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food chem 2 > Food Flavors > Flashcards

Food Flavors Flashcards

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1
Q

what are the 3 components of food flavor?

A
  • taste
  • odor/smell
  • mouthfeel
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2
Q

how is flavor perceived?

A

signals are relayed to the brain from the nose, taste receptors, and mechanical receptors of teeth/jaw/tongue

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3
Q

what are the tastes sensed by taste buds?

A
  • sweet
  • sour
  • salt
  • bitter
  • umami
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4
Q

what causes umami taste?

A

detection of the carboxylate anion of glutamate in specialized receptor cells

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5
Q

what’s responsible for sweet taste?

A

electronegative elements (O & N)

  • alcohols
  • aldehydes
  • certain amino acids (D-histidine)
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6
Q

why is fructose sweeter than glucose sweeter than mannose?

A

the average length of the hydrogen bonds between the sugar and the surrounding water is the key to sweetness. shorter hydrogen bonds = sweeter

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7
Q

why is sucrose sweeter than lactose?

A

the differentiating characteristic between sucrose and lactose is that sucrose contains fructose while lactose contains galactose.
fructose is the sweetest of the monosaccharides relevant, while glucose and galactose are about the same. The cumulative effect of these linked monosaccharides leads to the fact that sucrose is sweeter. sweetness of the monosaccharides is determined by the length of H bonds between sugar and water. the shorter the bond the sweeter the sugar.

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8
Q

which amino acids sweet and which amino acids are bitter?

A

D amino acids (bland-sweet)

L amino acids (bland-bitter)

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9
Q

name some traditional sweeteners

A
  • sugar (sucrose)
  • invert sugar (sucrose split into glu and fru by heat and acid or invertase)
  • conventional corn syrup
  • high fructose corn syrup
  • maltodextrin
  • honey
  • maple sugar
  • molasses
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10
Q

why is honey dark?

what’s the approximate sugar composition of it?

A

polyphenolic compounds

a third fructose, a third glucose, 15-20 water, significant content of phenolics

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11
Q

what sugars does maple contain?

A

glucose, fructose, and sucrose

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12
Q

what’s molasses?

A

dark syrupy liquid left after recovery of sugar from either sugar can or sugar beet

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13
Q

what are some approved alternate sweeteners?

A
  • polyols: xylitol, mannitol, sorbitol, maltitol, lactitol
  • polydextrose
  • fruit juices
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14
Q

what is cariogenicity?

A

formation of plaques and cavities in the mouth. plaque = slimy film formed on teeth that contains a lot of bacteria. when you ingest sugar, bacteria ferment it to make lactic acid which wears down tooth enamel.

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15
Q

what are some criteria for alternate sweeteners?

A
  • cariogenicity
  • sweetness equivalent
  • solubility & viscosity
  • hygroscopicity
  • heat of solution
  • laxative effect
  • cost
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16
Q

what kind of sweetener is generally good for avoiding cariogenicity

A

polyols

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17
Q

sweetness equivalent is concerned with what 2 aspects

A
  • sweetness

- quality of sweetness (absence of bitter after taste)

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18
Q

what’s the significance of the solubility of a sweetener? what happens with a sugar with low solubility?

A

solubility influences mouthfeel, texture and onset of sweetness perception
low solubility leads to a chalky mouthfeel

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19
Q

significance of a sweetener’s viscosity?

A

less viscous sugars (like xylitol) can yield poor bodying effect, whereas higher viscous sugars (like polydextrose) can impart more structure

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20
Q

significance of a sweetener’s hygroscopicity?

which polyols have low hygroscopicity?

A
  • determines shelf stability
  • high hygroscopic materials have shorter shelf lives

mannitol and isomalt are non-hygroscopic

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21
Q

what is heat of solution?

A

heat absorbed or released when one mole of the substance is dissolved in water

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22
Q

cooling effect of sweetener is caused by (endo/exothermic) heat of solution

A

endothermic (aka positive heat of solution).

sweeteners absorb heat, cooling the solution

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23
Q

what is the significance of a sweetener’s cooling effects. name some items where it’s applied

A

provides a “taste edge” over other sugars, especially for mint flavored items

chewing gum, mints, lozenges, coatings, fondants, hard candies, certain chocolates

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24
Q

name sweeteners that impart a cooling effect

A
  • xylitol has most
  • mannitol and sorbitol significant
  • isomalt marginal
  • sucrose and maltitol are very limited
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25
Q

what causes the laxative effect of some sugars?

A

some alt sweeteners are not readily digested, especially the large ones like polydextrose. they can irritate the bowels, so you have to regulate the amount consumed according to guidelines.

