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Final Flashcards

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1
Q

T or F. Glycosidic bond is more susceptible to acid hydrolysis that peptide bond.

A

True

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2
Q

T or F. Specific heat of water is lower than specific heat of oil.

A

False

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3
Q

T or F. If two polysaccharides, one linear and one highly branched, have the same molecular weight and make solutions of the same concentration, solution of the linear polysaccharide will be more viscous.

A

True

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4
Q

Oxidation of monosaccharides results in the formation of:

A

Polyhydroxy alcohols

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5
Q

High amylose starch contains:

A

50% - 70% amylose

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6
Q

Diameter of starch granules is

A

2-100 micrometer

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7
Q

In waxy starches, amylose content is:

A

less than or equal to 2%

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8
Q

What is a reducing power of maltopentose compared to reducing power of glucose?

A

1/5 (20%)

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9
Q

The largest starch granules are from:

A

potato

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10
Q

Consider two corn syrups with DE of 25 and 85. The corn syrup that has a thicker texture (more viscous) and less sweetness is one with:

A

DE ~25

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11
Q

The Fehling’s test is used to determine:

A

reducing sugars

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12
Q

Gelatinization is:

A

the irreversible swelling of starch granules under to influence of heat in an aqueous medium to give a starch paste.

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13
Q

The last enzyme used in production of HFCS is:

A

isomerase

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14
Q

Beta-amylase hydrolyses amylopectin at:

A

a(1-4) bonds, two glucose unites from non-reducing end

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15
Q

Stability of native starches depends on pH. Which line in the figure below represents viscosity profile of a paste at pH2?

A

d

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16
Q

Maltodextrins have a DE of:

A

5-25

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17
Q

In the figure below, which line presents viscosity development of moderately cross-linked starch?

A

b

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18
Q

T or F. Naturally occurring unsaturated fatty acids have double bond(s) in cis configuration.

A

True

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19
Q

T or F. Palmitic acid (16:0) is a fatty acid found in food triglycerides.

A

True

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20
Q

T or F. Modified starches can be used as fat replacers in salad dressings.

A

True

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21
Q

Fatty acids in food triglycerides are:

A

with even number of carbon atoms

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22
Q

Triglycerides are made of:

A

1 glycerol and 3 fatty acids

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23
Q

Phospholipids are make of:

A

1 glycerol, 2 fatty acids, 1 phosphate and 1 amino acid

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24
Q

Which fatty acid (FA) of those listed below is the most susceptible to autoxidation?

a. Saturated FA at sn-2 in a triglyceride
b. Saturated FA at sn-2 in a phospholipid
c. Saturated free FA
d. Polyunsaturated Free FA

A

d. Polyunsaturated Free FA

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25
Q

Phospholipids are:

A

have both hydrophobic and hydrophilic parts

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26
Q

Oelstra is:

A

non-digestible fat replacer

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27
Q

If a fatty acid has 18 carbons and the first double bond occurs at w3, at which carbon (from omega side) will the second double bond occur?

A

6

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28
Q

In which step of autoxidation reactions of lipids metal ions have a significant role?

A

initiation

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29
Q

The most stable fat crystals are:

A

Beta

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30
Q

“o/w” stands for:

A

oil disperse phase in an emulsion and water is continues phase.

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31
Q

Which of the fatty acids (FA) listed below is the least susceptible to autoxidation?

a. Saturated FA in at sn-2 in a triglyceride
b. Unsaturated FA in a phospholipid
c. Saturated free FA
d. Unsaturated free FA
e. Unsaturated FA at sn-3 in a triglyceride

A

a. Saturated FA in at sn-2 in a triglyceride

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32
Q

Which of the following fatty acids will have the highest melting point?

a. Caprylic (8:0)
b. Stearic (18:0)
c. Oleic (18:1c9)
d. Linoleic (18:2c6)
e. Linolenic (18:3c3)

A

b. Stearic (18:0)

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33
Q

Beta-galctosidase hydrolyses:

