Lipids Part 1

Question 1

Biological significance of fats

Answer 1

Act as fuel in the body Caloric value 9kcals/gm
Fats underneath skin exerts insulating effects
Padding and protecting internal organs
Building materials. Cholesterol-hormone synthesis

Question 2

Lipids

Answer 2

Consists of fixed oils,fats,waxes
Esters of long chains fatty acids and alcohols or of closely related derivatives

Question 3

Examples of fixed oils fats and waxes

Answer 3

Fixed oils -peanut oil, castor oil
Fats- animals lard
Waxes- beeswax

Question 4

Primary function of lipids

Answer 4

Energy storage/source of energy

Question 5

Boiling point of fixed oils and Fats

Answer 5

Lower bp fixed oil
Higher bp fat

Question 6

Physical properties of cocoa butter

Answer 6

Solid from plant

Question 7

Physical properties of cod liver oil

Answer 7

Liquid from fish

Question 8

Physical properties of fixed oil and saturated fats

Answer 8

Fixed oil roomtemp liquid from plant
Saturated solid

Question 9

Saturated fatty acids

Answer 9

Butyric
Caproic
Caprylic
Capric

Question 10

PUFA
polyunsaturated fatty acid

Answer 10

Two or more double bonds
Members of omega 3 and omega 6 fa essential fatty acids

Question 11

Essential fatty acids

Answer 11

Linolenic acid omega 3 FA
Linoleic acid omega 6 FA

Question 12

Richest source of PUFA

Answer 12

Vegetable oils
Corn sunflower cotton seed oils

Question 13

EFA- omega 3 and 6 FAs

Answer 13

Omega indicates first double bond from the methyl group
First point of unsaturated if next to the third carbon (omega 3 fa)
Great significance on human nutrition and health issues

Question 14

Importance of lipids

Answer 14

Energy storage
Signaling molecule
Structural component of cell membrane

Question 15

Properties of lipids

Answer 15

Physical- fixed oil
Greasy
Lighter than water
Insoluble in water
Soluble in organic solvents

Question 16

Properties of lipids
Chemical

Answer 16

Hydrolysis-addition of water trigly yield glycerol and fatty acid
Rancidity- intial products aldehydes and ketones
Final products oxidation: acid RCOOH
Acrolein test- prescence of glycerol/ formation of propenal

Question 17

Enzyme in hydrolysis

Answer 17

Lipase (catalyze)

Question 18

Rancidity

Answer 18

Sesame walnut factor
Exposure light/air
Oxidation
Unpleasant odor/flavor
Byproduct of lipids smelly breath

Question 19

Acrolein test

Answer 19

Dehydrating agent fat
Potassium bisulfate KHSO4
To form unsaturated aldehyde
Pungent irritating odor
Has triglycerol

Question 20

Acid value or acid number

Answer 20

The number of mg of KOH required to neutralize the free fatty acids in 1g of substance

Question 21

Saponification value

Answer 21

Number of miligarams of KOH to neutralize the free fatty acids and saponify the esters contained in 1 g of the substance.

Question 22

Iodine number

Answer 22

Number of grams of iodine absorbed under prescribed conditions by 100 grams of substance indicates the degree of unsat

Question 23

Methods of obtaining fixed oils of vegetables and animal origin

Answer 23

Fixed oil fats of vegetable origin are obtained by expression in hydraulic presses
Virgin oil or a cold pressed oil if the expression is carried out in cold
Hot expression if the expression is carried out in heat
2. Sometimes organic solvents are used for extraction oils

Question 24

What are the classes of lipids based on its ability to absorb oxygen from air

Answer 24

Drying oils
Semidrying oils
Nondrying oils

Question 25

Drying oils

Answer 25

Linseed oil/cod liver oil- paint industry
When exposed to air undergoes oxidation turn to tapefilm
Iodine # above 120

Question 26

Semidrying oils

Answer 26

Sessame/cottonseed
When exposed to air little bit oxidation forming thin film
Iodine #100-120

Question 27

Nondrying oils

Answer 27

Olive oil/almond oil
Never undergoes oxidation no film
Iodine # lower 100