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26
Q

what alt sweeteners have a laxative effect

A

polyols, polydextrose

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27
Q

foods containing > ___ g of sorbitol per day or >___ g of mannitol per day or >___ g polydextrose must put a label warning about the laxative effect

A

> 50 g sorbitol
20 g mannitol
15 g polydextrose

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28
Q

true or false: cost is important enough to consider when picking choosing alternative sweeterners

A

yes, dummy. alternative sweeteners tend to be more $$$ so you gotta strike a balance

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29
Q

rank the following sweeteners in ascending sweetness: sorbitol, xylitol, maltitol, isomalt, polydextrose, mannitol

A

polydextrose, isomalt, sorbitol, mannitol, maltitol, xylitol

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30
Q

true or false: you’re allowed to mix alternative sweeteners

A

uh huh. chewing gum often uses a 3:2 ratio of xylitol to sorbitol

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31
Q

properties of xylitol:

A
  • sweetest of the polyols
  • isosweet to sugar
  • no discernable aftertaste
  • metabolized independently of insulin (good for diabetics)
  • resistant to fermentation by oral bacteria
  • high thermal stability
  • high microbiological stability
  • inhibits many food spoilage microorganisms
  • does not react with AAs
  • moderate hygroscopicity
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32
Q

list some applications of xylitol

A
  • chewing gum/other confectionary
  • pharmaceuticals (syrups, chewable tablets)
  • oral hygiene products (toothpaste, mouthwash)
  • diabetic foods
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33
Q

what’s a high intensity sweetener?

A

compounds with many times the sweetness of sucrose, common table sugar

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34
Q

HITs are categorized as Natural and Synthetic. list examples for each

A

Natural: AAs, Miraculin, Thaumatin, Stevia, monellin, brazellin, neoculin, mabinlin

Synthetic: aspartame, acesulfame K, sucralose, alitame, saccharine, cyclamates

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35
Q

which D isomers of amino acids are sweet? which one isn’t?

A

sweet:

  • His
  • Leu
  • Try (35x sweeter)
  • Tyr
  • Gly

not: D-ala

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36
Q

sources of natural HIT?

A
  • miraculin: west african berries “miracle fruit”
  • thaumatin: katemfe fruit
  • stevia leaf
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37
Q

sweetness of thaumatin?

A

2500x

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38
Q

describe aspartame

A
  • methyl ester of the dipeptide, L-astpartyl-L-phenylalanine
  • 200x sweet
  • not heat stable
  • unpleasant aftertaste
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39
Q

describe acesulfame K

A
  • k-salt of methyl-oxathiazine-dioxide
  • 200x sweeter
  • heat resistant
  • no bitter aftertaste
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40
Q

describe sucralose

A
  • trichloro derivative of glucose-fructose
  • contains Cl so some people say you need to be careful with it
  • 600x sweeter
  • more stable than sugar
  • appears many uses
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41
Q

describe alitame

A
  • deriative of L-a-aspartyl-alaninamide
  • 2000-3000x sweeter than sucrose
  • heat stable
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42
Q

describe saccharine

A

Na or Ca salts

200-400x

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43
Q

describe cyclamates

A
  • Na or Ca salts
  • 30-40x sweeter than sucrose
  • converted to cyclohexylamine (carcinogen) intestinal bacteria
44
Q

what causes sour taste?

A

H+ ions from acids, nature of acidic group, buffering capacity, presence of other compounds

45
Q

true or false: H+ ions determine both the degree of sourness and total acidity

A

false, yes degree of sourness, not total acidity

46
Q

list organic acids

A

acetic, adipic, citric, fumaric, lactic, tartaric, malic, propionic, benzoic, sorbic, succinic, succinic anhydride

47
Q

list inorganic acids

A

phosphoric (H3PO4) and HCl

48
Q

reasons for using acidulants?

A
  • flavor enhancement
  • curtail of microbial activity
  • curtail of spoiling enzymes
  • enhance natural antioxidants
  • monitoring pH of fermented foods
  • structural stability (esp pectin jellies and foams)
49
Q

where would you employ:

  • lactic acid
  • citric/ascorbic acid
  • acetic acid
  • tartaric/malic acid
A 
lactic = dairy
citric/ascorbic = fruit juices
acetic = salad dressings
tartaric/malic = desserts
50
Q

where is phosphoric acid used?

A

soft drinks and preservation of meats (in the form of phosphate), to increase water holding capacity

51
Q

where is carbonic acid used?

