Food Tests Part 1 (SC) PDF

Don’t do Q11 and Q15 Wat er Starter Carb Lipids/ Fa ohyd ts Fruit rates...

Don’t do Q11 and Q15 Wat er Starter Carb Lipids/ Fa ohyd ts Fruit rates on Milk p at i on sti C Red Prot m eat ein Vitamin C Vitamin B No Vi ta Yogh m Fibre u in rt D L2- Food Tests Part 1 C system Learning Objectives Describe the roles of the main food groups in the body. Describe how to carry out food tests for Starch, Proteins and Fats. Carry out food tests for starch Proteins and Fats The 7 food groups Our bodies require 7 different food groups to stay healthy. We must make sure our diet contains the correct amount of each of the following: - Carbohydrates - Proteins - Fats - Vitamins - Minerals - Fibre - Water Carbohydrates Source of energy, for example glucose is important for respiration.  Proteins are important for the Proteins growth and repair of cells/tissues. They are also important for hormones, enzymes and antibodies. Fats/ Lipids Fats/lipids can be used as a source of energy and insulation. Fibre Fibre cannot be digested by the body. It is made up of plant cell walls (cellulose). It is very important for encouraging a smooth passage of food through the Alimentary canal in the digestive system – otherwise we get constipation! Minerals Essential for the body to beable to use other nutrients efficiently. Only needed in small amounts. Iron Calcium Vitamins Essential for the body to beable to use other nutrients efficiently. Only needed in small amounts. Vitamin C Vitamin D Water Essential for hydration Food tests Today you will be learning how to test food for some different food groups: Carbohydrates: Carbohydrates: proteins lipids starch Glucose (a reducing sugar) Bread Honey Chicken butter Potatoes Syrup Eggs oils pasta Fruit squash Beans cream lentils A quick intro to Carbohydrates There are lots of different types of carbohydrates Eg: STARCH GLUCOSE (A complex sugar that is a large (A simple sugar that is a small molecule) molecule) We call glucose a reducing sugar Food Test 1: Starch If NO starch present, the iodine solution stays orange/brown Iodine solution is orange/brown to start If starch IS present, the iodine solution turns BLUE/BLACK Testing for Starch You will need: - A spotting tile - A pipette - Iodine Solution (orange brown) 1. Place a bit of food in the well of the spotting tile (you may need to crush it) 2. Add a few drops of iodine solution. 3. Observe the colour change. (if it stays orange-brown there is no starch present. If it turns blue-black, there is starch present). Food Test 2: Proteins If NO Proteins present, the biuret solution stays blue biuret solution is blue to start If protein IS present, the biuret solution turns lilac/purple Testing for Proteins You will need: - A large test tube (boiling tube) - A pipette - Pestle and mortar - Biuret solution (blue) 1. Crush some food in a pestle and mortar and place in a boiling tube. 2. Add some water (about 1-2cm in depth) 3. Add some drops of Biuret solution. (if it stays blue there is no protein present. If it turns purple (lilac), there is protein present) Food Test 3: Fats If NO fat present, the ethanol stays colourless Ethanol is COLOURLESS to start If fats are present, the ethanol solution turns CLOUDY WHITE Testing for Fats/lipids You will need: - 2 large test tube - A pipette - Pestle and mortar - Ethanol 1. Crush some food in a pestle and mortar and place in a boiling tube. 2. Add some ethanol (about 1-2cm in depth). Mix 3. Add some water (about 1-2cm in depth) to a SEPARATE BOILING TUBE. 4. Carefully pour some of the ethanol from boiling tube number 1 into the water. (If it turns milky/cloudy white, there is fat present) Food Test Summary Molecule tested for Reagent Used in Test What colour is it to start What colour is a positive with? result? Starch Iodine solution Orange- brown Blue-black (a carbohydrate) Protein Biuret solution Blue Lilac/purple Fat/lipids Ethanol Colourless milky/cloudy  What am I? 1. I am needed for growth and repair of cells 2. I am a component of a balanced diet that prevents constipation 3. I am a component that provides energy. 4. I am needed in the diet as I am required for metabolic reactions in cells. 5. I am the solution used to test for starch 6. I am the solution used to test for proteins 7. I am the colour change for a ‘positive test’ for proteins. 8. I am the solution needed to test for fats 9. I am the colour change for a ‘positive test’ for starch 10. I would be observed if there was a positive test for fats