B4: NUTRITION Nutrients

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

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

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

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

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

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