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Food Chemistry > Lipid > Flashcards

Lipid Flashcards

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1
Q

Is lipid hydrophobic or hydrophilic

A

hydrophobic

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2
Q

What are the 3 major classes?

A

simple lipids, compound lipids, derived lipids

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3
Q

What are the two categories of simple lipids?

A

fats ( triglycerides, edible fat/oils) and waxes (fatty alcohol esters and jojoba)

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4
Q

what are the 3 categories of compound lipids?

A

phospholipids (lecithin), glycolipids, lipoproteins

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5
Q

what are the 3 categories of derived lipids?

A

fatty acids, fatty alcohol, hydrocarbons (oxygenated derivatieves and flour/color compounds)

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6
Q

what is the definition of simple lipids?

A

esters of fatty acid connecte to an alcohol. The esters of fatty acid are connected to glycerol

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7
Q

what is the definition of compounds lipids?

A

conjugated to non-lipid moiety

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8
Q

what is the definition of derived lipids?

A

derived from simple/compound classes

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9
Q

what is another synonym of simple fat

A

triacylglycerol

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10
Q

What the term oil refers to?

Indice MP

A

refers to fat that have a low melting point and are liquid at room temperature. Fat is solid at room Temp

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11
Q

The most lipids found are

A

triglycerides

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12
Q

What is the difference between the melting point of a pure triacylglycerol and a typical edible fat

A

The edible fat melts over a much wider range of temperature because it consists of a mixture of many different pure triacylglycerol molecules, each with different melting points

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13
Q

What is an wax? Give some examples

A

esters of fatty acids esterified with an alcohol, other than glycerol.
EX: jojoba oil, bee’s wax

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14
Q

What are the applications of food use for waxes?

A

Largely used as sealing agents (cheese) and polishing agents (apple) Also being considered of potential low-calories food ingredient which give a “fatty sensation”but provides FEW CALORIES.

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15
Q

Apart from food, what other product could wax be used for ?

A

cosmetics

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16
Q

what are some compounds in the wax category?

A

complex alcohols such as cholesterol, esters of vitamin A or retinol

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17
Q

True or false

Waxes are important because they are biologically active

A

true

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18
Q

Compound lipids are made up with what

A

They are made up of a sigle lipid (generally the triglyceride type) conjugated to a non lipid molecule

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19
Q

What are phospholipids made of?

A

Is a triglycerides with one of thei fatty acid replaced with a non lipid moiety - phosphoric acid

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20
Q

Phosphoric acid is conjugated to what?

A

to some other non-lipid molecule

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21
Q

What is the basic structure of the non-lipid moiety

Indice : has a X

A

phosphatidic acid
X=OH
X is nitrogenous base

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22
Q

What is the structure for phosphatic acid

A

X=OH

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23
Q

what is the structure for phosphatidylethanolamine

A

X=O-CH2-CH2-NH2

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24
Q

What is the structure for phosphatilchoine

A

X=O-CH2-CH2-N(CH2)3

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25
Q

what is the structure for phosphatidulserine?

A

X=O-CH2-CH(NH2)-COOH

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26
Q

what is the structure for phosphatylinositol

A

hexagone with OH see slide 15

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27
Q

what are some common classes phospholipids

A
  • lecithins (phosphatidyl choline)
  • cephalins (phosphatidyl ethanolamines)
  • phosphatidyl inositols
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28
Q

What are the % of lipid material found in food systems?

A

less than 5%

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29
Q

Phospholipids are commercially used for what? and give an exemple

A

commercially useful as emulsifiers - common source is soybean oil

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30
Q

Glyco- and sphingolipids are associated with what types of membranes?

A

memebrane lipids in both animals and plants

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31
Q

what are the structure of glycolipids and sphingolipids

A

combination of glycerol-like backbone, F.A, carbohydrate, and/or a nitrogenous group

32
Q

True or false

glyco-sphingolipids have a lot of consequence to food scientist

A

False, they have little to do with food

33
Q

what is the chemical composition of sphingolipids?

A

sphingosine
F.A
R-group

34
Q

what types of glycolipid are found in cells

A

glycolipd and glycoprotein

35
Q

what is the function of lipoprotein

A

they circulate in blood to carry lipids to tissues for metabolism or storage and they storage HDL (more protein) and LDL (more lipid)

36
Q

what is the difference between the HDL and the LDL

A

HDL: high-density lipoprotein. It is considered good cholesterol. 1/3 of all blood-circulating cholesterol. Serve as a protective mechanism from the development of heart disease by carring away cholesterol from vessel walls and plaque to the liver disposal.

LDL: low-desnity lipoprotein. Bad cholesterol. It transports substances vital to cell function and development. When there is a lot it can be harmful - lead to blockages of arteries, plaque build up. Related to heart attach and stroke

37
Q

T OR F

the actual structure of lipoproteins is rarely known

A

true

38
Q

what are derived lipid

A

constituents taht are derived from the simple or compound lipid categories and that still retain their hydrophobic character

39
Q

give the categories of derived lipids

A
  1. fatty acid
  2. fatty alcohol
  3. hydrocarbons and oxygenated derivatived therof
40
Q

where are derived lipids found

A

food system

41
Q

what are the difference between short and long F.A

A

short : flavour compounds, released by lipolysis . Long chain don’t have a flavour per se but in the presence of mineral salts it can give a soapy flavour

42
Q

F.A Give their names
C4
C6
C8

A

C4: butyric acid
C6: caproic acid
C8: caprylic acid

43
Q

true or false

In fatty alcohols short chains give flavours

A

true

44
Q

what are terpernes

A

unsaturated hydrocarbons made of isoprene units

45
Q

Terpenes are known of?

