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College Bowl 2019 > Food Chemistry > Flashcards

Food Chemistry Flashcards

1
Q

What compound in chocolate stimulates the central nervous system and also makes dogs sick?

A

Theobromine

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2
Q

What chemical hormone do fruits release upon ripening?

A

Ethylene

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3
Q

Chlorophyll molecule reacting with hydrogen exhibits what shade of green?

A

Olive Green

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4
Q

What two common compounds are used together as an antioxidative system?

A

Ascorbic Acid and Citric Acid

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5
Q

What is the name of the final degradation compound of chlorophyll?

A

Pheophorbide

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6
Q

What is an isomer that is cheaper than Vitamin C?

A

Erythorbic Acid

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7
Q

What is the enzyme responsible for browning in apples and lettuce?

A

Polyphenol Oxidase

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8
Q

What are the acids present in fish oil?

A

Arachidonic Acid, DHA, and EPA

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9
Q

What is surimi?

A

A concentrate of microfibrillar proteins of fish muscle.

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10
Q

What is Carboxyl-methyl cellulose often used for?

A

Thickener in foods (and stabilizer)

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11
Q

Does Kosmotrope ion discourage water structure?

A

No (they cause water molecules to favorably interact)

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12
Q

What is the main class of color compounds found in raspberries?

A

Anthocyanins

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13
Q

What is the major color compound in tomatoes?

A

Lycopenes

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14
Q

What is the structural difference between chlorophyll and chlorophyllide?

A

Chlorophyllide does not have a phytol tail

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15
Q

What happens to chlorophyll on heating?

A

Pheophytin forms

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16
Q

Alar is the trade name for what chemical compound?

A

Daminozide

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17
Q

How many polypeptide chains make up an antibody?

A

Four

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18
Q

What is the winterization process for an oil?

A

Cooling the oil and filtering of the solids formed so that long chained saturated fats do not crystallize at low temperatures.

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19
Q

What is the structural difference between chlorophyll and pheophytin?

A

Pheophytin does not have magnesium in porphyrin ring.

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20
Q

Peptide bond formation results in the formation of what secondary compound?

A

Water

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21
Q

What metabolic end product does the Voges-Proskauer test detect?

A

Acetoin in a baceterial broth culture

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22
Q

Will lipid oxidation be higher at a water activity of .05 or .5?

A

0.05

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23
Q

How many carbon atoms and how many double bonds are there in arachidonic acid?

A

20 carbons and 4 double bonds

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24
Q

What are the three stages of oxidative rancidity?

A

Initiation, Propagation, and Termination

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25
Q

What ketohexose is most significant to food chemists?

A

Fructose

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26
Q

How many carbon atoms are there in the fatty acid myristic acid?

A

14

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27
Q

What is the Peroxide Value a measure of?

A

Fat Oxidation

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28
Q

Waxes are composed of what two basic chemical entities?

A

Fatty Acid (Ester linked) to Fatty Alcohol

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29
Q

Name three effects of protein denaturation.

A 
Decreased solubility
altered water-binding capacity
loss of biological activity, 
increased susceptibility to attack by proteases
increased intrinsic viscosity, 
inability to crystallize.
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30
Q

Name 3 physical agents capable of denaturing proteins.

A 
Temperature Changes Mechanical Actions 
Change in pH
Irradiation
Sound Waves
Exposure to Mineral Salt and Metals
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31
Q

Name two main gluten proteins.

A

Gliadins and Glutenins

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32
Q

How do sodium chloride and sucrose affect foam stability?

A

Sodium chloride reduces foam stability and sucrose improves foam stability.

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33
Q

Name three factors useful in controlling enzyme activity.

A 
Temperature
Water Content and Activity
Extremes of pH
Chemicals
Alterations of Substrates
Alterations of Products
Preprocessing Controls
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34
Q

Name 3 chemical agents capable of denaturing proteins.

A 
Acids
Alkalis
Metals
Organic Solvents
Aqueous Solutions of Organic Solvents
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35
Q

Name 5 proteins with good foaming properties.

A 
Egg white proteins
the globin part of hemoglobin
bovine serum albumin
gelatin
whey proteins
casein micelles
B-casein
wheat protein
soy proteins
some protein hydrolyzates.
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36
Q

Name 3 reasons it is advantageous to obtain enzymes from microorganisms.

A

Microorganisms are very versatile,
MO’s can be altered by mutations or genetic engineering to produce a greater quantity of enzyme or different enzymes,
recovery of enzymes is often easy,
readily available,
high rate of growth and enzyme production.

