Unit 2 - B. Triglycerides

Question 1

Triglycerides

Answer 1

• largest class of lipids
• more than 90% of the fat consumed daily by humans is in the form of triglycerides
• mainly located in cytoplasm of adipose cells
• major role = storage of energy in form of fatty acids
• glycerol + 3 fatty acids => triglyceride + H2O (esterification/dehydration)

Question 2

Simple Triglyceride

Answer 2

• all three fatty acids are the same

Ex: Tristearin

Question 3

Mixed Triglyceride

Answer 3

• mixture of fatty acids (all three are not the same)

Ex: Glyceryl oleo-lauro-stearate

Question 4

Fats

Answer 4

• complex mixtures of mixed triglycerides that are solid at room temperature
• from animal sources
• generally have a greater % of saturated fatty acids and therefore have a higher melting point than oils

Question 5

Oils

Answer 5

• complex mixtures of mixed triglycerides that are liquid at room temperature
• from plant sources

Question 6

Hydrogenation

Answer 6

• adding H2 takes away a double bond
• converts oil to ‘fat-like’ substance = semi-solid
• typically not all double bonds are hydrogenated; this would result in a brittle product

Question 7

Trans Fatty Acids

Answer 7

• some oils are hydrogenated to increase self-life (margarine and shortening) creating trans fatty acids
• behave like saturated F.A
• increases triglycerides and LDL cholesterol
• decreasees HDL cholesterol
• american heart association recommend consuming less than 1%

Question 8

Hydrolysis

Answer 8

• breaking down of triglyceride to glycerol + 3 fatty acids
• Lab = uses HCl + heat -> glycerol + 3 fatty acids
• Digestion = pancreatic lipase enzymes -> monoglyceride + 2 fatty acid because it can only break primary ester linkages (1&3)
• removal of F.A. in position 2 requires isomerization of secondary ester linkage to primary ester

Question 9

Saponification

Answer 9

• hydrolysis in the presence of heat and strong base (NaOH / KOH)
• NaOH: makes moldable/hard soaps
• KOH: makes liquid/soft soaps
• Product = glycerol (alcohol) + soap (salt of fatty acid)

Question 10

Halogenation

Answer 10

• halogen (bromide = red/orange) is added to C=C in oil

- Product: vicinal dihalide (colorless)

Question 11

Hypertriglyceridemia

Answer 11

• elevated triglycerides in plasma (serum triglyceride level)
• increases risk of heart disease and stroke
• TG lvl can be increased by: certain medications (corticosteroids, beta-blockers, estrogen, and birth control pills) or alcohol consumption

Question 12

Lower Triglyceride level by:

Answer 12

• eating fewer calories
• decreasing carbohydrate consumption (Mono/disaccharides)
• substitute MUFA for Saturated F.A,
• increase physical activity
• decrease alcohol consumption
• drugs: nicotinic acids, fibrates