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Food Chemistry > 12 Flavor > Flashcards

12 Flavor Flashcards

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1
Q

Respective flavor type for each body part (nose, mouth and tongue)

A

odour, trigeminal, taste

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2
Q

Flavor components based on oral chemoreception (taste)

A
  1. Oral chemical
    trigeminal irritation sensation
  2. Gustation
    Sweet, sour, bitter, salty, umami
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3
Q

Flavor components based on nasal chemoreception (smell)

A
  1. Olfaction
    Sensations from volatiles, sniffed (aroma), or from the mouth retronasally (flavor)
  2. Nasal chemical irritation
    Trigeminal sensations
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4
Q

Role of volatile flavor

A

Aroma, contributing on smell
Receptors: olfactory and nasal cavity

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5
Q

Role of non-volatile flavor

A

Contributes to taste
Receptor: taste buds in the tongue

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6
Q

Flavor properties that can be detected by sensory

A
  • above treshold concentration (!! so not all volatile components contribute to the flavor)
  • volatile for volatile flavors
  • dissolve in mucosa
  • interact with olfactory nerve
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7
Q

Aroma components which give aroma characteristic of a food

A

character impact compounds/arome active compounds

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8
Q

Classification of aroma impact compounds

A

Group 1
aroma dominated by 1 compound (eg banana)

Group 2
mix of several compounds (eg apple_

Group 3
very complex aroma, but can be synthesized (eg onion)

Group 4
very complex aroma that cant be synthesized (eg coffee)

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9
Q

Classification of odorants

A
  1. TYPE (meaty, fruity, spicy, minty)
  2. RATE OF APPEARANCE (top note [fast, most volatile], middle note [medium], base note [slow])
  3. GROUP RELATED (primary odour)
  4. AROMA DESCRIPTION SYSTEMS (first, second, third tier)
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10
Q

How does molecule geometry affect aroma

A

Odorants with different molecule geometry have different receptor binding site

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10
Q

Factors of correlation between structure and aroma

A
  1. molecule geometry
  2. enantiomers
  3. different chemical structure, similar odor
  4. similar chemical structure, different odor
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11
Q

Aroma of linalool enantiomers

A

(R) woody, lavender
(S) sweet, lavender

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12
Q

Aroma of 1-octen-3-ol enantiomers

A

(R) mushroom odor
(S) natural citronella type

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13
Q

Aroma of citronellol enantiomers

A

(R) citronella like top note
(S) floral, rose-like

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13
Q

Aroma of nootkaton enantiomers

A

(R) grapefruit
(S) woody, spicy

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14
Q

Aroma of limonen enantiomers

A

(R) orange
(S) turpentine-like

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15
Q

Aroma of carvone enantiomers

A

(R) Spearmint
(S) Caraway

16
Q

Compounds that give a similar musk odour

A

tricyclic compounds
macrocyclic ketones
lactones
steroids
nitrocyclohexanes
indanes
tetra hydronaphtalenes
acetophenoses

17
Q

Flavor compounds produced from enzymatic fermentation reactions

A

Ester
Acid
Carbonyl
Alcohol
Terpene
Lactone
Pyrazine

18
Q

Steps of Maillard reaction

A
  1. The reducing sugar reacts with amino acid to form a Schiff base (glycosylamine)
  2. Amadori rearrangement will change unstable
    glycosylamine into intermediate products.
  3. The intermediate products will be involve in a complex reaction (strecker degradation and fragmentation) to form volatile compounds and melanoidins.
19
Q

How does temperature affect Maillard rxn

A

Reaction increases as temp increases

20
Q

How does type of sugar affect Maillard rxn

A

Reactivity pentose > hexose > disaccharide ? trisaccharide

21
Q

How does type of amino acid affect Maillard rxn

A

Reactivity lysine > aspargine > cysteine

22
Q

Optimum Aw for Maillard reaction

A

0.7 - 0.8

23
Q

How does pH affect Maillard rxn

A

low pH: dominated by hydroxymethylfurfural (HMF)
high pH: dominated by furfural

24
Q

Flavor compounds resulted by Maillard rxn

A

Pyrazine (roasted, burnt, grilled, animal flavor)
Methoxypyrazine
Pyrrole (sweet, corn-like caramel flavor)
Pyridine (green notes flavor)
Pyrroline
Pyrrolidine
Pyrrolizine
Piperine

25
Q

What is responsible for the roasted/burnt/frilled animal flavor from Maillard reaction

A

pyrazine

26
Q

What is responsible for the sweet, corn like caramel flavor from Maillard rxn

A

Pyrrole

27
Q

Strecker degradation reaction

A

alpha diketone + amino acid -> alpha amino ketone

e.g. formation of pyrrole from Maillard intermediate compounds + proline and hydroxyproline

28
Q

Reaction of hetercocyclic compounds with sulfur

A

Condensation, cyclization

mostly thiazole and thiophene

29
Q

Products of rxn of heterocyclic compounds with sulfur from maillard rxn

A

thiazole (green, nutty, roasted, vegetable, meaty notes)

thiophene-2-carboxaldehyde (almond-like)

5-methylthiophene-2-carboxalde (cherry-like)

30
Q

Reaction of heterocyclic compounds with oxygen

A

cyclization of intermediate maillard product

31
Q

Products of heterocyclic compounds with oxygen in maillard rxn

A

maltol (sweet)
furaleol (strawberry like)
Cyclotone (caramel like)
oxazole (green, sweet, floral, vegetable like)
oxazoline (green sweet floral vegetable like)

32
Q

Steps for flavor analysis

A
  1. flavor compound isolation
  2. separation of targeted compounds
  3. fractionation
  4. identification (GC-MS, GC-IR, GC-O, GC-MS-O, GC with specific detector NPD, FPC, AED)
33
Q

How is flavor compound isolation done

A
  • sample size reduction
  • sample homogeneity requirements (eg fruit ripening stage or animal age)
  • enzyme inactivation
34
Q

Explain the headspace method

A

Sample is put in air tight closed chamber, volatile compounds in headspace taken by gas tight syringe then injected to gas chromatography

35
Q

Advantage and disadvantage of headspace methods

A

Advantage
Limited artifact formation because isolation does not involve high temp

Disadvantage
Only flavor with high volatility (top notes) is isolated

36
Q

Explain the volatile absorption method

A
  1. Spray inert gas to food sample to push out flavor from food matrix
  2. Flavor absorbed by certain polymer (Tanax GC, Proparax Q, Chromosorb 105)
  3. Flavor recovery
  4. Flavor injection to gC
37
Q

Adv and disadv of volatile absorption methods

A

Adv
minimal artifact formation

disadv
- only flavor with high volatility (top noted) and suitable with absorber is isolated
- isolate may contain water

38
Q

Explain distillation extraction method (Likens-Nikerson)

A

Simultaneous distillation of water, flavor compounds, organic distillation and condensation

Separation based on density

39
Q

Adv and disadv of distillation extraction (Likens-Nikerson)

A

Adv
- Solvent used reduce artifact formation
- volatile compounds highly extracted (top notes and base notes)

disadv
- Water is extracted
- artifact formation still occur

40
Q

Explain solvent extraction method

A

Principle: like-dissolves-like, maceration, percolation, refluc

Food Chemistry (5 decks)

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