A

carbonated beverages

52
Q

describe acetic acid

A
  • clear/colorless
  • produced commercially by oxidation of acetaldehyde or butane
  • used as vinegar, which has many uses (preservation of pickles, sauces, relishes, imparting sharp flavor to foods)
  • can be produced by fermentation of fruit juices, sucrose, glucose, malt
53
Q

describe adipic acid

A
  • odorless, white crystalline powder
  • produced by oxidation of cyclohexanol
  • limited solubility in H2O; very soluble in alcohol and acetone
  • classified as GRAS as buffering and neutralizing agent
54
Q

describe citric acid

A
  • most widely distributed in F&V
  • produced from pineapple waste
  • highly soluble in H2O and alcohol
  • classified as GRAS as an acidulant
55
Q

describe fumaric acid

A
  • odorless, white granular or crystalline powder
  • produced by ferm of glucose or molasses by rhizopus species
  • sparingly soluble in H2O and etOH
  • widely used in dry powdered foods where solubility isn’t a quality factor but antioxidant/preservative properties are
56
Q

describe lactic acid

A
  • viscous, colorless to pale yellow, non-volatile liquid with distinct odor
  • produced by ferm of sucrose, potato starch, molasses
  • commonly used as acidulant in dairy
57
Q

describe malic acid

A
  • odorless, white crystalline powder
  • soluble in H2O and etOH
  • commercially produced racemically as D and L isomers
  • used in non-alcoholic beverages, canned tomatoes, fruit products, and pie fillings
58
Q

describe propionic acid

A
  • oily liquid with a slight pungent/rancid odor
  • resembles butyric acid
  • completely miscible with H2O and etOH
  • used in baking to suppress mold growth
59
Q

describe sorbic acid

A
  • almost odorless, white crystalline substance, slight acidic taste
  • limited solubility in H2O and etOH.
  • K, Na, and Ca salts are soluble in H2O and release free acid in low pH media
  • salt forms used for antifungal preservative properties
60
Q

describe succininic acid

A
  • odorless, white crystalline solid
  • sharp acidic and slight bitter taste
  • soluble in both H2O and EtOH
  • GRAS acidulant
61
Q

describe succinic anhydride

A
  • white crystalline powder. stable when dry; converted to succinic acid when dissolved in H2O
  • only anhydride permitted for commercial use
  • used as leavening agent in baked goods
62
Q

describe tartaric acid

A
  • colorless, translucent crystalline powder
  • odorless, strong acidic taste
  • very soluble in H2O and etOH
  • occurs in many fruits, esp grapes
  • obtained as K or Ca salt during wine fermentation
  • GRAS acidulant
63
Q

describe phosphoric acid

A
  • colorless, crystalline solid, but commonly used as clear, syrupy liquid with conc ranging from 75-85%
  • has flat taste. blends well with non-fruit flavors
  • used in formulating cola drinks, cheesemaking, and brewing for pH control
64
Q

what is salt?

A

product of neutralization reactions

65
Q

smaller ions taste (more/less) salty

bigger ions taste (more/less salty)

A

more (similar to NaCl)

less - instead bitter

66
Q

what causes salty taste?

A

presence of salt ions (Na+, K+, Cl-)

67
Q

why don’t we use large salt ions as a sweetener?

A

they’re toxic

68
Q

what are functions of NaCl

A
  • digestive stimulant by promoting appetite

- flavor enhancer

69
Q

what concentration can most people tolerate for salt?

A

up to 2%

70
Q

how is salt related to health concerns?

A

there is perceived link of Na ions with hypertension or high blood pressure in certain individuals

71
Q

how does too much salt cause hypertension?

A

causes water to leave cells and enter blood vessels

72
Q

name some ways to lower salt intake?

A
  • other small cations (K+, NH4+); examples include potassium carbonate. K replaces up to 95% of taste
  • spices to impart flavors
  • vegetized salts: mixing of dry powdered vegetables. total intake of salt is halved
73
Q

give examples of where bitter taste is associated with a food product

A

coffee, cocoa, many veggies, gin

74
Q

what causes bitterness?

A

organic and inorganic compounds of plant origin

75
Q

what are the 3 groups used to classify bitter compounds?

A
  • alkaloids
  • glycosides
  • amino acids/peptides
76
Q

what are alkaloids? what are some examples?

