Food Flavors Flashcards
1
Q
what are the 3 components of food flavor?
A
- taste
- odor/smell
- mouthfeel
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
3
Q
what are the tastes sensed by taste buds?
A
- sweet
- sour
- salt
- bitter
- umami
4
Q
what causes umami taste?
A
detection of the carboxylate anion of glutamate in specialized receptor cells
5
Q
what’s responsible for sweet taste?
A
electronegative elements (O & N)
- alcohols
- aldehydes
- certain amino acids (D-histidine)
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
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.
8
Q
which amino acids sweet and which amino acids are bitter?
A
D amino acids (bland-sweet)
L amino acids (bland-bitter)
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
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
11
Q
what sugars does maple contain?
A
glucose, fructose, and sucrose
12
Q
what’s molasses?
A
dark syrupy liquid left after recovery of sugar from either sugar can or sugar beet
13
Q
what are some approved alternate sweeteners?
A
- polyols: xylitol, mannitol, sorbitol, maltitol, lactitol
- polydextrose
- fruit juices
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.
15
Q
what are some criteria for alternate sweeteners?
A
- cariogenicity
- sweetness equivalent
- solubility & viscosity
- hygroscopicity
- heat of solution
- laxative effect
- cost
16
Q
what kind of sweetener is generally good for avoiding cariogenicity
A
polyols
17
Q
sweetness equivalent is concerned with what 2 aspects
A
- sweetness
- quality of sweetness (absence of bitter after taste)
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
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
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
21
Q
what is heat of solution?
A
heat absorbed or released when one mole of the substance is dissolved in water
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
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
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
25
what causes the laxative effect of some sugars?
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.
26
what alt sweeteners have a laxative effect
polyols, polydextrose
27
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
>50 g sorbitol
>20 g mannitol
>15 g polydextrose
28
true or false: cost is important enough to consider when picking choosing alternative sweeterners
yes, dummy. alternative sweeteners tend to be more $$$ so you gotta strike a balance
29
rank the following sweeteners in ascending sweetness: sorbitol, xylitol, maltitol, isomalt, polydextrose, mannitol
polydextrose, isomalt, sorbitol, mannitol, maltitol, xylitol
30
true or false: you're allowed to mix alternative sweeteners
uh huh. chewing gum often uses a 3:2 ratio of xylitol to sorbitol
31
properties of xylitol:
- 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
32
list some applications of xylitol
- chewing gum/other confectionary
- pharmaceuticals (syrups, chewable tablets)
- oral hygiene products (toothpaste, mouthwash)
- diabetic foods
33
what's a high intensity sweetener?
compounds with many times the sweetness of sucrose, common table sugar
34
HITs are categorized as Natural and Synthetic. list examples for each
Natural: AAs, Miraculin, Thaumatin, Stevia, monellin, brazellin, neoculin, mabinlin
Synthetic: aspartame, acesulfame K, sucralose, alitame, saccharine, cyclamates
35
which D isomers of amino acids are sweet? which one isn't?
sweet:
- His
- Leu
- Try (35x sweeter)
- Tyr
- Gly
not: D-ala
36
sources of natural HIT?
- miraculin: west african berries "miracle fruit"
- thaumatin: katemfe fruit
- stevia leaf
37
sweetness of thaumatin?
2500x
38
describe aspartame
- methyl ester of the dipeptide, L-astpartyl-L-phenylalanine
- 200x sweet
- not heat stable
- unpleasant aftertaste
39
describe acesulfame K
- k-salt of methyl-oxathiazine-dioxide
- 200x sweeter
- heat resistant
- no bitter aftertaste
40
describe sucralose
- 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
41
describe alitame
- deriative of L-a-aspartyl-alaninamide
- 2000-3000x sweeter than sucrose
- heat stable
42
describe saccharine
Na or Ca salts
| 200-400x
43
describe cyclamates
- Na or Ca salts
- 30-40x sweeter than sucrose
- converted to cyclohexylamine (carcinogen) intestinal bacteria
44
what causes sour taste?
H+ ions from acids, nature of acidic group, buffering capacity, presence of other compounds
45
true or false: H+ ions determine both the degree of sourness and total acidity
false, yes degree of sourness, not total acidity
46
list organic acids
acetic, adipic, citric, fumaric, lactic, tartaric, malic, propionic, benzoic, sorbic, succinic, succinic anhydride
47
list inorganic acids
phosphoric (H3PO4) and HCl
48
reasons for using acidulants?
