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Food Chemistry 2 > Food flavors - Intro + Sweet and Sour > Flashcards

Food flavors - Intro + Sweet and Sour Flashcards

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1
Q

what does food flavors refer to?

A

sensations produced by food in the mouth and the olfactory epithelium

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2
Q

food flavors are sensed by (3)

A
  • smell signal from nose
  • taste signal from tongue
  • mouthfeel from teeth, jaws, tongue
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3
Q

components in food interact with ___________ –> impulses are then sent to ______ where signals are translated into distinct _________ that we associated with compounds

A
  • interact with receptors
  • sent to CNS
  • into distinct flavors
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4
Q

3 components of food flavor
- which 2 do we focus the most on?

A
  1. taste
  2. mouthfeel
  3. odor / smell
    - focus on taste and mouthfeel
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5
Q

food flavors classified into:
1. _________ flavors –> def + 4 examples
2. ______ flavors –> 2 types
3. ______ flavors –> 3 types

A
  1. natural flavors –> produced by living orgs (plants, animals, microbes)
    - herbs (basil, parsley), spices (cardamon, clove, cinnamon), fruits (orange, lemon), vegetables (peas, onion, garlic)
  2. processed flavors
    a) thermally produced (caramelized, roasted, cooking, frying)
    b) produced by microorganisms (fermented)
  3. added flavors:
    a) natural extracts (almond, cola, apricot)
    b) essential oils (lavender, peppermint)
    c) synthetic flavors (alcohols, esters)
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6
Q

how are synthetic flavors made?

A

by chemical synthesis

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7
Q

why do we have different taste sensation in taste buds?

A

because food molecules have different structural components, different charges and different sizes –> bind to different receptors

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8
Q

what type of molecules cause :
1. sweet taste + which tongue region
2. sour taste
3. salt taste
4. bitter taste
5. umami taste

A
  1. electronegative atoms of organic compounds (O, N, S, Br, I)
    - sensed in taste buds in front regions of tongue
  2. Hydrogen ions from acids
  3. salts –> produced from acid (non metal component) and base (metallic compound)
  4. organic compounds (glycoside?)
  5. salts of aspartate and glutamate
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9
Q

are all salts salty?

A

no! some salts can be sweet or bitter
- the salty taste we know is associated with table salt/NaCl
- ie: MgSulfate –> large –> bitter

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10
Q

what type of isomers are D-histidine and L-histidine? vs Glucose and fructose

A
  • D vs L histidine –> optical isomers bc mirror images
  • glucose and fructose –> structural isomers
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11
Q

why do L and D-histidine impart different sweet sensations? even though same size/MW?

A

GOOGLE ANSWER!

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12
Q

why do glucose and fructose impart different sweet sensations? even though same size/MW/formula

A

GOOGLE ANSWER!

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13
Q

What are examples of molecules that elicit sweet taste? (3)
- what is sucrose?

A
  1. alcohols (glycerol, xylitol)
  2. aldehydes (cinnamic aldehyde)
  3. certain amino acids, proteins, and peptides (ie D-Histidine)
    * sucrose = aldehyde + hydroxyl groups
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14
Q

do sweeteners have a higher or lower relative sweetness compared to sucrose?

A

higher!
- saccharin: 250-550
- aspartame: 120-200
- sucralose: 550-750
- cyclamate: 30-50
- acesulfame K: 200
- alitame: 2000

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15
Q

which natural sugar has higher relative sweetness than sucrose?
- rank: maltose, sucrose, fructose, lactose, galactose, glucose –> low to high

A

fructose!
lactose (0.15-0.3) < galactose (0.32) < maltose (0.5) < glucose (0.6) < sucrose (1) < fructose (1.2-1.8)

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16
Q

how is relative sweetness of sugars calculated?

A

arbitrary scale where sucrose is 1.00

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17
Q

what are the 4 advantages of sweeteners?

A
  1. small amount but really sweet bc sweeter than sucrose
  2. metabolized independantly of insulin –> good for diabetes
  3. less calories –> better for obesity
  4. not fermented by bacteria of mouth to produce acids that can eat away or erode tooth enamel to cause decay and cavities
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18
Q

what are the 3 disadvantages of sweeteners?

A
  1. potential harm to future generations –> some may be carcinogenic
  2. may not taste the same as natural sweeteners (aspartame has aftertaste + can break down when put in hot drink to produce aspartic acid)
  3. cost of producing artificial sweeteners cans be high and add to cost of products
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19
Q

how are cavities formed? what is the word for it?

