Lipids

Question 1

Saturated fatty acids

Answer 1

Each carbon atom saturated with hydrogen
No double bonds present
Solid at room temp
Animal sources
Butyric acid in butter

Question 2

Monounsaturated fatty acids

Answer 2

Not every carbon atom saturated with hydrogen
One double bond present
Soft or liquid at room temp
Plant sources
Oleic acid in olive oil

Question 3

Polyunsaturated fatty acids

Answer 3

Not every carbon atom saturated with hydrogen
More than one double bond present
Soft or liquid at room temp
Plant sources
Linolenic acid in veg oil

Question 4

Two essential fatty acids

Answer 4

Linoleic acid in corn oil
Linolenic acid in veg oil

Question 5

Essential fatty acid functions

Answer 5

Builds cell membranes
Raises HDL lowers LDL
Prevents CHD

Question 6

Difference between cis and trans fatty acids

Answer 6

Cis have hydrogen saturated above carbon atom
Trans have one hydrogen above and one below
Cis are unsaturated

Question 7

When do cis fatty acids change to trans fatty acids

Answer 7

During Hydrogenation

Question 8

Sources of omega-3

Answer 8

Oily fish, fish oils, nuts, seeds

Question 9

Functions of omega-3

Answer 9

Reduces risk of CHD, lowers LDLs, raises HDLs
Decreases blood viscosity, prevents clots or blockages in the coronary artery
AIDS fœtal brain development
Improves memory and cognitive functioning through life

Question 10

7 properties of lipids

Answer 10

Solubility, absorbs flavour, affected by heat, emulsions, hydrogenation, rancidity, plasticity

Question 11

Solubility

Answer 11

Insoluble in water
Soluble in solvents eg ether/benzene

Question 12

Absorbs flavour

Answer 12

Eg chilli oil, garlic butter

Question 13

Affected by heat

Answer 13

Melting point: 30°-40°C
Smoke point: decompose to glycerol + 3 fatty acids, acrid smelling compound present(acrolein), blue haze emerges, solid fats@200° oils@250°
Flash point: decomposition continues, spontaneously burst into flames, solid fats@310° oils@325°

Question 14

Emulsions

Answer 14

Two immiscible liquids forces together creates an emulsion
Permanent emulsion: oil and water forced together with an emulsifier
Eg, oil + vinegar + egg yolk = mayo
Hydrophilic head + hydrophobic tail
Eg lecithin in egg yolk

Question 15

Hydrogenation

Answer 15

Hydrogen forced through double bond of unsaturated fatty acids
In presence of a nickel catalyst
Eg oil hydrogenised to margarine
Cis fatty acids turned fully saturated trans fatty acid

Question 16

Rancidity

Answer 16

Oxidative : oxygen forced through double bonds of cis fatty acid. Eg Oil solidifying on pan
Hydrolytic : enzymes and bacteria react with lipid. Most common in freezers when enzymes are not destroyed. Result-triglycerides breaking down and flavour altered

Question 17

Plasticity

Answer 17

Describes how soft, pliable and malleable a fat is at a given temp
Determined by degree of saturation
More saturated fatty acids present, more solid
Eg butter solid at room temp, margarine soft

Question 18

Absorption

Answer 18

Occurs after digestion in lacteals in villi in small intestine

Question 19

Utilisation

Answer 19

Oxidized in liver and muscles
Produces heat and energy, source of fat soluble vit, forms cell membranes, provide essential fatty acids

Excess stored in adipose tissue
Insulation, energy reserve, protects organs

Question 20

Energy value

Answer 20

1g = 9kcal/37kJ

Question 21

Maximin intake

Answer 21

70g