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37
Q

What effect would the addition of sodium bicarbonate have to chocolate?

A

Smoother,
less acid and less bitter chocolate flavor,
darker color,
and improved solubility (elevated pH enhances sugar-amino browning reactions and polymerization of flavonoids).

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38
Q

Name 5 chelating agents used in the food industry.

A 
EDTA, 
citric acid, 
malic acid, 
tartaric acid, 
oxalic acid, 
succinic acid, 
adenosine triphosphate, 
pyrophosphate, 
porphyrins, 
and proteins.
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39
Q

Name 2 heat stable enzymes in food that are important to the quality of aseptic products.

A 
Lipase, 
lipoxygenase, 
catalase, 
chlorophylase, 
peroxidase, 
pectinase, 
protease, 
ascorbic acid oxidase, 
alkaline phosphotase.
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40
Q

Chlorophyll molecule reacting with magnesium shows what shade of green

A

Bright green

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41
Q

At low water activity what is the main deteriorative concern?

A

Lipid oxidation

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42
Q

Name one way foam stability can be assessed.

A

The degree of liquid drainage or foam collapse (foam reduction) after a given time,
the time for total or half-drainage (or half-reduction in volume),
or the time before drainage starts.

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43
Q

Name 4 advantages of using enzymes in food processing.

A 
They are natural, nontoxic substances, 
generally catalyze without unwanted side-effects, active under very mild conditions of temperature and pH, 
active at low concentrations,
 rate of reaction can be controlled, 
can be inactivated after reaction.
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44
Q

S-(1-propenyl)-L-cysteine sulfoxide is the chemical precursor to the major flavor compounds in what foodstuff?

A

Onions ( or leeks)

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45
Q

What kinds of food emulsions are? (1) Butter (2) Mayonnaise(3) Milk

A 
Butter= water in oil Mayonnaise= oil in water 
Milk= oil in water
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46
Q

What is the fundamental driving of electrophoresis?

A

The speed of a molecule is proportional to the surrounding voltage gradient.

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47
Q

How can a molecular weight of protein, DNA, and RNA be determined?

A

For proteins: SDA-PAGE.

For DNA & RNA: Agarose gel.

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48
Q

How does HPLC differ from FPLC?

A

HPLC has higher pressure than FPLC

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49
Q

What are two common reducing agents that break disulfide bonds in proteins?

A

2-mercaptoethanol (2-ME),

dithiothreitol (DDT)

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50
Q

In polyacrylamide gel electrophoresis (PAGE) what purpose do ammonium persulfates (APS) and TEMED serve?

A

They act as catalysts, speeding the polymerization of acrylamide.

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51
Q

What does the acronym NPN stand for?

A

Non-protein nitrogen

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52
Q

Name three nonpolar polar, and charged amino acids.

A

Nonpolar: (Valine, Alanine, Leucine, Isoleucine, Proline, Tryptophan)

Polar: (Glycine, Serine, Cystein, Threonine, Tyrosine)

Charged: (Lysine, Arginine, Histidine, Aspartic Acid, Glutamic Acid)

53
Q

What name is given to the small circular DNA molecules that carry genetic information independently of the main bacterial chromosome?

A

Plasmids

54
Q

In genetics what is conjugation?

A

DNA transferred by cell to cell contact (bacterial sex).

55
Q

Which will be coldest at its freezing point: 1M dispersion of amylose 1M solution of NaCl, distilled water, or 1M solution of sucrose?

A

NaCl (it dissociated to a 2M solution)

56
Q

What metabolic disorder prevents conversion of phenulalanine to tyrosine by normal metabolic pathways?

A

Phenylketonuria

57
Q

What does MSG stand for?

A

Monosodium Glutamate

58
Q

What happens to a bottle of wine if before you bottle it you forget to put the stuff in it that prevents it from fermenting?

A

It explodes

59
Q

If you take 20 ml of .1 M NaOH to titrate 40 mL of an HCL solution to the penolphthalein end point what is the molarity of the HCL solution?

A

.05 M HCL

60
Q

What does the “c” stand for in the equation E=mc2?

A

Speed of Light

61
Q

20 grams of amylose is added to 80 grams of water in a beaker; the boiling point is measured with an ordinary mercury-in-glass thermometer. What is the observed boiling point of the material in the beaker?

A

100 Degrees Celsius (it is not a true solution-there is no boiling point of elevation)

62
Q

If oxygen attacks an unsaturated fatty acids at the double bond what is the resultant product?

