1. Food Tests 2

2. Learning Objectives  To identify vitamin C and ions present in foods  To describe the role of vitamins and minerals in the diet  To explain the roles of Glucose, Lipids and proteins in the diet

3. Food Tests

4. Vitamin C  Required to protect cells from damage caused during respiration  Also required for the production of collagen in our bodies  Found in citrus fruits, root vegetables and fortified foods e.g. breakfast cereals  Can be taken as a supplement  Lack of Vitamin C leads to disease called Scurvy  Why are Britons called “Limeys”?

5.  To test for vitamin C we use DCPIP  DCPIP changes colour in the presence of acid from blue to red  When Vitamin C is present, it becomes colourless.  Vitamin C is Ascorbic acid so this is why we get the colour change  However other chemicals in food can also do the same thing to DCPIP

6. Flame Tests for Ions  We also need minerals in our diet.  These include Calcium, Iron, Zinc, Potassium, Copper, Magnesium, Manganese, Molybdenum, Silicon, Chromium and others  These minerals are normally part of a compound i.e. Sodium in Sodium Chloride  We normally can get all our minerals from our diet

7.  We test for these minerals using flame tests  Each elements has a characteristic colour when it is placed in a flame  The colours never change!!  On the next page there are pictures showing the colours of each of the minerals

9. Pop Quiz (10 minutes)  How do we test for fats?  How do we test for reducing sugars?  How do we test for proteins?  How do we test for starch?  Why do we need glucose?  Why do we need proteins?  Where do we breakdown starch?  What enzyme breaks down fats?

10. Role of nutrients in our body

11.  Each of the nutrients we have looked at so far has a specific role in the body  Without these nutrients our bodies do not function correctly  In cases where there is a severe lack of a nutrient it can lead to disease states

12. Glucose (C 6 H 12 O 6 )  Its role is to provide energy for the body  It is used in the respiration process that takes places within mitochondria  Its entry into the cell is facilitated by insulin, the hormone that regulates blood glucose levels  Excess glucose is converted into glycogen in the liver  This glycogen can be converted back into glucose when blood sugar levels dip below a certain level (4- 7mmol/l)  It is recommended that you eat complex sugars such as those found in fruit and vegetables rather than simple sugars like those found in sweets and sugary drinks

13. Lipids  More correctly known as triglycerides as they contain three fatty acid chains attached to a glycerol backbone. If they are the same acid it is known as a simple triglyceride. If it has different acids it is a mixed triglyceride  They are used for energy storage and also as a signaling molecule. They also make up the lipid bilayer of the cell membrane

15. Proteins  Broken down into amino acids by proteases  Amino acids then used in the ribosomes inside the cells to produce proteins required for growth and repair  Most important in adolescence, childhood and pregnancy. Why?

16.  Classified as either essential or non- essential. Essential amino acids are those which the body cannot produce itself whereas non-essential can be produced  Conditional amino acids are not normally made by the body except in times of stress or illness  There are 20 amino acids which have similar structures but different side chains

17. Task

18.  What are the disease states associated with a lack of Glucose? Fats? Proteins?  What might cause this lack of nutrients?  How can we treat them?  How long can we survive without treatment?