A

Lactose

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34
Q

Enzyme that serves as an indicator for efficiency of blanching:

A

Peroxidase

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35
Q

Chymosin (renin) is used for:

A

milk clotting and formation of curds

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36
Q

Formation of bitter taste in cheeses can result from activity of:

A

protease

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37
Q

a-amylase hydrolyses a-1-4 glycosidic bond in amylose and amylopectin:

A

randomly splits a-1-4 glycosidic bonds

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38
Q

Pectin methylesterase is more active on:

A

HMP

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39
Q

Proteolytic enzyme (protease) found in papaya is:

A

Papain

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40
Q

The figure represents reaction rate of an enzyme as a function of:

A

pH

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41
Q

Preheating of potato slices at ~60 degrees Celcius (prior to frying) activates an enzyme after which activity the chips stay firmer during and after frying. This enzyme is:

A

pectin methylesterase

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42
Q

Enzyme that converts glucose to fructose and is used in production of HFCS is:

A

isomerase

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43
Q

Cleaving the glycosidic bonds between methylated galacturonic acids happens at pH>5 or due to enzymatic reaction. The enzyme responsible for this reaction is:

A

pectin lyase

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44
Q

Two enzymes used for removal of glucose from a food product and oxygen fro a headspace are:

A

glucose oxidase and catalase

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45
Q

Enzyme that has Fe as co-enzyme is:

A

Peroxidase

46
Q

Polygalacturonase is commonly used as a processing aid in production of:

A

fruits and vegetable juices

47
Q

Polyphenol oxidases cause discoloration/browning of food by acting on:

A

phenolic compounds

48
Q

For preparation of gels with fresh pineapple, which gelling hydrocolloid should be avoided?

A

Gelatin

49
Q

What is the enzyme that catalyzes this reaction?

H2O2 + AH2 = 2H2O + A

A

POD

50
Q

Peeled potatoes (and apples) are commonly submerged in cold water (that can be sometimes acidified) while waiting for the next processing step. This is done to:

A

Exclude molecular oxygen and reduce rate of reactions catalyzed by PPO.

51
Q

Xanthophylls are:

A

Carotenoids containing oxygen

52
Q

Anthocyanin is:

A

sugar + anthocyanidin

53
Q

Betalains are:

A

Red pigments

54
Q

Solubility of chlorophylls is dictated by the presence of:

A

Phytol side chain

55
Q

Addition of small amounts of baking soda (increase pH) to water for cooking of green vegetables will result in:

A

Bright green color

56
Q

Oxygenation of myoglobin results in formation of:

A

Oxymyoglobin

57
Q

Chlorophyllase is a plant enzyme that:

A

Removes phytol from chlorophyll

58
Q

Oxidation of myoglobin happens when:

A

Iron (II) in a myoglobin losses one electron and becomes iron (III)

59
Q

Magnesium ion can be easily removed from chlorophyll molecule by:

A

Acids

60
Q

Processing step that affects carotenoids the most (causing bleaching) is:

A

Dehydration (drying with heated air)

61
Q

Lycopene is good:

A

antioxidant

62
Q

Potential disadvantage of high concentration of ascorbic acid in food products is in possibility to:

A

Act as a proxidant and/or cause browning

63
Q

Vitamin C is:

A

L-ascorbic acid

64
Q

Vitamin B that contains sulfur and easily degrades at pH >7 is:

A

Thiamin

65
Q

Vitamins that have antioxidant activity are:

A

A,C,E

66
Q

Beta-galactosidase hydrolyses:

A

Lactose

67
Q

In waxy starch, amylose content is approximately:

A

less than or equal to 2%

68
Q

Sweetness that has to be lace led with the statement “phenyketonurics: contain phenylalanine”:

A

aspartame

69
Q

Most commonly used inorganic acid in the food industry is:

A

H3PO4

70
Q

Parabens are most efficient as antimicrobials at:

A

pH does not affect their antimicrobial efficiency

71
Q

Baking powder is:

