Fats

Question 1

Lipids

Answer 1

Compounds formed by carbon, hydrogen and oxygen (hydrophobic and not soluble)
- Liquid form - Oil
- Solid form - Cheese, butter

Question 2

Functions - S

Answer 2

Storage
- Energy store
- Thermoregulation
Structural
- Biological membrane
- Insulating and protection

Question 3

Functions - Metabolic

Answer 3

• Provides energy
• Regulating and signalling
• Steroid hormone and bile acid synthesis

Question 4

Functions - Transport

Answer 4

Absorption and transport of fat-soluble vitamins

Question 5

TAG

Answer 5

Triacyl glycerol = glycerol + 3 fatty acids

Question 6

Saturated fatty acids - Animal fats

Answer 6

Single bonds
- Fatty acid chains (carbon atoms either single or double bonds)
- Every spot of the molecule contains hydrogen
- Solid @ RT

Question 7

Unsaturated fatty acids - Plant fats

Answer 7

Double bonds
- Not every molecule contains hydrogen
- Liquid @ RT

Question 8

Monounsaturated fatty acids

Answer 8

• Contains one double bond
• Olive, peanut and canola oil, avocados, nuts, pumpkin and sesame seeds

Question 9

Polyunsaturated fatty acids

Answer 9

• 2 or more double bonds
• Examples: Walnuts, flax seeds, fish, canola, sunflower, corn, soybean and flaxseed oil

Question 10

Omega-3 (n-3) fatty acids - Polyunsaturated fatty acids

Answer 10

First double bond at third carbon atom

Question 11

Omega 3 examples

Answer 11

Alpha linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic (DHA)

Question 12

Omega-6 (n-6) fatty acids - Polyunsaturated fatty acids

Answer 12

First double bond at 6th carbon atom

Question 13

Omega 6 examples

Answer 13

Linoleic acid (LA) and arachidonic acid (AA)

Question 14

Omega-9 (n-9) fatty acids - Polyunsaturated fatty acids

Answer 14

First double bond at 9th carbon atom

Question 15

Omega 9 example

Answer 15

Oleic acid

Question 16

Cis fats

Answer 16

Double bond (on the same side of the molecule) gives a bent fatty acid (oil@room temp)

Question 17

Trans fat

Answer 17

Double bond gives straight fatty acid (solid@room temp)

Question 18

How can a cis fat change to a trans fat?

Answer 18

Hydrogenation
- Food manufacturers’ use this to maintain texture and longer shelf life

Question 19

Phospholipids

Answer 19

Component of biological membranes
- 1 hydrophilic head
- 2 hydrophobic tails

Question 20

Sterols

Answer 20

Built from carbon, hydrogen and oxygen
- Atoms are arranged in a series of 4 rings with side chains
(components of cell membranes and lipoproteins)

Question 21

Essential fatty acids

Answer 21

Omega 3 fatty acids – Alpha-linolenic (ALA)
Omega 6 fatty acids – Linoleic acid (LA)
Semi-essential – EPA (eicosapentaenoic) and DHA (docosahexaenoic)

Question 22

What foods can you find alpha-linolenic?

Answer 22

Flax seeds, walnuts, tofu

Question 23

What foods can you find linoleic acid?

Answer 23

Sunflower seeds, soybean oil, pecans, brazil nuts

Question 25

Digestion and ABSORPTION - Small intestine

Answer 25

- Bile salts emulsify fats - Pancreatic lipase breaks down TAG to glycerol and fatty acids

Question 26

Digestion and absorption - Mouth

Answer 26

Lingual lipase breaks down triglycerides

Question 27

Digestion - Stomach

Answer 27

- Mixing and churning disperse food particles and fat molecules - Gastric lipase contributes to the digestion of triglycerides

Question 28

Digestion and absorption overview

Answer 28

- Lipid absorption from the small intestine * FAs, glycerol and other lipid products are incorporated in to mixed micelles and cross small intestinal wall * FA and other products reform to make TAG * TAG and other lipids (e.g. cholesterol) packed with proteins into chylomicrons (CM) – which passes into circulation * Lipoprotein lipase converts TAG to FAs and glycerol. FA enters adipocyte for storage or in muscles, FA may be used as fuel source

Question 29

Fat and health

Answer 29

CHD and cancer - Obesity has strong links to bowel, breast, kidney and oesophageal cancer

Question 30

Recommendations and guidelines

Answer 30

35% of food energy per day - 11% SFA

Question 31

Lipoprotein

Answer 31

Protein on the outside (hydrophilic), fat on the inside (hydrophobic)