Starter Look at food labels Why is it

Starter • Look at food labels • Why is it useful to put the ingredients and nutritional value of food on labels? • What is a food scientist? • What is the Foods Standards Agency?

Food Tests Learning objectives: All students must: • Carry out food tests for starch, sugars, protein and fat. Most students should: • Describe why food labels are important. Some students could: • Describe the food tests

Video • How do scientists come up with food labels? • Watch the video and think about: – What amounts of energy and nutrients should we be eating? – Why is it important to test foods and create food labels?

Testing for Starch • Add a few drops of orange iodine solution to your food sample. • If starch is present the sample will turn blue black. Testing for Glucose • Add some water to your food in a test tube to make a solution. • Add an equal volume of blue Benedict’s solution and heat in a water bath. • If glucose is present the solution will turn green , orange or brick red depending on how much glucose is present. Testing for Protein • Add some water to your food sample in a test tube and shake it. • Then add a few drops of blue biuret solution. • If protein is present the solution will turn lilac or blue depending on how much protein is present. Testing for Fats • Mix the food sample with a third of a tube of ethanol and shake well. • Filter the mixture to remove any solids. • Add some clean water to the filtrate. • If fat is present a white emulsion will form and float.

Complete Table Testing foods for nutrients. FOOD STARCH TEST observation A B C D conclusion GLUCOSE TEST observation conclusion PROTEIN TEST Observation conclusion FAT TEST observation conclusion

Plenary • Identify any risks associated with the practical methods for testing foods in the lab. • Explain how risks can be minimised. • Imagine students do not have a water bath and are considering heating ethanol solution using a bunsen burner. • Evaluate the risk associated with this method. • Should this risk be taken.

TASK: Food Test Summary Divide a piece of paper into quarters. Describe the method for each nutrient in a different quarter of your paper. Include drawings to help you remember! – Test For Starch – Test For Glucose – Test For Protein – Test For Fats