12 Flavor Flashcards
Respective flavor type for each body part (nose, mouth and tongue)
odour, trigeminal, taste
Flavor components based on oral chemoreception (taste)
- Oral chemical
trigeminal irritation sensation - Gustation
Sweet, sour, bitter, salty, umami
Flavor components based on nasal chemoreception (smell)
- Olfaction
Sensations from volatiles, sniffed (aroma), or from the mouth retronasally (flavor) - Nasal chemical irritation
Trigeminal sensations
Role of volatile flavor
Aroma, contributing on smell
Receptors: olfactory and nasal cavity
Role of non-volatile flavor
Contributes to taste
Receptor: taste buds in the tongue
Flavor properties that can be detected by sensory
- above treshold concentration (!! so not all volatile components contribute to the flavor)
- volatile for volatile flavors
- dissolve in mucosa
- interact with olfactory nerve
Aroma components which give aroma characteristic of a food
character impact compounds/arome active compounds
Classification of aroma impact compounds
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)
Classification of odorants
- TYPE (meaty, fruity, spicy, minty)
- RATE OF APPEARANCE (top note [fast, most volatile], middle note [medium], base note [slow])
- GROUP RELATED (primary odour)
- AROMA DESCRIPTION SYSTEMS (first, second, third tier)
How does molecule geometry affect aroma
Odorants with different molecule geometry have different receptor binding site
Factors of correlation between structure and aroma
- molecule geometry
- enantiomers
- different chemical structure, similar odor
- similar chemical structure, different odor
Aroma of linalool enantiomers
(R) woody, lavender
(S) sweet, lavender
Aroma of 1-octen-3-ol enantiomers
(R) mushroom odor
(S) natural citronella type
Aroma of citronellol enantiomers
(R) citronella like top note
(S) floral, rose-like
Aroma of nootkaton enantiomers
(R) grapefruit
(S) woody, spicy
Aroma of limonen enantiomers
(R) orange
(S) turpentine-like
Aroma of carvone enantiomers
(R) Spearmint
(S) Caraway
Compounds that give a similar musk odour
tricyclic compounds
macrocyclic ketones
lactones
steroids
nitrocyclohexanes
indanes
tetra hydronaphtalenes
acetophenoses
Flavor compounds produced from enzymatic fermentation reactions
Ester
Acid
Carbonyl
Alcohol
Terpene
Lactone
Pyrazine
Steps of Maillard reaction
- The reducing sugar reacts with amino acid to form a Schiff base (glycosylamine)
- Amadori rearrangement will change unstable
glycosylamine into intermediate products. - The intermediate products will be involve in a complex reaction (strecker degradation and fragmentation) to form volatile compounds and melanoidins.
How does temperature affect Maillard rxn
Reaction increases as temp increases
How does type of sugar affect Maillard rxn
Reactivity pentose > hexose > disaccharide ? trisaccharide
How does type of amino acid affect Maillard rxn
Reactivity lysine > aspargine > cysteine
Optimum Aw for Maillard reaction
0.7 - 0.8
How does pH affect Maillard rxn
low pH: dominated by hydroxymethylfurfural (HMF)
high pH: dominated by furfural
Flavor compounds resulted by Maillard rxn
Pyrazine (roasted, burnt, grilled, animal flavor)
Methoxypyrazine
Pyrrole (sweet, corn-like caramel flavor)
Pyridine (green notes flavor)
Pyrroline
Pyrrolidine
Pyrrolizine
Piperine
What is responsible for the roasted/burnt/frilled animal flavor from Maillard reaction
pyrazine
What is responsible for the sweet, corn like caramel flavor from Maillard rxn
Pyrrole
Strecker degradation reaction
alpha diketone + amino acid -> alpha amino ketone
e.g. formation of pyrrole from Maillard intermediate compounds + proline and hydroxyproline
Reaction of hetercocyclic compounds with sulfur
Condensation, cyclization
mostly thiazole and thiophene
Products of rxn of heterocyclic compounds with sulfur from maillard rxn
thiazole (green, nutty, roasted, vegetable, meaty notes)
thiophene-2-carboxaldehyde (almond-like)
5-methylthiophene-2-carboxalde (cherry-like)
Reaction of heterocyclic compounds with oxygen
cyclization of intermediate maillard product
Products of heterocyclic compounds with oxygen in maillard rxn
maltol (sweet)
furaleol (strawberry like)
Cyclotone (caramel like)
oxazole (green, sweet, floral, vegetable like)
oxazoline (green sweet floral vegetable like)
Steps for flavor analysis
- flavor compound isolation
- separation of targeted compounds
- fractionation
- identification (GC-MS, GC-IR, GC-O, GC-MS-O, GC with specific detector NPD, FPC, AED)
How is flavor compound isolation done
- sample size reduction
- sample homogeneity requirements (eg fruit ripening stage or animal age)
- enzyme inactivation
Explain the headspace method
Sample is put in air tight closed chamber, volatile compounds in headspace taken by gas tight syringe then injected to gas chromatography
Advantage and disadvantage of headspace methods
Advantage
Limited artifact formation because isolation does not involve high temp
Disadvantage
Only flavor with high volatility (top notes) is isolated
Explain the volatile absorption method
- Spray inert gas to food sample to push out flavor from food matrix
- Flavor absorbed by certain polymer (Tanax GC, Proparax Q, Chromosorb 105)
- Flavor recovery
- Flavor injection to gC
Adv and disadv of volatile absorption methods
Adv
minimal artifact formation
disadv
- only flavor with high volatility (top noted) and suitable with absorber is isolated
- isolate may contain water
Explain distillation extraction method (Likens-Nikerson)
Simultaneous distillation of water, flavor compounds, organic distillation and condensation
Separation based on density
Adv and disadv of distillation extraction (Likens-Nikerson)
Adv
- Solvent used reduce artifact formation
- volatile compounds highly extracted (top notes and base notes)
disadv
- Water is extracted
- artifact formation still occur
Explain solvent extraction method
Principle: like-dissolves-like, maceration, percolation, refluc
