Lipids

Question 1

3 classifications of fatty acid

Answer 1

Saturated fatty acids
Monounsaturated fatty acids
Polysunsaturated fatty acid

Question 2

Omega 3 fatty acids

Answer 2

• double bond between 3rd and 4th carbon atoms
• walnuts, seeds, oily fish
• lowers blood pressure and boosts brain activity

Question 3

Cis fatty acid

Answer 3

• naturally occurring
  -eg olive oil
• reduce risk of CHD
  Hydrogens are on same side of the double bond

Question 4

Trans fatty acid

Answer 4

• man made
• eg cakes, pastry’s
• increase LDL cholesterol
• hydrogens are on different side of double bond

Question 5

Properties

Answer 5

Smoke point 
Plasticity 
Hydrogenation 
Emulsion
Rancidity 
Ether

Question 6

Smoke point

Answer 6

• solid fat eg butter is heated to 30-60’C it melts
  = if heated to 200’C fat or 250’C oil the glycerol separates from the fatty acid
  = changes to acrolein which produces a blue haze and smoke
  Flash point- overheating causing vapour to spontaneously ignite and burst into flames
• occurs at 310’C fat or 325’C oil

Question 7

Plasticity

Answer 7

How solid/liquid or separable that fat is

Eg butter is hard but margarine is soft and more plastic and more user friendly when baking

Question 8

Hydrogenation

Answer 8

Hydrogen is added to unsaturated fat with nickel catalyst present in it.
- converting oil into fats and use in production margarine
= create trans fats

Question 9

Emulsion

Answer 9

Created when two liquids that don’t normally mix are forced together eg oil and vinegar
=water in oil emulsion
-eg butter 80% fat and 16% water
=oil in water emulsion
-eg milk 4% fat and 87% water

Question 10

Two types emulsion

Answer 10

Temporary emulsion- eg shaking a french dressing to mix vinegar and oil

Permanent emulsion- eg lechtin in egg yolk used as a emulsifier added to mayonnaise

Question 11

Rancidity

Answer 11

= spoilage of lipids

1. Oxidative rancidity - oxygen combines with the carbon at double bond
2. Hydroltyic rancidity- enzymes or bacteria break down fats changing them into fatty acids and glycerol

Question 12

Ether

Answer 12

Fat is soluble in ether

Question 13

Liver

Answer 13

• produces bile containing salt

- bile salts breakdown lipids to emulsifier fats

Question 14

Pancreas

Answer 14

• produces pancreatic juice containing pancreatic lipid

- this breaks lipid into 1 glycerol and 3 fatty acids

Question 15

Small intestine

Answer 15

• produces intestinal juice containing intestinal lipase

- completes digestion of fats

Question 16

Saturated fatty acid

Answer 16

• each carbon fully saturated with full quota of hydrogen atoms
• no double bonds

Question 17

Monounsaturated fatty acid

Answer 17

• reach carbon not fully saturated with full quota of hydrogen atoms
• one double bond between carbons

Question 18

Polyunsaturated fatty acid

Answer 18

• each carbon not saturated with a full quota of hydrogen atoms
• more than one double bonds occurring between carbon atoms

Question 19

Emulsifier

Answer 19

Molecule that has hydrophilic head (water loving) and a hydrophobic tail (water hating)
= when added to mixture head attaches to water and tail attaches to oil
= prevent liquid from separating
Eg lechtin in egg yolk used as emulsifier in mayonnaise