Definitions

Question 1

flavour enhancers

Answer 1

• MSG enhances flavor
• substances contribute to umami taste of foods when used at levels in excess of their independent detection limits, and enhance flavours of foods at levels below their detection thresholds
• nucleotides

Question 2

essential oils

Answer 2

• volatile oils
• when exposed to air they evaporate at RT
• complex pictures of a wide variety of organic compounds [hydrocarbons, terpenes, alcohols, ketones, phenols, aldehydes, esters]
• obtained by steam distillation or solvent extract from many odorous plant sources
• organic constituents of EO are synthesized by plant during normal growth
• rich in character impact compounds

Question 3

resins and oleoresins

Answer 3

• natural products obtained either directly from plant as exudates or by alcohol extraction of plants that contain resinous material
• solids or semi-solids at RT
• soluble in alcohol or basic solutions, not water soluble
• complex oxidation products of terpenes
• oleoresins: resin mixed with gums an/or volatile oils

Question 4

astringency

Answer 4

• taste - related phenomena perceived as dry feeling in the mouth along with coarse puckering of the oral tissue due to TANNINS and POLYPHENOLS interacting with the proteins in saliva forming precipitates or aggregates
• desirable in tea and red wine

Question 5

pungency

Answer 5

certain compounds found in several spices and vegetables cause characteristic hot, sharp, burning and stinging sensations that are known collectively as pungency
-> capsaicinoids

Question 6

cooling effect

Answer 6

occurs when certain chemicals contact the nasal or oral tissues and stimulate a specific receptor. this effect is most commonly associated with mint-like flavours, including peppermint, spearmint and wintergreen
- menthol: terpenoid structure

Question 7

sweet

Answer 7

sweet taste is produced by several different classes of compounds:

1. sugars
2. polyhydric alcohols
3. alpha amino acids
4. synthetic sweeteners

Question 8

sour

Answer 8

results from the presence of hydrogen ions on the tongue, however sourness and acidity are not directly related, but there is some correlation. 2 acids having the same pH does not produce the same degree of response

Question 9

salty

Answer 9

salt taste is stimulated by most soluble salts having low molecular weights

Question 10

which are the 3 major classes of organic compounds associated with bitterness?

Answer 10

alkaloids, glycosides, and peptides

Question 11

what taste do tannic acids elicit? and what class of compound is it ?

Answer 11

astringent

polyphenolic

Question 12

what is a flavour note?

Answer 12

classification based on sensory properties and not on functional groups to which each component belongs
classification based on parent flavour charcateristics

Question 13

what is the most common flavour note?

Answer 13

the green grassy flavour note

Question 14

flavour sensation

Answer 14

psychological interpretation of a physiological response to a physical stimulus

Question 15

olfactory cells

Answer 15

NEURONS situated in upper part of the nasal cavity
their receptors located on cilia sapperform a similar function to that of taste cells through their own nerve fibres that transmit neural impulses from receptors directly to olfactory bulb in brain
=> DIRECTLY ATTACHED to brain

Question 16

taste receptors

Answer 16

found on surface of taste cells are linked to brain by way of CRANIAL NERVES which carry the nerve impulses to the brain after the neurotransmitters are released from taste cells => process initiated by the formation of the taste compound-receptor complex

Question 17

taste

Answer 17

sensation that food and other chemicals elicit when they stimulate receptors in the taste buds

Question 18

olfactory epithelium

Answer 18

of nasal cavity, responsible for detecting volatile stimuli that are present in the air or emanates from the food in the mouth

Question 19

odorant binding protein OBP

Answer 19

complex protein produced in olfactory mucosa acts as a chemical messenger that carries lipophilic volatile compounds into the olfactory epithelium
when OBP binds to the lipophilic volatile compounds the OBP-odor complex binds to the receptor sites that elicit a response

Question 20

principle of vibrational assisted olfaction

Answer 20

odorant molecule with characteristic frequency Wo binds to the olfactory receptor binding pocket forming an electron-donor-acceptor complex with donor energy Ed and acceptor energy Ea. Electron tunnelling from donor site to acceptor site of olfactory receptor is enhanced If the vibrational frequency of the odorant molecule matches the energy difference DE=Ed-Ea

Question 21

target molecule

Answer 21

the molecule to be synthesized

Question 22

disconnection

Answer 22

an imaginary bond breaking corresponding to the reverse of a real reaction

Question 23

functional group interconversion FGI

Answer 23

the process of interconverting one functional into noter during retrosynthetic analysis

Question 24

synthesis backwards

Answer 24

the process of breaking down a target molecule into available starting materials by disconnection of FGI

Question 25

retro synthetic arrow

Answer 25

a double line arrow used to indicate the reverse of a synthetic reaction

Question 26

synthon

Answer 26

an idealized fragment (usually a cation or anion) resulting from a disconnection, only exists on paper

Question 27

synthetic equivalent

Answer 27

a real chemical compound (reagent) carrying out the function of a synthon

Question 28

retrosynthesis

Answer 28

breaking/disconnecting a target molecule (molecule we want to synthesize in the lab) on the paper into two simpler fragments (synthons) in such a way that can be reconnected by a known chemical transformation
1. start by choosing an appropriate covalent bond in the target molecule and breaking it in such a way that one end of the bond should have a negative charge (nucleophilic end) and the other en a positive charge (electrophilic end) => resulting 2 parts of the molecules known as synthons

Question 29

alpha carbon

Answer 29

always the carbon next to carbonyl

Question 30

carbon 1

Answer 30

carbon involved in carbonyl

Question 31

carbon 2

Answer 31

alpha carbon

Question 32

beta carbon

Answer 32

carbon 3

Question 33

why can an Alpha carbon tolerate a negative charge

Answer 33

because of delocalization -> distribution of charge over a large surface area