A

as components of the fragant oils obtained from leaves, flowers and fruits

46
Q

what are the main constituents of essential oils

A

monoterpenes (10C, 2 isoprene unit ), sesquiterpenes (15C, 3 isoprene units)

47
Q

what is the fundamental isoprenet unit

A

5 carbons

monoterpenes - 2 isoprene - 10 C

sesquiterpenes - 3 isoprene - 15 C

diterpenes - 4 isoprene - 20C

sesterterpenes- 5 isoprene - 25 C

triterpenes - 6 isoprene - 30 C

48
Q

Lipid content can rise by 15-20% to serve what

A

as a commercial source for isolation of triacylglycerol and be sold as fats or oils

49
Q

What is the nutritive importance of lipids

A 
Fuel molecules (9kcal/g) and a source of fatty acids and vitamins
Pleasant creamy or oily mouthfeel and the ability to solubilize many taste and aroma constituents of food
50
Q

The 2 components (ipids) most interested in food systems are?

A

fats (95-96%) and phospholipds

51
Q

in what form fatty acids are found

A

combined in the form of triglycerides (they assembled to the glycerol)

52
Q

what are the 2 basic types of fatty acids

A
  1. saturated fatty acid (simplest and least reactive)

2. unsaturated fatty acid

53
Q

true or false

fatty acids founds in nature tend to be even numbered

A

true

54
Q

How many carbons there is in a short chain and a long chain of F.A? and what is there state

A

short chain F.A: C4-C12 and they are liquid at room temperature

longer chain F.A: more than C12 and they are solid

55
Q

Who has a lower melting point: short chains or longer chains.

A

short chain has a lower melting point.

56
Q 
Give the melting point of 
butric acid (C4)
lauric acid (C10)
and myristic acid (C12)
A

Butric acid : -7.9
lauric acid : 44
myrictic acid: 54.4

57
Q

Why does water solubility decreases with increasing in chain lenght

A

due to the increasing hydriohobicity

58
Q

Fatty acids that have odd numbers are presented where

A

present in food only in traces

59
Q

Which fatty acids (there is 2) that are found in milk and plants oils

A

pentadenoic (15C)

Heptadenoic (17C)

60
Q

What are the most common unsaturated fatty acids

A

oleic, linoleic and linolenic

61
Q

how many carbons and double bond there is with :
oleic acid
linoleic acid
linolenic acid

A

oleic acid: (18:1)
linoleic acid: (18:2)
linolenic acid : (18:3)

62
Q

what are the 2 major systems to name staurated fatty acids

A

trivial names and systematic names

63
Q

how can you name a an acid with a systematic way

A

the number of carbons (Greek numerical system) + suffix noic

ex:: penta(5C) + noic= pentanoic

64
Q 
what are the common name of :
ethanoic (C2)
butanoic (C4)
hexanoic (C6)
Octanoic (C8)
Decanoic (C10)
dodecanoic (C12)
Tetradecanoic (C14)
Hexadecanoic (C16)
Octadecanoic (C18)
Eicosanoic (C20)
Docosanoic (C22)
A
  • acetic
  • butyric
  • caproic
  • caprylic
  • capric
  • lauric
  • myristic
  • palmitic
  • stearic
  • arachidonic
  • behenic
65
Q

How is the presence of a double bond indicated in nomenclature?

A

enoic

66
Q

how is the name of these molecules:
C18:1
C18:2
C18:3

A

octadecenoic
octadecadienoic
octadecatrienoic

67
Q

How is the name od these molecules given their position
C18:1 (9)
C18:2(9,12)
C18:3(9,12,15)

A

octadeca-9-enoic acid
octadeca-9,12-dienoic acid
octadeca-9,12,15-trienoic acid

68
Q

In the IUPAC system from where is counted the double bond?

A

from the carboxyl end

69
Q

If you have cis and trans configuration how can you write

C18:2(9c,12t)

A

octadeca-cis-9,trans-12-dienoic acid

70
Q

What is the difference in the cis and trans form?

A

cis form: hydrogenes are on the same side of the carbon chain
trans form: the hydrogens are on opposite sides of the carbn chain

71
Q

which conformation (cis or trans) is easier to pack? and which has a higher melting point?

A

trans and trans has also a higher melting point, because it packs more

72
Q

Put in the correct other for melting point?
1= high
3=low

A

1) saturated
2) trans
3) cis

73
Q

what happens regarding cis/trans during hydrogenation?

A

a side reaction in the conversion of the natural cis form to trans

74
Q

what is the main mechanism for oils becoming plastic fats during hydrogenation?

A

cis -> trans

75
Q

What is a positional isomerism?

A

the double bond is located on the fatty acid chain

76
Q

What are the 2 forms of how the double bonds are situated?

A

unconjugated double bond: the double bonds are separed by a methylene group

conjugated double bonds: they are next to each other

Food Chemistry (11 decks)

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