A

Two aldehydes

63
Q

In the enzyme Taq Polymerase what does Taq stand for?

A

Thermus Aqauticus

64
Q

What are the primary secondary, tertiary, and quaternary structures?

A

Primary-amino acid sequence. Secondary-alpha-helix, beta sheet. Tertiary-one complete protein chain with cross bonds linking it together. Quaternary-four separate protein chains assembled as one.

65
Q

Define molarity, molality, and normality.

A

Molarity is moles of substance per liter solution. Molality is moles of substance per kg solvent. Normality is equivalents of substance per liter solution.

66
Q

How is pH defined?

A

Negative log of the hydrogen concentration (mol/l).

67
Q

What charge will a protein have when the pH of its solution is below, at, and above its pKa?

A

pH below positive charge; pH at no charge; pH above negative charge

68
Q

What does the iodine value measure and how is it measured?

A

pH below positive charge; pH at no charge; pH above negative charge

69
Q

What does the iodine value measure and how is it measured?

A

The amount of unsaturated bonds in fat; grams Iodine reacting with 100 grams fat.

70
Q

What does the saponification value measure and how is it measured?

A

Number of fatty acids present; mg KOH needed to saponify 1 g fat.

71
Q

What does Acid Degree Value measure and how is it measured?

A

Amount of free fatty acids present; mg KOH needed to neutralize the free fatty acids in 1 g of fat.

72
Q

Water A) Is the major component of most foods.B) Controls shelf-life or storage capabilityC) Regulates chemical and microbiological reactionsD) All of the above

A

D) All of the Above

73
Q

Which of the following foods contain the lowest content of water?A) Fresh Carrots B) Fresh Tomatoes C) Whole Milk D) Fresh Celery

A

C) Whole Milk

74
Q

Which of these food additives could be used to prevent cocoa particles from settling in chocolate milk? A) BHA (butylated hydroxyanisole B) Carrageenan C) Thiamine Hydrochloride D) Citric Acid

A

B) Carrageenan

75
Q

Which of the following examples of browning is enzymatic in nature? 1. Browning of sugars as a result of heating 2. Browning of freshly cut surfaces of fruits and vegetables 3. Browning of bread during toasting 4. Browning of potato chips

A

Browning of freshly cut surfaces of fruits and vegetables.

76
Q

What would be a safe processing time for heat processing green beans in a boiling water bath? A. 30 minutes B. 300 minutes C. Depends on the size of the food container D. None of the above

A

D: None of the above

77
Q

Which of these foods is not appropriate to this list? A) Salami B) Yogurt C) Orange Juice D) Beer

A

A: Orange Juice

78
Q

To which of the following four basic tastes are humans most sensitive? A) Bitter B) Sweet C) Sour D) Salty

A

Bitter

79
Q

At what pH is benzoic acid most effective?

A

pH 3-5

80
Q

What is acid proteolysis?

A

Degradation of protein and production of acid from sugar at the same time.

81
Q

What is catalase?

A

An enzyme that converts hydrogen peroxide to water plus oxygen.

82
Q

What reaction does the enzyme “reverse transcriptase” catalyze?

A

RNA transcribed to DNA

83
Q

What pigment was first designated as anthocyanins?

A

Blue pigment in flowers

84
Q

What is the chemical nature of anthocyanins?

A

Glycosides of anthocyanidins

85
Q

Name a naturally occurring protein sweetener.

A

Thaumautin

86
Q

What is the chemical nomenclature for caffeine?

A

1, 3, 7-trimethylxanthine

87
Q

Name three non-nutritive sweeteners approved for use in USA?

A

Acsulfame-K, Saccharin, Succralose, Aspartame

88
Q

Which two amino acids is the aspartame derived from?

A

Aspartic Acid and Phenylalanine

89
Q

Are sorbitol and mannitol sweet?

A

Yes

90
Q

What are the fructose contents in commercial HFCS products.

A

45%, 52%, 90%

91
Q

What are the limiting amino acids in corn, potato, and green peas?

A

Corn- Lysine, Potato-Methionine, Green Peas-Methionine

92
Q

Which amino acid has the greatest molecular weight: tryptophan or tyrosine?

A

Tryptophan

93
Q

Give one word for a carbon atom involved in hemiacetal or acetal formation.

A

Anomeric

94
Q

What degradative enzyme causes browning in apples, pears, bananas, and peaches?

A

Polyphenoloxidase

95
Q

Name the two components that comprise the relaxing factor in muscle fibers.