A

bacteria eat natural sugars and ferment them –> produce acid that eats enamel
- cariogenicity

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20
Q

which amino acids taste umami/sour, sweet and bitter?

A

UMAMI/SOUR:
- glutamate
- aspartate
SWEET: –> PASTAGG
- proline
- asparagine
- serine
- threonine
- alanine
- glutamine
- glycine
BITTER:
- tryptophan, phenylalanine, tyrosine
- methionine, cysteine
- histidine, arginine, lysine
- leucine, isoleucine, valine

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21
Q

which aa form (D or L) tend to be sweeter?

A

D forms! –> bland or sweet
VS L forms: bland or bitter

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22
Q

L vs D flavor:
- Asp-NH2
- Glu
- His
- ILe
- Try

A
  • Asp-NH2: tasteless (L) vs sweet (D)
  • Glu: meaty (L) vs tasteless (D)
  • His: tasteless to bitter (L) vs sweet (D)
  • ILe: bitter (L) vs sweet (D)
  • Try: bitter (L) vs very sweet (D)
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23
Q

sugar is produced from ______ _____ or _____ _____
- production in 3 steps

A

from sugar cane or sugar beet
1. sugar cane crushed to expel flui/juice
2. sugar is crystallized out of fluid by evaporation –> thick dark syrupy liquid left behind = molasses
3. can further treat to refine by removing brown sugar to produce white sugar

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24
Q

the _______ after expressing juice out of sugar cane/sugar beet is known as _________ –> can be used as (2)

A
  • chalf
  • bagasse
  • animal feed or energy source
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25
Q

why does brown sugar cost the same as white sugar even if white is more refined (should be more expansive)?

A

because it is thought that brown sugar is healthier: contains polyphenols (antioxidant properties) and caramels (nutty flavor)

26
Q

what is invert sugar?
- sweeter than sucrose?
- how is it produced? (2)

A
  • invert sugar = mixture of glucose and fructose
  • sweeter than sucrose bc contains fructose
    1. enzymatic treatment by invertase (better than acid treatment)
    2. acid treatment: mineral acids like HCl –> can cause destruction of sugars
27
Q

name 9 traditional sweeteners

A
  • sugar
  • invert sugar
  • corn syrup
  • high fructose corn syrup
  • maltodextrin
  • honey
  • dates
  • maple syrup
  • molasses
28
Q

honey:
- made by what?
- mixture of (3)
- significant content of what?

A
  • honeybees
  • fructose (33-40%) + glucose (32-42%) + water (15-20%)
  • phenolics
29
Q

maple sugar
- mixcture of (3)
- obtained how?

A
  • glucose, fructose, sucrose
  • boiling sap of maple tree sugar
30
Q

molasses:
- what?
- has variable composition

A

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

31
Q

Sweeteners:
today’s challenge is to provide products that are (3)
- examples of used or approved for foods (7)

A
  • good tasting, sugar-free/low calorie, non cariogenic sweeteners
  • xylitol, mannitol, sorbitol, maltitol, lactitol, polydextrose, fruit juices
32
Q

7 criterias for selecting alternate sweeteners

A
  1. cariogenicity
  2. sweetness equivalent
  3. solubility and viscosity
  4. hygroscopicity
  5. heat of solution
  6. laxative effect
  7. cost
33
Q

do all sugars/sweetenvers have same level of cariogenicity?
- depends on (4)
- in general, cariogeneicity increase with (3)

A

NO!
- type + amount + physical state (liquid, solid, chewy, sticky) + how easily sugar is fermented into acids
- increases when sugar is more soluble + in liquid state + sticky

34
Q

give examples of sugars that are high cariogenicity, low and neutral/carbostatic

A
  • high: highly refined carbs (sucrose, white rice, white flour)
  • low: non refined carbs (whole grain, wheat bran, whole wheat)
  • carbostatic: foods that are basically sugar free
35
Q

we cannot avoid eating cariogenic foods
- 4 solutions

A
  1. eat food that furnish buffering capacity (and less carbs)
    - ie: proteins and peptides provide buffering capacity to maintain pH balance
    - cheeses can furnish Ca2+ ions that are important in tooth enamel formation
  2. eat chewing gums –> causes production of saliva that has components to maintain pH balance
  3. drinking water to wash out carbs/sugars that may be left in mouth or sticking to teeth
  4. intake of green tea that has high levels of catechins (antimicrobial agents) that inactivate/inhibit bacteria in mouth
36
Q

in general, _______ are resistant to fermentation or not fermented appreciably –> formation of cavity causing fermentation _______ _______ is minimal

A
  • polyols
  • plaque acids
37
Q

are animal or plant proteins better to protect from cariogenic foods?

