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F & F > Topic 3A > Flashcards

Topic 3A Flashcards

1
Q

lipid

A

Soluble in organic solvents (ex: alcohol) but not water

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2
Q

oils

A

lipids liquid at room temp

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3
Q

fats

A

lipids solid at room temp

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4
Q

what are the 3 major groups of fats & oils?

A

o Triglycerides
o Phospholipids
o Sterols
o In addition: waxes

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5
Q

triglycerides

A

• Composed of 3 FAs combined with one molecule of an alcohol called glycerol

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6
Q

FA

A

hydrocarbon chain with carboxyl grp (acidic) at the end

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7
Q

glycerol structure

A

3 C atoms + 3 OH grps

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8
Q

what type of FA is found in fat in food?

A

mixed triglyceride

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9
Q

what type of bond joins 3 FAs to the glycerol in triglycerides? & what type of rxn occurs for this to happen?

A

ester linkage

condensation

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10
Q

how are triglycerides classified?

A

number of C atoms & saturation

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11
Q

FAs have C chains as short as ____ Cs & as long as _____

A

4

24+

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12
Q

short chain FAs

A

up to 12 C atoms

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13
Q

medium chain FAs

A

12 or 13 C atoms

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14
Q

long chain FAs

A

16 C atoms

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15
Q

saturated fats

A

all H-C can bond to & no double bonds b/w C atoms

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16
Q

consumption of what type of fat is linked to heart disease?

A

saturated fat

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17
Q

are saturated fats solid or liquid at room temp? & why?

A

solid

Straight chain enables close packing

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18
Q

what type of food fats are saturated?

A

animal fat, butter, coconut oil, palm oil, milk fat

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19
Q

unsaturated fats

A

contain double bonds b/w C atoms & don’t have all H atoms

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20
Q

are unsaturated fats solid or liquid at room temp? & why?

A

liquid

Double bonds cause bends in the chain, aren’t as compact causing it to be liquid

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21
Q

what is a benefit of unsaturated fats?

A

prevent clotting of blood

good for the heart

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22
Q

what type of food fats are unsaturated?

A

canola oil, soybean oil, fish oil, duck oil

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23
Q

linoleic acid (omega-6)

A

has 18 C atoms, 2 double bonds, found in most foods especially oilseeds such as canola & soybeans

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24
Q

what is the stability of linoleic acid (omega-6)? & what is the effect of its oxidation?

A

Stable at high temperature, but can be oxidized

Once oxidized, not as beneficial

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25
Q

linolenic acid (omega-3)

A

18 C atoms, 3 double bonds, found mostly in soybeans, flaxseeds & hempseeds

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26
Q

what is the stability of linolenic acid (omega-3)?

A

More sensitive to oxidation

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27
Q

what does the number in omega-6 & omega-3 FAs indicate?

A

where first double bond appears

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28
Q

what is the recommendation of omega-3 & omega-6 acquirements in an American diet?

A

increase omega 3 & decrease omega -6

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29
Q

what determines the shape of FAs?

A

presence of double bond, configuration of the bond

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30
Q

cis configuration

A

H atoms all on the same side of the double bond

Repel one another & cause a bend in the chain

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31
Q

what configuration of FAs is natural in nature?

A

cis

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32
Q

trans configuration

A

H atoms are on the opp sides of the double bond

Balanced, less repulsion causing it to be straight & solid

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33
Q

how are trans FAs formed?

A

when heating cis

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34
Q

what physical property does the shape of a FA effect?

A

melting point

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35
Q

trans FAs have ____ melting point than cis FAs

A

higher (cis molecules cannot compact as closely therefore, less E is required)

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36
Q

trans FAs behave similarly to what molecule? & how?

A

saturated FAs

raising cholesterol

37
Q

hydrogenation

A

Forced addition of H atoms to the unsaturated bonds in an unsaturated fat

unsaturated to saturated FA

38
Q

how does hydrogenation effect the melting point of a fat?

A

raises

39
Q

what is the side effect of hydrogenation?

A

trans bond

40
Q

when is hydrogenation used in the food industry?

A

used to harden liquid oils into semi-solid fats

41
Q

hydrogenation makes the oil more resistant to what?

A

oxidative rancidity

42
Q

what is the effect of hydrogenation of linoleic acid?

A

becomes biologically inactive when converted to the trans form

43
Q

why is hydrogenation carried out?

A

make the oil more solid at room temp (ex: margarine & shortening)

increase the stability of these oils to thermal temps

44
Q

shortening

A

medium level hydrogenation, contains 10-20% trans FAs

45
Q

soft tub margarine

A

medium level hydrogenation contains 13-20% trans FAs

46
Q

hard margarine

A

High-level hydrogenation, contains 25-28% trans FAs

47
Q

trans FAs

A

hydrogenation converts cis –> trans

48
Q

which FA is less stable & why?

A

unsaturated FAs –> double bonds are more reactive

when exposed to oxygen it will undergo an oxidative rxn at the point of unsaturation

49
Q

are trans FAs or saturated FAs more harmful?

A

trans FAs

50
Q

why is hydrogenated margarine more harmful than butter?

