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Food Chemistry 2 > Food flavors - Salt, bitter, umami + extra > Flashcards

Food flavors - Salt, bitter, umami + extra Flashcards

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1
Q
  • salty taste due to what? (3 ex)
  • salty taste depends on what? –> how?
A
  • salt ions! (Na+, K+, Cl-)
  • depends on size of ions –> smaller sized ions are salty vs larger sized ions tend to be bitter
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2
Q

are these salt: sweet, salty, sour, bitter, umami?
- Pb acetate and Be acetate
- MgSO4
- monosodium glutamate
- KCl and LiCl
- K-bitartrate
- KI and CsCl
- LiBr

A
  • Pb acetate and Be acetate: sweet
  • MgSO4: bitter
  • monosodium glutamate: umami
  • KCl and LiCl: salty
  • K-bitartrate: sour
  • KI and CsCl: bitter
  • LiBr: salty
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3
Q

salts have been used for centuries for 3 functions

A
  1. impart salty taste –> impart flavor to foods
  2. preserve foodstuff –> curtail microbial growth and proliferation
  3. salts can stimulate digestion and enhance appetite –> digestive stimulant!
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4
Q

what is the max threshold for salt concentration?

A

2-2.5% salt (as NaCl) –> above this concentration, NaCl may render the resulting product indigestible or nauseating

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5
Q

use of salt (NaCl) has become a major health issue with general public
- link with what? how?

A
  • with hypertension/high blood pressure
  • Na+ = intracellular ion in body required to achieve chemical/electrical balance –> increase [Na+] in cell –> osmosis: cell will absorb water –> water exerts pressure on cell wall = increase blood pressure
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6
Q

4 approaches to reduce NaCl levels
- without doing what?

A
  • without compromising salty taste
    1. addition of spices: dry mustard, marjoram, onion, garlic, sage, paprika, mushroom, curry, bay leaves, lemon juice
    2. mineral-based salt substitutes (salts of K+ and NH4+ ions)
    3. vegetized salt substitutes: salt(NaCl) + powdered dehydrated vegetables (onion, garlic, celery) as base
    4. Na compounds may also be replaced with compounds of other cations in food products (ie: replace baking powder (NaHCO3) in baking by KHCO3)
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7
Q
  • bitter taste in foods is due to various _______ and ________ compounds
  • bitter taste is ________ –> but in ___________ with other taste sensations, it contributes significantly to consumer ________ of various products + we have come to accept taste with some products
  • examples of foods that tend to be bitter
A
  • organic and inorganic compounds
  • unpleasant –> but in combination… consumer acceptance
  • kale, bitter melon, broccoli, eggplant, coffee, tea, some cheeses
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8
Q

bitter compounds are mostly of _______ origins
- 3 classes of organic compounds responsible for bitterness in foods are ?

A
  • plant
  • alkaloids, glycosides, certain amino acids/peptides
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9
Q

ALKALOIDS:
- _________ compounds widely distributed in plants as _______ with 2 types of acids
- 3 examples

A
  • nitrogenous –> as salts with acetic acid or carboxylic acid
  • quinine, caffeine, theobromine
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10
Q

QUININE:
- what color?
- ______ powder
- soluble in water?
- very bitter?
- used in what?
- used to treat what?

A
  • white
  • amorphous/shapeless powder
  • limited solubility in water although sulfate and hydrochloride salts are H2O soluble
  • one of the most bitter substances known
  • in beverages
  • used to treat malaria
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11
Q

CAFFEINE:
- __________ _______ derivative found in (3)
- solubility in water is 1:50 OR 1:2 depending on what? –> solubility increases with what?
- powerful ________ with GRAS status
THEOBROMINE
- related to ____A___ and found together with it in (2)
- difference to ___A______

A
  • crystalline purine derivative found in coffee beans (1.5%), tea leaves (5%) and cola nuts (2.5%)
  • depends on temperature! increase temp = increase solubility
  • powerful stimulant!
    THEOBROMINE:
  • related to coffee and often found together in various plants (cocoa beans and cola nuts)
  • lacks 1 methyl group attached to N in purine ring
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12
Q

GLYCOSIDES:
- are _______ esterified with various ________
- 4 examples
- what has to be there to elicit bitter taste?