A

animal! because contain less carbs than plan proteins

38
Q

sweetness equivalent of alternate sweetener
- generally concerned with ______ and _______ explain!

A
  • sweetness –> must be isosweet to sucrose = produce same level of sweet sensation as sucrose
  • quality –> no aftertastes
39
Q

why is solubility of sweeteners important?
- if not soluble, what happens?
- what is important characteristic of sweetener’s solubility?

A
  • sweeteners must dissolve in saliva to a minimum concentration that passes threshold value in order to impart sweet taste
    IF NOT SOLUBLE:
  • cannot taste it
  • can cause grainy/sandy sensation in mouth –> affects mouthfeel/texture
    RATE of solubility! –> if it takes too long to dissolve, different onset of perception of taste sensation
40
Q

solutes dissolve in water to influence _______
- large MW compounds
- vs low MW products

A

viscosity!
- large MW (ie polydextrose): can form thick syrupy products
- low MW (ie xylitol): can produce solutions that are less viscous than sucrose solutions = form products with thinner mouthfeel

41
Q

alternative sweeteners with low solubility result in products with a ________ mouthfeel

A

chalky

42
Q

what is hygroscopicity? ex.
- desirable?
- undesirable?
- examples of hygroscopicity food products?

A
  • capacity to bind/absorb moisture and retain it (ie gels/gums/gelatins, salt, rice, starch, sugar)
  • desirable: keeps food moist, juicy and succulent (ie fresh meats and other muscle foods)
  • undesirable: clumping of salts/sugars/coffee + sogginess of hard candies/chocolates
  • sea salt, sugar, rice, coffee, gelatin, guar gum, oatmeal
43
Q

hygroscopicity can affect _____A____ of a product
- (2 sweeteners) are non hygroscopic vs remaining ________ are
- high hydroscopic materials have low _____A_______ –> may require what?

A
  • shelf-stability
  • mannitol and isomalt
  • remaining polyols are hygroscopic
  • low shelf-stability –> require individual wrapping
44
Q

what is heat of solution?
- examples of foods that release vs absorb heat?

A
  • refers to energy/heat absorbed or released when solutes dissolve in solution
  • release: acid! ie eating hot chili peppers: feel heat and pain in mouth
  • absorbe heat: crystalline polyols (xylitol, mannitol, sorbitol), mint/eucalyptus –> cooling sensations in cheeks bc heat absorbed by cheeks
45
Q

explain laxative effect of sweeteners
- may be caused because compound …(3)

A

refers to situation where we ingest compounds that make it easy for use to ease ourselves
1. may be incompletely digested in GI tract (polyols, polydextrose)
2. may mix with food to produce softer stool (ie polydextrose)
3. may induce GI tract muscles to push out digested foods

*foods that have >50g sorbitol/day OR >20g mannitol/ day or >15g polydextrose/day are required to pose label warning statement concerning potential laxative effect

46
Q

why is cost a criteria for selecting alternate sweeteners?

A

because expansive alternate sweeteners can add to overall cost of food products
ie: polyols (xylitol) –> same sweetness as sucrose + not metabolize = no calories + antimicrobial effect –> BUT super expansive!

47
Q

compare relative cost/sweetness (??) from high to low
mannitol, isomalt, polydextrose, xylitol, maltitol, sorbitol

A

xylitol > maltitol > mannitol > sorbitol > isomalt > polydextrose

48
Q

mixing sweeteners will create sweetness ___________

A

synergism!
ie. 3:2 ratio of xylitol:sorbitol in chewing gum
4:1 ratio of maltitol:xylitol in chocolate produce/sugar-free products

49
Q

Name 4 types of natural high intensity sweeteners
+ 3 others

A
  • Xylitol
  • Miraculin
  • Thaumatin
  • Stevia
    + monellin, brazellin, neoculin
50
Q

XYLITOL:
- most commonly used ________ ________ –> ________ of them
- isosweet to ________
- aftertaste?
- how is it metabolized? = useful ingredient in what kinds of foods
- cause cavities?