A

Butter doesn’t have trans-fats, margarine does have trans-fat

Short-chained FAs in butter are good for the bacteria in the large intestine, margarine has long chained FAs

51
Q

how is non-hydrogenated margarin produced?

A

emulsification of water & oil creating a soft solid

52
Q

phospholipid

A

Glycerol molecule with 2 FAs attached & a phosphate molecule

53
Q

how do phospholipids & triglycerides differ?

A

phospholipids have a phosphate & triglycerides don’t

54
Q

longer the FA chain =

A

the more hydrophobic

55
Q

how does a phospholipid act as an emulsifier?

A

Hydrophilic head & 2 hydrophobic tails

Hold water & fat together with the hydrophilic & hydrophobic properties

56
Q

lecithin & ex of where its used

A

phospholipid used in various foods including margarine

emulsifier

mayonnaise

57
Q

what food source is a good source of phospholipids?

A

egg yolk & soybean oil

58
Q

sterol

A

Hydrophobic, complex

Composed of multiple benzene rings held together

59
Q

what type of sterol is found in animal foods?

A

cholesterol

60
Q

what happens if cholesterol levels are too high in the blood?

A

can lead to heart disease & prevent normal flow of blood

61
Q

what is cholesterol a pre-cursor for?

A

vit D

62
Q

what is bile made from?

A

cholesterol

63
Q

pre-cursor

A

something that can be transformed into an active compound

64
Q

what type of nutrient is cholesterol?

A

non essential

65
Q

cholesterol is involved in the production of what 3 substsnces?

A

bile

vit D

some hormones

66
Q

what lipid is used as a protective coating in foods?

A

waxes

67
Q

plasticity & when is it desirable

A

a plastic fat will become deformed when force is applied but keeps its new shape on a flat surface

spreadable products (ex:butter)

68
Q

aeration & when is it used in food?

A

trapping air in the product, solid fats can retain the air

cookies, cakes & other baked goods

69
Q

what role does lipid have in bread?

A

Slows down staling of bread starch, prevents starch from forming crystals

70
Q

how do lipids effect flavouring of food?

A

Fat has the unique ability to absorb & preserve flavors

Often infused with herbs & spices for preservation

Also contain compounds that lend specific flavor of their own

71
Q

how do lipids effect heat transfer?

A

As food contacts hot oil, moisture from the food escapes & oil enters the food
Enables the food to be cooked faster b/c oil can reach a higher temperature than water

Heat also seals the food surface minimizing the entry of oil & escape of moisture
If the temp isn’t high enough, the surface takes longer to seal allowing more oil to penetrate the food
High oil food will absorb more moisture

72
Q

what advantage do lipids serve in smoking point?

A

fats have a higher smoking point than oil

73
Q

what are the functional properties of lipids?

A

plasticity

aeration

texture & flavour

heat transfer

melting point

smoking point

74
Q

how does oxidation effect lipid quality?

A

Unsaturated bonds react with oxygen

Causes oxidative rancidity
Staleness of the oils
Can damage esophagus leading to a burning sensation heart burn
Damages cells

75
Q

how can an oxidation rxn with lipids be prevented?

A

storing used oil in lower temps
store in air tight containers
store in dark containers

76
Q

fractionation & how is it done?

A

separation of HM point & LM point components by controlled cooking (HM –> fats & LM –> oils)

Winterization: placing oil in cold place 
Saturated FAs solidify & unsaturated liquid  FAs will separate
77
Q

why is fractionation done?

A

Consumer oil products (Ex: salad dressings) will become hazy & consumers won’t find it appealing, industries separate the FAs to prevent this

78
Q

what 2 products are obtained by fractionation?

A

Good frying oil

Good plastic fat for making shortening

79
Q

hydrolysis in a triglyceride

A

addition of a water molecule to a triglyceride releasing 3 FAs & a glycerol

80
Q

hydrolytic rancidity & what is it a result of?

A

Glycerol & SFA contributing to the rancid flavors

hydrolysis

81
Q

what is more likely to get rancid –> butter or shortening?

A

BUTTER –> lots of SFA

Happens when: water is available, when the enzyme can access the position to break down the bond & it is easier when FAs are shorter

BUTTER lots of SFA & water in butter (not 100% fat) will become rancid when stored at room temp

Shortening has long chained FAs, no water & is saturated

82
Q

intersterification

A

rearranging the FAs in triglycerides can produce desirable consistency of the product

83
Q

how does the interesterification rxn occur?

A

Hydrolyzes bonds b/w FAs & glycerol molecule –> FAs can reattach to the free glycerol molecule
Diff combinations of FA attachment can occur

84
Q

what is the result of an interesterification rxn?

A

Produce more hydrogenous triglycerides composition (all 3 of the same FAs will attach to one glycerol molecule)

85
Q

polymerization

A

polymer of FAs formed when oil is heated to smoking point

triglycerides start to form polymers, in nature they are separate

86
Q

how does polymerization effect fats & oils?

A

increases the viscosity

87
Q

how is the rate of polymerization determined?

A

how long it was heated

88
Q

what effect does polymerized oil have on human health?

A

toxic towards humans

F & F (8 decks)

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