Lipids 2.0

Question 1

Are lipids a macronutrient or a micronutrient?

Answer 1

Macronutrient

Question 2

What are the properties of lipids?

Answer 2

Plasticy, Solubility, Absorb flavours, Rancidity, Hydrogenation, Emulsification, Stabiliser

Question 3

What is the difference between a fat and oil?

Answer 3

Fats are solid at room temperature, e.g., butter; oils are liquid at room temperature, e.g., olive oil.

Question 4

What are the elements of lipids?

Answer 4

Carbon, hydrogen, oxygen

Question 5

What is the basic structure of lipids?

Answer 5

Triglyceride: glycerol and 3 fatty acids

Question 6

What are the two groups of lipids?

Answer 6

Saturated & unsaturated

Question 7

What are examples of saturated fats?

Answer 7

Butter, Cream, Bacon, Milk, Cheese

Question 8

What are examples of unsaturated fats?

Answer 8

Salmon, Nuts, Seeds, Olive oil, Avocado

Question 9

What are the functions of fat?

Answer 9

1g of fat = 9 kcal, Protects vital organs (e.g., kidneys), Insulates body (adipose tissue), Provides fat-soluble vitamins A, D, E & K.

Question 10

What can too much fat cause?

Answer 10

CHD, Obesity, Type 2 diabetes

Question 11

What is the maximum lipid consumption?

Answer 11

Less than 35% of all energy.

Question 12

What are four ways to reduce fat?

Answer 12

Don’t fry, steam or grill foods; Don’t add butter to potatoes; Use low-fat milk over full-fat milk; Don’t add cream to desserts.

Question 13

What are the three types of fatty acids?

Answer 13

Saturated FA, Monounsaturated FA, Polyunsaturated FA

Question 14

What characterizes saturated fatty acids?

Answer 14

No double bonds between carbons, All carbons are saturated with hydrogen, Solid at room temperature (18 degrees), e.g., butyric acid in butter.

Question 15

What characterizes monounsaturated fatty acids?

Answer 15

Contain one double bond between carbons, Not all carbons are saturated with hydrogen, Liquid at room temperature (18 degrees), e.g., oleic acid in olive oil.

Question 16

What characterizes polyunsaturated fatty acids?

Answer 16

Contain 2 or more double bonds between carbons, Carbons not fully saturated with hydrogens, Liquid at room temperature (18 degrees), e.g., linoleic acid in nuts.

Question 17

What are cis fatty acids?

Answer 17

Hydrogens are both above or below the double bond in the carbon chain.

Sources: Oily fish (e.g., salmon), olive oil & seeds. Healthy effects: Lowers LDL cholesterol, reducing CHD & increases HDL cholesterol.

Question 18

What are trans fatty acids?

Answer 18

Hydrogens are on opposite sides of the double bond in the carbon chain.

Sources: Chips, biscuits & donuts. Healthy effect: Raises LDL cholesterol, increasing risk of CHD & lowers HDL cholesterol.

Question 19

What are essential fatty acids?

Answer 19

Cannot be made by the body and must be obtained from food, e.g., linoleic acid.

Question 20

What are omega 3 fatty acids?

Answer 20

1st double bond is between the 3rd and 4th carbon.

Sources: Salmon & cod liver oil. Function: Lowers LDL cholesterol which reduces risk of CHD & aids brain development of fetus during pregnancy.

Question 21

What is the solubility property of lipids?

Answer 21

Lipids won’t dissolve in water but dissolve in alcohol, e.g., cream in whisky.

Question 22

How do lipids absorb flavours?

Answer 22

Lipids can absorb flavours easily.

Example: Garlic butter.

Question 23

What are the effects of heating lipids?

Answer 23

Melting point, Smoke point, Flash point

Question 24

What is the melting point of fats?

Answer 24

Solid fats melt & turn to liquid between 30-40 degrees.

Question 25

What is the smoke point of fats?

Answer 25

Overheating causes lipids to break down, glycerol splits from 3 fatty acids, creating a blue haze. Occurs at 200 degrees in fats.

Question 26

What is the flash point of fats?

Answer 26

Blue haze bursts into flames. Occurs at 310 degrees in fats.

Question 27

What is emulsification?

Answer 27

Created when 2 immiscible liquids are forced together. ## Footnote Example: Temporary emulsion (vinegar & oil) separates; Permanent emulsion (oil & water with emulsifier) does not separate (e.g., mayonnaise).

Question 28

What is an emulsifier?

Answer 28

Forces oil & water together as it has a hydrophobic tail which attaches to the oil & a hydrophilic head which attaches to the water. ## Footnote Example: Lecithin in egg yolk for mayo.

Question 29

What is a stabiliser?

Answer 29

Maintains emulsions & prevents oil & water from separating. ## Footnote Example: Gelatin stabilises ice cream.

Question 30

What is hydrogenation?

Answer 30

Hydrogen gas is added to unsaturated fatty acid (oil) and changes it to semi-solid saturated fat. ## Footnote Example: Production of margarine.

Question 31

What is rancidity?

Answer 31

Oxidative rancidity: Oxygen combines with double bond in unsaturated fat causing unpleasant smell & taste. Hydrolytic rancidity: Lipase breaks down lipids into glycerol & 3 fatty acids causing unpleasant smell & taste.

Question 32

What is plasticity in fats?

Answer 32

Describes how hard (butter) or pliable (margarine) a fat is at a given temperature. ## Footnote Example: Margarine is useful for creaming queen cakes.

Question 33

What are the biological functions of lipids?

Answer 33

Provides fat-soluble vitamins A, D, E & K, 1g of fat = 9 kcal, Protects delicate organs (e.g., kidneys).

Question 34

How are digested lipids absorbed?

Answer 34

Digested glycerol & fatty acids pass into villi & go into lacteals, travel in the lymph system & enter the bloodstream through the subclavian vein, then go into the liver to be oxidized.

Question 35

What is LDL cholesterol?

Answer 35

Bad cholesterol that builds up in the arteries wall, narrowing them and increasing CHD. ## Footnote Example: Butter, cream, cheese.

Question 36

What is HDL cholesterol?

Answer 36

Good cholesterol that reduces LDL cholesterol build-up in the arteries, reducing CHD. ## Footnote Example: Olive oil & oily fish.