Food Tests D. Crowley, 2007 Food Tests To know how to test for starch, sugar, protein and fat
Wednesday, April 26, 2017 Food Tests To know how to test for starch, sugar, protein and fat Spaghetti Bolognese Is spaghetti Bolognese a balanced meal?
Spaghetti Bolognese contains fat (oil); protein (meat) and carbohydrate (spaghetti) But it lacks minerals, vitamins and fibre To make this balanced, we need to add both minerals, vitamins and fibre - e.g. adding mushrooms, fresh tomatoes etc and drinking with a glass of fresh juice or milk would make it a great (and balanced) meal! Food Tests There are a variety of tests we can carry out to sample what is contained within a food It is your job to carry out the tests, and identify what is contained within the food examples Watch the demo of the food tests For the food tests (except for fat) we must first prepare a food sample This is achieved by: - Crushing some food in a pestle and mortar Adding a spatula-full to a boiling tube Adding 5cm3 of distilled water and stir Bringing to boil and simmering for 1 minute (using a water bath) Cooling and adding the test reagent Starch Test Iodine tests for starch - it turns blue / black
Add some drops of brown iodine solution to the food If it contains starch, the iodine will turn blue / black Simple Sugars Test Benedicts test for simple sugars - produces an orange precipitate Add the blue Benedicts solution to the food Heat using a water bath (for safety) An orange precipitate will form if simple sugars are present Protein Test Biuret test for protein - turns copper sulphate purple
Add some sodium hydroxide (NaOH) to the food, and shake Add some weak copper sulphate (CuSO4) If the pale blue colour turns purple, protein is present Fat Test Rub a food sample onto a piece of paper and leave to dry
If fat is present, the paper will have a translucent stain round the sample, when held to the light Complete The Risk Assessment
Complete the risk assessment for the food tests, then collect a sheet and get ready to carry out the experiments Experiment Predict, then carry out your experiment, using the sheet, testing the foods to see what they contain Each food needs to be tested for starch; simple sugar; protein; and fat Record your results Food Starch Protein Fat Glucose Predict Result Food A Food B Food C etc