A

Baking soda + dry acid

72
Q

Benzoic acid has pKa of 4.2. This means that benzoic acid has effective ant microbial properties:

A

at pH

73
Q

A common acidulate that had antimicrobial properties (at levels used in foods) is:

A

Acetic Acid

74
Q

Baking soda is:

A

NaHCO3

75
Q

Sucralose is:

A

Non-caloric sweetener

76
Q

Cation in carbonate or bicarbonate salts that decompose at elevated temperatures and do not require acid for their activity as leaveners is:

A

(NH4)+

77
Q

A common acidulate that also acts as a chelating agent is:

A

Citric acid

78
Q

Chemical leavaners are used in concentration:

A

1%-2%

79
Q

Aspartame is:

A

L-aspartyl-L-phenylalanine methyl ester

80
Q

Salts used to inhibit formation of C. Botulinum toxin, gas formation in Gouda cheese, and/or to produce characteristic color and flavor of some meat products are:

A

Nitrates and Nitrites

81
Q

Mons commonly used acid in the food industry is:

A

Citric acid

82
Q

Chemical leavens are added to food in order to produce:

A

CO2

83
Q

The first increase in toughness during cooking of meat (~40 - 50 degrees C) happens due to:

A

denaturation of actomyosin

84
Q

Vitamin that contains sulfur and easily degrades at pH >7 is:

A

Thiamin

85
Q

T or F. Compounds that have provitamin A activity are good antioxidants.

A

True

86
Q

Lecithin is:

A

Phospholipid naturally occurring in egg yolk

87
Q

Casein micelles stay dispersed in milk due to:

A

highly hydrophilic and charged part of kappa-casein

88
Q

Myosin molecules are held together in thick filaments due to:

A

ionic interactions

89
Q

Collagen (gelatin) gels forming junctions zones caused by:

A

Hydrogen bonds

90
Q

Gels containing raw pineapple should not be prepared with gelatin because of:

A

Bromelain activity

91
Q

To be ‘detected’ as a fragrance or smell, a compound must be:

A

Volatile

92
Q

Protein content in milk is:

A

3-5%

93
Q

T or F. a-tocopheryl acetate is an excellent antioxidant used to prevent autoxidation in lipid-containing foods.

A

False

94
Q

EDTA stands for:

A

Ethylene diamino tetraacetic acid

95
Q

MAG stands for:

A

Monosodium glutamate

96
Q

IMP is used as:

A

Flavor enhancer

97
Q

GMP stands for:

A

Guanosine mono phosphate

98
Q

Maltol is used as a flavor enhancer in:

A

ice creams and candies

99
Q

Tartaric acid is predominant acid in:

A

Grapes

100
Q

Thermoresistant enzyme used as an indicator of proper blanching is:

A

Peroxidase

101
Q

Potential disadvantage of high concentration of ascorbic acid in food products is in possibility to:

A

act as a pro oxidant and/or cause browning

102
Q

T or F. Gluten is soluble in water.

A

False

103
Q

Maltodextrin have a DE of:

A

5-25

104
Q

T or F. Addition of ammonia compounds is allowed in production of certain caramels.

A

True

105
Q

Which sugar/sweetner provides a cooling effect during dissolving?

A

come polyols

106
Q

Trigylcerides are made of:

A

1 glycerol and 3 fatty acids

107
Q

High amylose starch suntans:

A

50-70% amylose

108
Q

Required substrate(s) for caramelization reactions is:

A

only carbohydrates

109
Q

Hysteresis of sorption isotherms is common in:

A

tissue products

110
Q

If solutions were prepared in water with the same concentration of sugars and amino acids and were heated 2 hrs at 100 degrees celcius, which one will have the most of the Maillard reaction products:

A

glucose, lysine, pH9

111
Q

The major reaction during dough formation is:

A

Sulfhydryl-disulfide interchange (intra-intermolecular) in gliadins and glutelins

112
Q

How much volume of water increases during (slow) freezing is?

A

9%

Food Chemistry (5 decks)

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