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Food Science exam 1 > Food Science exam 1 > Flashcards

Food Science exam 1 Flashcards

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1
Q

pH that defines low vs high acid

A

4.6

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2
Q

3 types of water

A

Free, absorbed and bound

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3
Q

Associated in layers by hydrogen bonds, typically around hydrophilic molecules

A

Absorbed water (structural)

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4
Q

Chemically bound, water of hydration, water ion

A

Bound water

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5
Q

ratio of vapor pressure of food divided by vapor pressure of pure water at same temp

A

Water activity (Pure water=1)

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6
Q

Water flows from ___ to ___ water activity

A

high to low

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7
Q

How to prevent water migration aka lower water activity?

A

salting, freezing, drying, sugar coat (raisins)

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8
Q

Water activity less than ____ equals a shelf stable food

A

0.6

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9
Q

Microorganisms are most active around ph of __

A

7

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10
Q

Organic acids?

A

Malic, tartic, citric, fumanic, lactic, acetic

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11
Q

Glucose and galactose are aldose or ketose sugars?

A

Aldose (CHO)

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12
Q

Fructose is a aldose or ketose sugar?

A

ketose (C=O)

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13
Q

Disaccharides are joined with a ___ bond

A

glycosidic

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14
Q

Sucrose is made from ___ and ___ with a ___ bond

A

glucose and fructose, alpha 1,2

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15
Q

Lactose is made from ___ and ___ with a ___ bond

A

glucose and galactose, beta 1,4

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16
Q

Maltose is made from ___ and ___ with a ___ bond

A

glucose and glucose, alpha 1,4

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17
Q

____ is the only non reducing sugar

A

Sucrose

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18
Q

Reducing sugars have a free

A

aldehyde or ketone group

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19
Q

The sweetest sugar is

A

fructose

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20
Q

invert sugar is

A

sucrose and h2O converted to glucose and fructose by enzyme invertase, less likely to crystallize than sucrose

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21
Q

Three browning reactions

A

Enzymatic, caramelization, and malliard browning

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22
Q

Caramelization and malliard are enzymatic or non enzymatic?

A

Non

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23
Q

Reaction bt oxygen and phenolic compounds

A

Enzymatic browning (browning in bananas and avocado)

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24
Q

Enzymatic browning can be prevented by:

A 
remove oxygen 
add vitamin C 
heating 
decrease pH 
adding sulfites
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25
Q

The thermal decomposition of carbohydrates

A

Caramelization

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26
Q

The reaction between a reducing sugar and an amino group

A

Malliard browning

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27
Q

Malliard browning can be controlled by

A

control temp
decrease pH
reduce water activity

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28
Q

Homogenous- a solute dissolved in a solvent

A

Solution

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29
Q

Heterogenous and unstable

A

Suspension

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30
Q

Heterogenous and stable, consists of dispersed phase and continuous phase

A

Colloidal dispersion

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31
Q

Starch is composed of

A

amylose and amylopectin

32
Q

Amylose structure

A

linear chain with alpha 1,4 bonds

33
Q

Amylopectin structure

A

branched chain w alpha 1,6 bonds

34
Q

A food higher in ____ (amylose/amylopectin) will absorb more water

A

amylopectin

35
Q

What is corn syrup

A

Starch treated with enzymes to make maltose and glucose mixture

36
Q

What is high fructose corn syrup

A

Glucose isomerase converts glucose to glucose and fructose

37
Q

Cellulose structure

A

Linear with Beta 1,4 bonds, cant digest

38
Q

Types of gums

A

Agar, xantham, pectins, guar, carob/lust, tara

39
Q

If you increase mixing (shear) then particles

A

either line up in the direction of the force or particles clump to a force

40
Q

What is PKU?

A

recessive genetic disorder where people cant convert phenylalanine. (aspartame contains phenylalanine)

41
Q

Flavor that is imparted by glutamate and ribonucleotides

A

Umani

42
Q

MSG is

A

a sodium salt of glutamic acid

43
Q

Protein denaturation is

A

any modification of structure that doesnt break peptide bonds

44
Q

Proteins can be denatured by

A

acid
heat
mechanical force

45
Q

Clumping of denatured proteins which results in thickening or hardening

A

Protein coagulation

46
Q

Protein coagulation is caused by

A 
Heat
enzymes
mechanical
acid 
salt
47
Q

Milk coagulation is caused by

A

Chymosin, lower acidity

48
Q

Dispersed and continuous phases in a sol

A

solid, liquid

49
Q

Dispersed and continuous phases in a gel

A

liquid, solid

50
Q

Dispersed and continuous phases in a emulsion

A

liquid, liquid

51
Q

Dispersed and continuous phases in a solid foam

A

gas, solid

52
Q

Dispersed and continuous phases in a foam

A

gas, liquid

53
Q

What proteins make up gluten and which is responsible for viscosity or elasticity

A

Gliadin-viscosity

Glutenin- elasticity

54
Q

High gluten results in

A

tough and chewy like pizza dough

55
Q

Celiac disease is

A

gluten sensitivity (gliadin antibodies)

56
Q

Less than ____ ppm equals gluten free

A

20

57
Q

What makes you cry when you cut an onion?

A

Compartmentalization- when you cut it releases a lachrymatory agent

58
Q

Added to food to inhibit enzymatic action

A

sulfites

59
Q

Trypsin inhibitors do what

A

prevent protein digestion

60
Q

What enzyme is used in fruit juice processing

A

Pectinase- breaks down cell wall

61
Q

A carboxylic acid with a hydrocarbon chain attached

A

Fatty acid- amphipathic

62
Q

Triglyceride is

A

3 fatty acids bound to glycerol

63
Q

Phospholipid is

A

glycerol with 2 FAs and phosphate group attached

64
Q

Sterols in plants vs animals

A

phytosterols vs cholesterol

65
Q

Fat soluble vitamins are

A

lipids

66
Q

Fats have a melting

A

range bc of mixed composition

67
Q

Melting range of fats is affected by

A

fatty acid composition
FA chain length
degree of saturation
configuration of double bonds

68
Q

What is a conjugated fatty acid

A

FA with 2 or more double bonds separated by a single bond (inhibit carcinogens and promote weight loss)

69
Q

Omega 3 FAs

A

EPA and DHA

70
Q

TAG composition

A

Can detect if fats have been altered based on triglyceride composition

71
Q

Oxidative rancidity is the result of

A

uptake of oxygen and formation of peroxides, hydroperoxides

72
Q

How to control oxidative rancidity

A

Control amount of unsaturated FAs, oxygen conc., limit UV light, control temp, remove sources of metal catalysts, addition of antioxidants

73
Q

What antioxidants can be added to food

A

Vita E, citric acid, BHA, BHT, EDTA, phosphates, rosemary

74
Q

What is hydrolytic rancidity?

A

hydrolysis of triglycerides to free fatty acids and glycerol (often catalyzed by lipases)used for some cheese

75
Q

What kind of molecule is a good emulsifier

A

Amphiphiles (egg yolk in mayo)

76
Q

What is brominated vegetable oil?

A

Used to stabilize citrus and fruit flavored drinks (gatorade, mtn dew), prevents seperation of less dense flavoring agents

Food Science exam 1 (1 decks)

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