A

N-containing compounds widely distributed in plants as salts with acetic acid or a carboxylic acid

quinine, caffeine, theobromine

77
Q

describe quinine

A
  • white, amorphous powder
  • limited solubility with H2O; can become more soluble with heat; sulfate and hydrochloride salts are water soluble
  • one of the most bitter substances known
  • used in beverages
  • used to combat malaria
  • found in Neem tree in africa
78
Q

describe caffeine

A
  • crystalline purine derivative
  • found in coffee bean, tea leaves and cola nuts
  • solubility in H2O is 1:50
  • powerful stimulant
  • GRAS
79
Q

describe theobromine

A
  • structurally related with caffeine; has one less methyl group than caffeine
  • found together with caffeine in cocoa beans and cola nuts.
  • stimulant, but not as potent as caffeine
80
Q

what are glycosides? name some examples

A

aglycones esterified with various sugars

naringin, hesperidin, coniferin, sinigrin

81
Q

describe naringin

A
  • found primarily in grapefruit and bitter orange
  • hydrolysis yields D-rhamnoglucoside and aglycone - naringenin
  • only bitter with sugar
  • can be hydrolyzed with dilute HCl or naringinase
82
Q

true or false: naringenin is the primary sugar for naringin

A

false: naringenin is the aglycone form (lacking sugar) of naringin

rather, naringin’s sugar is D-rhamnoglucose.

83
Q

describe hesperidin

A
  • aglycone = hesperitin
  • sugar is rutinose
  • ## found in citrus fruits
84
Q

describe coniferin

A
  • in conifer wood
  • aglycone = coniferyl alcohol
  • sugar = glucose
  • alcohol can be oxidized to form vanillin, which has a pleasant smell
85
Q

describe sinigrin

A
  • black mustard seed
  • aglycone = isothiocyanate
  • sugar = glucose
  • isothiocyanate is responsible for particular tingling associated with horseradish and wasabi.
86
Q

explain some scenarios of taste inhibition/modification

A
  • some compounds alter taste of others (ex: gymnemic acid makes taste buds insensitive to sweet and bitter)
  • miracle fruit makes bitter/sour stuff taste sweet
  • being sick can have an effect
  • L-amino acids, being bitter, can affect bitterness of protein if present at terminals.
  • genetics plays a role (25% of population can’t taste isothiocyanate)
87
Q

what are the criteria for taste sensitivity?

A
  • solubility and concentration (threshold values)
88
Q

sub-threshold levels of salt reduces _____ in foods

A

sourness

89
Q

sub-threshold levels of acids enhances _____ in foods

A

saltiness

90
Q

sub-threshold levels of sugars reduces _____ in foods

A

saltiness

91
Q

what are flavor enhancers. examples?

A

compounds that improve or intensify flavor quality in foods

ex) MSG, nucleotides (IMP and GMP), maltol

92
Q

what are the 3 components of mouthfeel

A
  • pain
  • temperature
  • tactile sensations
93
Q

tactile sensations include:

A

texture, astringency, and consistency

94
Q

how can food cause pain?

A
  • physically: presence of sharp objects (including your teeth)
  • chemically: capsaicin and isothiocyanate (spicy)
  • temperature: hot coffee’s hot
95
Q

what’s the significance of a food’s temperature?

A
  • different temps produce different mouthfeels

- ex) warm vs cool coffee or frozen vs melted ice cream

96
Q

is frozen or melted ice cream sweeter?

A

warm is sweeter: warmth induces conformational change, increases interaction with taste receptors

97
Q

what are examples of texture:

A

hard, soft, crunchy, brittle

98
Q

what are examples of consistency

A

thick, thin, smooth, lumpy, curdled

99
Q

what methods of sensory evaluation are there for foods?

A
  • preference testing

- difference testing

100
Q

what is preference testing

A
  • you have different food materials and you find which you prefer. good for verifying consumer acceptance
101
Q

preference testing includes what types of tests?

A
  • simple paired: pair of food products are presented and panel picks which they prefer
  • hedonic: (usually) a 9 point system to describe degree of like/dislike
  • ranking: food product is ranked in terms of various attributes/preferences
102
Q

what methods are available for difference testing?

A
  • simple paired comparison
  • scheffe paired comparison
  • multiple comparison test
  • triangle test
  • duo-trio test
  • ranking test
103
Q

what’s the scheffe paired comparison

A

in addition to saying which component is different, the degree of difference is quantified

104
Q

what’s the multiple paired comparison test?

A

3 or more products are compared with each other for particular attributes

105
Q

what’s the triangle test?

A

presented with 3 items: 2 are the same and panelist must select the odd one

106
Q

what’s the duo trio test?

A

presented with 3 coded items. one of the 3 are used as a reference. the task is either to select the other identical or different.

107
Q

what are the 7 primary odors?

A
  • ethereal
  • camphoraceous
  • musky
  • floral
  • minty
  • pungent
  • putrid

food chem 2 (5 decks)

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