- 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
where would you employ:
- lactic acid
- citric/ascorbic acid
- acetic acid
- tartaric/malic acid
```
lactic = dairy
citric/ascorbic = fruit juices
acetic = salad dressings
tartaric/malic = desserts
```
50
where is phosphoric acid used?
soft drinks and preservation of meats (in the form of phosphate), to increase water holding capacity
51
where is carbonic acid used?
carbonated beverages
52
describe acetic acid
- 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
describe adipic acid
- 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
describe citric acid
- most widely distributed in F&V
- produced from pineapple waste
- highly soluble in H2O and alcohol
- classified as GRAS as an acidulant
55
describe fumaric acid
- 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
describe lactic acid
- 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
describe malic acid
- 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
describe propionic acid
- 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
describe sorbic acid
- 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
describe succininic acid
- odorless, white crystalline solid
- sharp acidic and slight bitter taste
- soluble in both H2O and EtOH
- GRAS acidulant
61
describe succinic anhydride
- 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
describe tartaric acid
- 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
describe phosphoric acid
- 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
what is salt?
product of neutralization reactions
65
smaller ions taste (more/less) salty
bigger ions taste (more/less salty)
more (similar to NaCl)
less - instead bitter
66
what causes salty taste?
presence of salt ions (Na+, K+, Cl-)
67
why don't we use large salt ions as a sweetener?
they're toxic
68
what are functions of NaCl
- digestive stimulant by promoting appetite
| - flavor enhancer
69
what concentration can most people tolerate for salt?
up to 2%
70
how is salt related to health concerns?
there is perceived link of Na ions with hypertension or high blood pressure in certain individuals
71
how does too much salt cause hypertension?
causes water to leave cells and enter blood vessels
72
name some ways to lower salt intake?
- 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
give examples of where bitter taste is associated with a food product
coffee, cocoa, many veggies, gin
74
what causes bitterness?
organic and inorganic compounds of plant origin
75
what are the 3 groups used to classify bitter compounds?
- alkaloids
- glycosides
- amino acids/peptides
76
what are alkaloids? what are some examples?
N-containing compounds widely distributed in plants as salts with acetic acid or a carboxylic acid
quinine, caffeine, theobromine
77
describe quinine
- 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
describe caffeine
- crystalline purine derivative
- found in coffee bean, tea leaves and cola nuts
- solubility in H2O is 1:50
- powerful stimulant
- GRAS
79
describe theobromine
- 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
what are glycosides? name some examples
aglycones esterified with various sugars
naringin, hesperidin, coniferin, sinigrin
81
describe naringin
- 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
true or false: naringenin is the primary sugar for naringin
false: naringenin is the aglycone form (lacking sugar) of naringin
rather, naringin's sugar is D-rhamnoglucose.
83
describe hesperidin
- aglycone = hesperitin
- sugar is rutinose
- found in citrus fruits
-
84
describe coniferin
- in conifer wood
- aglycone = coniferyl alcohol
- sugar = glucose
- alcohol can be oxidized to form vanillin, which has a pleasant smell
85
describe sinigrin
- black mustard seed
- aglycone = isothiocyanate
- sugar = glucose
- isothiocyanate is responsible for particular tingling associated with horseradish and wasabi.
86
explain some scenarios of taste inhibition/modification
- 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
what are the criteria for taste sensitivity?
- solubility and concentration (threshold values)
88
sub-threshold levels of salt reduces _____ in foods
sourness
89
sub-threshold levels of acids enhances _____ in foods
saltiness
90
sub-threshold levels of sugars reduces _____ in foods
saltiness
91
what are flavor enhancers. examples?
compounds that improve or intensify flavor quality in foods
ex) MSG, nucleotides (IMP and GMP), maltol
92
what are the 3 components of mouthfeel
- pain
- temperature
- tactile sensations
93
tactile sensations include:
texture, astringency, and consistency
94
how can food cause pain?
- physically: presence of sharp objects (including your teeth)
- chemically: capsaicin and isothiocyanate (spicy)
- temperature: hot coffee's hot
95
what's the significance of a food's temperature?
- different temps produce different mouthfeels
| - ex) warm vs cool coffee or frozen vs melted ice cream
96
is frozen or melted ice cream sweeter?
warm is sweeter: warmth induces conformational change, increases interaction with taste receptors
97
what are examples of texture:
hard, soft, crunchy, brittle
98
what are examples of consistency
thick, thin, smooth, lumpy, curdled
99
what methods of sensory evaluation are there for foods?
- preference testing
| - difference testing
100
what is preference testing
- you have different food materials and you find which you prefer. good for verifying consumer acceptance
101
preference testing includes what types of tests?
- 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
what methods are available for difference testing?
- simple paired comparison
- scheffe paired comparison
- multiple comparison test
- triangle test
- duo-trio test
- ranking test
103
what's the scheffe paired comparison
in addition to saying which component is different, the degree of difference is quantified
104
what's the multiple paired comparison test?
3 or more products are compared with each other for particular attributes
105
what's the triangle test?
presented with 3 items: 2 are the same and panelist must select the odd one
106
what's the duo trio test?
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
what are the 7 primary odors?
- ethereal
- camphoraceous
- musky
- floral
- minty
- pungent
- putrid