A
  • polyphenol alcohols! –> sweetest of the polyols
  • isosweet to sugar
  • no discernible aftertaste
  • metabolized independently of insulin –> in diabetic foods
  • no bc resistant to fermentation by oral bacteria! –> does not cause pH decline to demineralize tooth enamel + cause tooth decay
51
Q

5 technical characteristics of xylitol

A
  1. high thermal stability
  2. high microbiological stability
  3. inhibits many food-spoilage organisms
  4. does not react with amino acids (no maillard reaction and no discolorations)
  5. moderate hygroscopicity
52
Q

4 applications of xylitol

A
  1. chewing gum and other confectionery –> cooling effect!
  2. in pharmaceuticals (syrups, chewable tablets)
  3. in oral hygiene products (toothpaste, mouthwash)
  4. diabetic foods
53
Q

in general __ amino acids tend to be sweet while __ isomers are bitter
- exception?
- which specific amino acid is 35x sweeter than sucrose? synthetic derivative?

A
  • D-aa = sweeter
  • L-aa = bitter
  • exception: D-Alanine has insipid taste and L-alanine has sweet taste
  • D-Try! –> 6-chloro-D-Try is 1000x sweeter than sucrose
54
Q

MIRACULIN:
- what type of molecule?
- from what food?
- found where?
- unusual property?

A
  • glycoprotein
  • berries from plant commonly known as miracle fruit
  • West Africa
  • of tasting intensely sweet only in presence of acids (no taste if just eat it by itself)
55
Q

THAUMATIN:
- what type of molecule ish?
- what food?
- from where?
- _______x sweeter than sucrose

A
  • mixture of sweet-tasting proteins –> hydrolysate
  • katemfe (a fruit)
  • from East Africa
  • 1500-2500x sweeter
56
Q

STEVIA:
- from what?
- found where?
- active compound

A
  • from shrub
  • tropical and sub-tropical zones of zones of Americas
  • steviol glycoside
57
Q
  • sour taste is due to ? (ie 4)
  • what are other contributory factors to sour taste (3)
  • what is another name for sour taste?
A
  • H+ ions from acid! (ie lactate, pyruvate, acetate, malate, etc.) –> [H+] determines degree of sourness, not the total acidity!!!
    1. nature of acidic group (ie: carboxyl group + FIND OTHERS)
    2. buffering capacity
    3. presence of other compounds
  • tartness
58
Q

give examples of organic vs inorganic acids

A

ORGANIC:
- acetic acid, citric acid, fumaric acid, lactic acid, tartaric acid, malic acid, benzoic acid, sorbic acid, adipic acid, propionic acid, succinic acid, succinic anhydride
INORGANIC:
- H3PO4 (phosphoric acid), HCl (hydrochloric acid)

59
Q

what type of acidulant should I add in milk products? vs sour dressing products
- which acids good for sodas?

A

you should add acids that are already naturally present in milk (ie lactic acid)
- vs use acetic acid in vinegar/sour dressing/mayo foods to impart similar flavor
- phosphoric acid = bland taste –> doesn’t impart any of its own flavors to products like sodas

60
Q

Phosphoric acid
- organic or inorganic?
- color? structure?
- commonly used in the form of a ______, _______ liquid with concentration ranging from ___-___%
- has a ______ taste which enables it to blend very well with _____-______ flavors
- used in formulating (3)

A
  • inorganic
  • colorless + crystalline solid
  • clear, syrupy liquid –> 75-85%
  • bland taste –> with non-fruit flavors
  • cola drinks + cheese making + brewing for pH control
61
Q

6 reasons to include acidulants in foods

A
  1. optimum acidity in desserts, sugar confectionery, fruit-flavored beverages (+ salad dressing, mayo) enhances flavor of product
  2. acid milieu curtails microbial activity/metabolism and prevents spoilage
  3. acid milieu slows down/stops action of several enzymes, preventing food spoilage by autolysis (+ prevents discoloration by PPO)
  4. acids enhance action of natural antioxidants
  5. important to have right acidic pH during wine processing to obtain stable products
  6. in pectin-based jams and jellies, gel strength depends on the use of the acidulant –> right texture!
    (also to achieve desired texture in cottage cheese)
62
Q

food spoilage caused by (2)

A
  1. microorganisms
  2. enzymes–> cause autolysis/breakdown or biomolecules

Food Chemistry 2 (7 decks)

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