1. Food Tests Session 1

2. Learning Objectives  To identify and describe sources of the main components in food  To identify, describe and carry out food tests for starch, glucose, protein and lipids

3. Why do we need these foodstuffs?

4. Starch  It is a long chain carbohydrate  It provides energy for body processes  It can’t be absorbed by the body as the chain is to long.  It is broken down by the enzyme Amylase  Found in potatoes, rice, bread, pasta & cereals

5. Glucose  Easily absorbed into the body  Provides immediate energy for body processes  Energy dense  It is used by mitochondria in the cells in the respiration process  Found in most foodstuffs but especially fruit, bread, rice, potatoes, pasta and milk

6. Protein  Used for growth and repair  They are broken down into amino acids which are body can’t produce  Easily absorbed as amino acids  Found in meat, eggs, dairy, nuts and soya

7. Fats (Lipids)  Two different types, saturated and un- saturated fats  Unsaturated fats “good” for your heart and cholesterol levels  Saturated fats can raise cholesterol levels and lead to heart disease.  Broken down into fatty acids and glycerols  Contain energy which is released slowlt compared to Glucose  Found in foods such as Oils, butter, cheese, walnuts, fried foods, chicken skin etc.

8. Food tests

9.  There are 4 food tests arranged around the classroom  You will get 15 minutes at each station to conduct the test on a foodstuff containing the component you are looking for  Follow the instructions on the handouts to conduct the tests  You will need to record your observations and results for future work (Assignment)

10. Results

11. Starch Test  Positive is shown by the iodine turning dark bluey/black colour  Negative is shown by the iodine remaining a browny colour

12. Glucose test  Positive is indicated by Benedicts solution turning reddy/brown brick colour although any colour change indicates presence  Negative is indicated by Benedicts solution remaining blue in colour

13. Protein Test  Positive result indicated by Biurets test going a violet/purple colour  Negative result indicated by Biurets test remaining blue in colour

14. Fats (Lipids) Test  Positive result is indicated by permanent grease spot on paper  Negative result is indicated by the absence of a permanent grease spot on paper