Unit 4 : Food Chemistry - Lipids

Question 1

Based on the chemical structure, what are lipids broadly classified as ?

Answer 1

• Triglycerides
• Phospholipids
• Sterols

Question 1

Describe the structure of triglycerides

Answer 1

• it is composed of three fatty acids esterified to a glycerol molecule

Question 2

How many carbons are in short , medium and long chain fatty acids ?

Answer 2

• Short Chain : less than or equal to 10 carbons
• Medium Chain : 12 - 14 carbons
• Long Chain ; more than or equal to 16 carbons

Question 3

How are cis and trans fatty acids identified and are they solid, liquid or gas at room temperature ?

Answer 3

• They are cis bonds when there is a bend in the double bond of carbon and they are liquid because they aren’t packed closely
• Trans fatty acids have no bend in the carbon double bond and it is solid at room temperature

Question 4

What can high intake of saturated and trans fat intake lead to ?

Answer 4

• Increased risk of heart disease

Question 5

Describe the structure of phospholipids

Answer 5

• Two fatty acids and phosphorus containing molecule attached to glycerol molecule

Question 6

Describe the structure of sterols

Answer 6

• class of lipids containing a common steroid core of a fused four ring structure with a hydrocarbon side chain and alcohol group

Question 7

What can high intake of cholesterol lead to ?

Answer 7

• May increase risk of heart disease

Question 8

How are lipids helpful in frying ?

Answer 8

• Most oils and fats can be heated to temp higher than 160 degrees celsius.
• Since oils and fats can be heated to a much higher temp than water food cooks much faster when fried in hot oil or fat

Question 9

How are lipids helpful in terms of plasticity ?

Answer 9

• Plasticity is the ability of a solid material to undergo permanent deformation and solid fats can do this
• they are used in baking and are helpful in providing textures

Question 10

How are lipids helpful in flavouring?

Answer 10

• Fat masks undesirable flavours such as bitterness

Question 11

How are lipids helpful in tenderness of a food item?

Answer 11

• Meats contain two types of fat, cover and marbled fat.
• the higher the marbled fat the more tender the meat is
• the cover fat has little effect on tenderness but more on flavour