A

Troponins and Tropomyosin

96
Q

An emulsifier with a high hydrophilic-lipophilic balance (HLB) value would promote which type of emulsion: oil in water or water in oil?

A

Oil in Water

97
Q

What is the protein efficiency ratio (PER) of casein?

A

2.5

98
Q

What two enzymes degrade pectic substances?

A

Pectin methylesterase & polygalacturonase

99
Q

Match the number of carbon atoms with the common name of these saturated fatty acids. Carbon #: 4:0 10:0, 12:0,14:0, 16:0, 18:0Common Name: Myristic, Butyric, Capric, Lauric, Stearic, Palmitic

A

4:0 (Butyric), 10:0 (Capric), 12:0 (Lauric), 14:0 (Myristic),16:0 (Palmitic), 18:0 (Stearic)

100
Q

What is a polymorphism?

A

Solid phases of the same chemical composition that differ by crystalline structure, but yield identical liquid phases upon melting.

101
Q

Name 3 factors influencing the consistency of commercial fats.

A

Proportion of solids in the fat, number, size, and kinds of crystals, viscosity of the liquid, temperature treatment, and mechanical working.

102
Q

What does HLB stand for and what does a high and low HLB value indicate?

A

HLB (hydrophilic-lipophilic balance); a low value (3-6) promotes water in oil emulsions and a high value (8-18) promotes oil in water emulsions.

103
Q

Name 3 factors influencing the rate of lipid oxidation in foods.

A

Fatty acid composition, free fatty acids versus the corresponding glycerols, oxygen concentration, temperature, surface area, moisture, pro-oxidants, antioxidants

104
Q

Name two reasons why fats are hydrogenated.

A

It allows the conversion of liquid oils into semisolid or plastic fats and it improves the oxidative stability of the fat.

105
Q

Name three compounds capable of poisoning the catalyst during commercial hydrogenation.

A

Phospholipids, water, sulfur compounds, soaps, partial glycerol esters, carbon dioxide, and mineral acids.

106
Q

Name the three positively charged amino acids.

A

Lysine, Arginine, and Histidine

107
Q

If the absorption of a sample is being determined spectrophotometrically at 420 nm what color is the sample?

A

Blue/purple

108
Q

What enzyme is most responsible for browning bananas?

A

Polyphenol Oxidase

109
Q

During freezing what are the two stages in the crystallization process?

A

Nucleation or crystal formation and crystal growth.

110
Q

In what food is butyric acid typically found?

A

Milk

111
Q

What is the name given to a mixture of equal parts of Darel Lisomers?

A

Racemic Mixture

112
Q

What enzyme causes hyrolytic rancidity in milk?

A

Lipase

113
Q

Name two enzymes that are involved in softening fruits.

A

Pectin Esterase, Polygalacturonase, Pectin Layase

114
Q

Name the strongest biochemical bond and the weakest biochemical bond.

A

Covalent (strongest) and Hydrophobic (Weakest)

115
Q

What is the enzyme that softens tomatoes?

A

Pectin Esterase

116
Q

Name a commonly used household chemical leavening agent and the gas it generates.

A

Sodium bicarbonate generates CO2

117
Q

Name two non-enzymatic browning reactions.

A

Carmelization and Maillard

118
Q

What are the three main steps in the autooxidation of lipids?

A

Initiation, Propagation, Termination

119
Q

What are the only phenols approved for use in the microbiological preservation of foods?

A

Parabens

120
Q

What is the common name for 9 12, cis-cis-octa dienoic acid?

A

Linoleic Acid

121
Q

What are 3 mesomorphic structures associated with lipids in the liquid state?

A

Lamellar; Hexagonal I, II; Cubic

122
Q

What are proteins which are soluble in 50-80% ethanol known as?

A

Prolamines

123
Q

What are colloids that are stabilized by a layer of solvation called?

A

Emulsoids

124
Q

What are soluble polymers of anhydro-galacturonic acid and its esters called?

A

Pectins

125
Q

What is the geometric configuration of double bonds in most natural fatty acids?

A

Cis

126
Q

The undesirable clarification of orange juice or tomato juice (precipitation of pulp) is caused by what enzymes?

A

Pectin methyl esterase or galacturonase

127
Q

What is the movement of molecules through a semi permeable membrane from a region of low to high solute concentration called?

A

Osmosis

128
Q

What is the name of the structural carbohydrate found in lobsters crab, shellfish, and insects?

A

Chitin

College Bowl 2019 (6 decks)

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