there is no starch present, iodine stays orange-brown • The test for reducing sugars uses Benedict’s solution • When heated gently, Benedict’s will turn green-yellow-orange and then red when sugar is present • In the absence of sugar, Benedict’s will stay blue when heated

4. Proteins • Contain the elements carbon (C), hydrogen (H), oxygen (O), nitrogen (N) and sometimes sulfur (S) • Long-chain molecules of amino acids folded into different shapes (depending on function) • Different order of amino acids (there are 21) will give different proteins • Some proteins are soluble in water (haemoglobin, enzymes, antibodies and some hormones) • Some proteins are insoluble (keratin) • Proteins are needed for the growth and repair of cells and tissues, and for the formation of cell membranes

5. Proteins • When food protein is digested, the amino acids can be reused by cells to produce new proteins • Found in foods such as meat, fish, milk and nuts • Use biuret solution to test for protein • When protein is present, the biuret solution turns purple, violet or lilac in colour • When there is no protein present, the biuret solution stays blue

6. Fats • Contain the elements carbon (C), hydrogen (H) and oxygen (O) • Each fat molecule is made up of one molecule of glycerol with 3 attached molecules of fatty acids • There are different types of fatty acids allowing the formation of different fats • Fats are used for thermal insulation, energy storage in the body, and buoyancy in water (whale blubber) • Stored around the heart and kidneys , and under the skin • 1g of fat can release twice as much energy as 1g of protein or carbohydrate

7. Fats • Good sources of fat include foods such as butter, nuts, cheese, and fish & animal fat • Fats do not dissolve in water, but they are soluble in ethanol • A cloudy-white emulsion is formed when fat dissolved in ethanol is added to water • If there is no fat, the ethanol will remain clear