A
  • aglycones esterified with various sugars
  • naringin, hesperidin, coniferin, sinigrin
  • sugar has to be there! if only aglycone –> bland taste
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13
Q
  • these are types of what?
    NARINGIN:
  • found in (2)
  • bitter?
  • hydrolysis yields (2)

HESPERIDIN:
- found in (2)
- hydrolysis yields (2) –> what confers bitter taste?

A
  • types of glycosides! –> bitter taste!
    NARINGIN:
  • found predominantly in grapefruit and bitter orange
  • one of most bitter substances known
  • D-rhamnoglycose and aglycone naringenin (if only naringenin = bland)
    HESPERIDIN:
  • sweet orange and several other citrus fruit
  • rutinose + aglycone hesperetin –> needs rutinose to taste bitter
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14
Q
  • these are types of what?
    CONIFERIN:
  • in what (1)?
  • produces 2 on hydrolysis –> which may be subsequently be oxidized to ________
    SINIGRIN:
  • found in what?
  • yields what? on hydrolysis
A
  • types of glycosides! –> bitter taste
    CONIFERIN:
  • in conifer wood
  • produces glucose and coniferyl alcohol –> vanilin
    SINIGRIN:
  • black mustard seed
  • yields glucose + allyl isothiocyanate
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15
Q

PEPTIDES/AMINO ACIDS –> can yield ______ taste
- hydrophilic or hydrophobic aa will impart this taste?
- examples of aa (3)
HE SHOULD SEND A SLIDE WITH MORE INFO!

A
  • bitter!
  • hydrophobic!
  • proline, isoleucine, valine
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16
Q

UMAMI TASTE:
- describe using 7 words
- perceived in mouth from eating foods such as (3)
- taste due to interactions btw what and what?

A
  • meaty, savory, brothy, pleasant, delicious, appetizing and salivating
  • muscle foods, mushrooms, fermented products
  • due to interactions of umami eliciting substances like glutamates (MSG), nucleotides (IMP, GMP) and their mixtures with specialized receptors in taste buds
17
Q
  • what is MSG formed from?
  • does MSG impart umami taste? how can it do it?
A
  • L-glutamic acid + sodium –> will hydrolyze in food products into glutamic acid
  • NO! salt by itself will not give off particular taste! –> salt added to food product will help enhance flavors + bring out umami flavors
18
Q

how can nucleotides impart umami taste?

A

specialized receptors in taste buds bind nucleotides –> sends signal to release saliva –> saliva contains digestive enzymes that will hydrolyze proteins –> aa impart umami flavor

19
Q

how can fermentation impart umami taste?

A

fermentation (+ enzymatic and chemical modification) can break down compounds/proteins = umami taste
- ie broth, kimchi, soy sauce

20
Q
  • umami eliciting ingredients co-exist in ______ _____ materials –> they act ____________ to enhance sensation in all kinds of foods including (2)
  • due to its increasing demand for food applications, it is produced on a ___________ scale using (3)
A
  • agricultural raw materials –> act synergistically –> including ready-to-eat foods + convenient packaged foods
  • commercial scale using fermentation, enzymatic hydrolysis and acid hydrolysis methods
21
Q

Taste sensitivity
- 2 criteria?
- need to reach what

A
  • solubility and concentration
  • need to reach threshold values –> minimal amount for taste buds to taste
22
Q

some compounds can alter taste elicited by other compounds
- ie: gymnenic acid –> does what?
- miracle fruit does what?

A
  • gymnenic acid makes taste buds insensitive to sweet and bitter
  • miracle fruit makes bitter and sour compounds taste sweet
23
Q

what are the effects of colds or flu and inherited defects on taste inhibition/modification?
- ageusia vs hypogeusia vs dysgeusia

A

GENETICS DEFECTS:
- genetic defects can cause variations in genes that interact with receptors in tongue to elicit particular taste sensations
- Ageusia: variation in phenylthiocarbonate (PTC) gene –> makes taste buds insensitive to taste sensations
- hypogeusia: variations in genes elicit diminished capacity to perceive sensations
- Dysgeusia: gene variations may induce certain permanent unpleasant sensations in mouth such as metallic, rancid, salty taste

24
Q

GEQ!! why do foods not taste the same when we have a cold?

A

NEED TO GOOGLE ANSWER!

