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Food Chemistry - FDSC251 > U1 > Flashcards

U1 Flashcards

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1
Q

4 things that characterize lipids

A
  1. solubility in non-polar organic solvents, not water
  2. hydrophobic
  3. fatty mouthfeel and aroma
  4. lubricant properties when isolated
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2
Q

classifications of lipids

A

simple lipids, compound lipids, derived lipids

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3
Q

simple lipid definition

A

esters of fatty acids connected to an alcohol (triglycerides are a glycerol molecule esterified to 3 fatty acids)

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4
Q

major lipid we consume

A

triglycerides - make up >90% of extractable lipids in biological systems

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5
Q

classifications of simple lipids

A

fats and waxes

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6
Q

fat v oil

A

fat - solid at room temp

oil - liquid at room temp

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7
Q

difference between edible fat and pure triglyceride

A

edible consists of a mixture of many different types of triglycerides (many differences on fatty acid length and saturation), so they melt of a wider range than pure triglycerides

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8
Q

wax definition

A

fatty acids esterified with an alcohol rather than a glycerol

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9
Q

examples of waxes

A 
jojoba oil (linear monounsaturated fatty acids with fatty alcohols - liquid at room temp)
bees wax (solid at room temp)
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10
Q

applications for waxes in food

A

sealing agent = cheese
polishing agent = apples
low calorie fat substitute (can’t be digested)

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11
Q

when is a wax biologically active

A

when the fatty acids are esterified to a complex alcohol - cholesterol or vitamin A or retinol. includes a ring structure

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12
Q

compound lipid definition

A

made of simple lipids conjugated to a non-lipid molecule

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13
Q

kinds of compound lipids

A

phospholipid
glycolipid/sphingolipids
lipoproteins

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14
Q

phospholipid structure

A

glycerol, 2 fatty acids, phosphate group, head group

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15
Q

characteristics of phospholipids

A

amphipathic
emulsifiers
complex mixture of different head groups

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16
Q

commercial emulsifier

A

soybean oil

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17
Q

lecithin

A

phosphatidyl choline

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18
Q

phosphatidic acid

A

hydroxyl group

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19
Q

cephalin

A

phosphatidyl ethanolamine

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20
Q

phosphatidyl inositol

A

phosphate group esterified with an inositol 6 carbon ring

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21
Q

phosphatidyl serine

A

phosphate group esterified with the hydroxyl group of serine AA

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22
Q

phsophatidyl glycerol

A

glycerol head group

found in chloroplasts

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23
Q

cardiolipin

A

diphosphatidyl glycerol

beef heart and green plants

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24
Q

plasmalogen

A

CH2-CH2-N+H3

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25
Q

sphingolipids/glycolipids

A

glycerol-like backbone, fatty acids, carbohydrate and/or nitrogenous group
NO GLYCEROL

26
Q

where are sphingolipids and glycolipids

A

associated with membrane lipids - plants and animals

27
Q

sphingolipid structure

A

sphingosine, fatty acid, head group

28
Q

ceramide

A

sphingolipid with head group -H

29
Q

sphingomyelin

A

sphingolipid with head group phosphocholine

30
Q

glycolipid structure

A

carbohydrate esterified to a lipid

31
Q

glycero-glycolipid structure

A

carbohydrate esterified to a glycerol - fatty acids

32
Q

sphingo-glycolipids

A

carbohydrate esterified to a glycerol - fatty acid and nitrogenous group

33
Q

lipoproteins

A

protein-lipid complex; unknown structure

34
Q

HDL

A

high density lipoprotein - protective mechanism that carries cholesterol out of the blood to the liver

35
Q

LDL

A

low density lipoprotein - transports vital substances, but excess leads to accumulation in blood vessels

36
Q

derived lipids

A

derived from simple or compound lipid categories; still retain hydrophobic character

37
Q

categories of derived lipids

A
  1. fatty acids
  2. alcohols and sterols
  3. hydrocarbons and oxygenated derivatives
38
Q

fatty acids

A

chains of aliphatic hydrocarbons with a carboxyl group at one end

39
Q

short fatty acids contribute to

A

flavor when released by lipolysis

40
Q

long fatty acids contribute to

A

soapy flavors when with mineral salts

41
Q

why are free fatty acids bad in frying oils

A

lower smoke point

42
Q

alcohols and sterols defining feature

A

> C6 fatty alcohols - have a hydroxyl group. 4 ring strucutre + hydroxyl makes it amphipathic

43
Q

short alcohols and sterol

A

flavor

44
Q

long alcohols and sterols

A

biologically active

ex. cholesterol

45
Q

examples of other hydrocarbons/oxygenated derivatives

A
  1. aliphatic hydrocarbons
  2. carotenoids
  3. xanthophylls
  4. terpenes
46
Q

what kind of hydrocarbon/oxygenated derivative is of highest interest for food chemists and why

A

terpenes. since they’re build from isoprene units they are componenets of fragrant oils

47
Q

fundamental isoprene unit

A

5 carbons

48
Q

what are the components of essential oils

A

monoterpenes (2 isoprene units - 10C) and sesqueterpenes (3 isoprene units - 15C)

49
Q

nutritive value of triglycerides

A

9kcal/g
37kJ/g
source of essential fatty acids and vitamins

50
Q

lipid function in food

A
  1. mouthfeel - creamy/oily
  2. solubitizes taste and aroma constituents of food
  3. acheive a desired texture, aroma, and mouthfeel
  4. emulsifiers - phospholipids
51
Q

True or False: Lipids are classified by their hydrophobicity, insolubility in water and solubility in non-polar organic solvents?

A

True

52
Q

Fats are made of

a. any alcohol esterified to a fatty acid
b. an alcohol with a single hydroxyl group esterified to a fatty acid
c. glycerol esterified to fatty acids

A

c

53
Q

A substance that stabilizes an emulsion by increasing its kinetic stability is …

a. Emulgent
b. Emulsifier
c. Surfactant
d. All
e. none

A

B

54
Q

Phospholipids are soluble in water and lipids because…
A. Small molecular weight
B. Hydrophobic and hydrophilic
C. High refractive index

A

B

55
Q

Derived lipids are important to food science because…

a. Bioactive properties
b. Nutritional value
c. Functional properties
d. All
e. none

A

D

56
Q

A diglyceride linked to a phosphate and a nitrogenous base is…

a. Sphingolipid
b. Phospholipid
c. Glycolipid

A

b

57
Q

In lecithin, the hydrophilic nitrogenous base is

a. Ethanolamine
b. Serine
c. choline

A

c

58
Q

True or false?

Ceramide is a phospholipid.

A

False - sphinolipid

59
Q

Carotenoids are important because of their…

a. Nutritional value as precursors of vitamin A
b. Technological properties as natural food colorant
c. None
d. Both A and B

A

d

60
Q

True or False?

HDL contains more cholesterol than LDL.

A

false - cholesterol/lipids are low density, so high density lipoproteins contain relatively more proteins

Food Chemistry - FDSC251 (10 decks)

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