25
Q

How can there be food interactions?
- subthreshold levels of ______ reduce sourness in foods
- subthreshold levels of ______ ENHANCES saltiness in foods
- subthreshold levels of ______ reduce saltiness in foods

A

foods = complex systems –> many many compounds coexist with each other –> can produce synergistic effects
- SALT reduces SOURNESS
- ACIDS enhance SALTINESS
- SUGARS reduces SALTINESS

26
Q

3 compounds can improve/intensify flavor quality in foods (increase sensation of taste of certain food products

A
  1. monosodium glutamate: brings out umami flavors of veg and other foods
  2. nucleotides (IMP and GMP): increase sweetness of muscle foods
  3. maltol (3-hydroxyl-2-methyl-4-pyrone): nutty flavor –> enhances flavors of baked goods
27
Q
  • mouthfeel of foods sensed by (2)
  • 3 different sensations + give examples
A
  • sensed by teeth and jaw
    1. pain: burning sensations in tongue –> ginger, hot chili peppers, wasabi
    2. temperature: hot or cold
    3. tactile sensations (sensed by both touching and sensations in mouth) –> texture, astringency and consistency
28
Q
  • pain in mouth desirable?
  • pain caused by which compounds (2)
A
  • slight pain can be pleasant VS too much = undesirable
  • capsaicin and gingerbain –> bind to pain sensing receptors in mouth
29
Q

why does melted ice cream taste sweeter than frozen?
- why do hot foods taste more intensely?

A
  • frozen foods numb your taste receptors –> sensations are less well perceived
  • hot foods dissolve faster –> more kinetic energy = interact more effectively with receptors –> sensations feel more intensely
30
Q

GEQ: why can milk relieve pain sensations from capsaicin and not water?

A
  • because capsaicin is fat soluble and will dissolve in fats contained in milk –> lowers concentration of capsaicin
  • MOSTLY because casein proteins will act as a detergent and bind to capsaicin to make it more soluble –> caseins can also degrade capsaicin
31
Q

GEQ: what are some differences in pain sensations due to hot chili peppers vs hot coffee?

A

GOOGLE ANSWER!

32
Q

examples of how to describe:
- texture
- consistency
- astringency

A
  • texture: hard, soft, brittle, crunchy, grainy
  • consistency: smooth, lumpy, curdled, thick, thin
  • astringency: dry sensations in cheeks/mouth due to precipitation of proteins in saliva in mouth
33
Q

sensory evaluation used to verify what?
- 2 methods? + definition
- who can participate?

A
  • verify consumer’s preferences/acceptance of food products
    1. PREFERENCE testing: useful for new product development –> checks if consumers like it or not compared to existing products on market
  • anyone can participate!
    2. DIFFERENCE testing: useful to assessing differences in sensory quality of foods
  • requires panel trained to be able to discern particular taste sensations and to discriminate levels of intensities to achieve useful results
34
Q

3 methods commonly used for preference testing? + describe

A
  1. SIMPLE PAIRED COMPARISON TEST:
    - A vs B compared for a particular attribute for which they like (ie A is saltier than B)
  2. HEDONIC SCALE:
    - describe taste material with various epithets
    - most commonly used is 9 point scale from dislike extremely (1) to neither like or dislike (5) to like extremely (9) OR reversed
  3. RANKING TEST:
    - 2 or more test samples ranked against each other in terms of particular attribute (ie A is 1st and B is 2nd)
35
Q

6 common methods for difference testing + explain

A
  1. SIMPLE PAIRED COMPARISON TESTING:
    - A vs B
  2. SCHEFFÉ PAIRED COMPARISON TEST: like #1 but quantify how much preference is (ie I prefer A 50% more than B)
  3. MULTIPLE COMPARISON TEST: 3 or more samples –> compare A & B, B & C, A & C
  4. TRIANGLE TEST: 3 samples: 2 identical + 1 different –> choose odd one out
  5. DUO-TRIO TEST: 3 samples: 1 = reference, pick the odd one out of the 2 others
  6. RANKING TEST: rank in order of intensity 2 or more samples for particular attribute (ie color, sweetness)
36
Q

GEQ: which of triangle test or duo-trio test would achieve more reliable results? why?

A
  • triangle test is harder bc duo-trio test gives you a reference (?)
  • GOOGLE!
37
Q

odor/smell = component of ________
- (#) of distinct odors due to what? (2)
- give examples

A
  • component of flavor!
  • 7 distinct odors –> due to shape and sizes of particular molecules
    1. ehereal
    2. camphoraceous
    3. musky
    4. floral
    5. minty
    6. pungent
    7. putrid
    *check slide for more details but prof said to not focus

Food Chemistry 2 (7 decks)

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