Unit 1 Flashcards
Molecules that contain heteroatoms such as nitrogen, oxygen and sulphur usually have ___________
Aroma properties
6-carbon membered ring =
cyclohexane
Aromatic molecules are not necessarily aromatic, they need to have __________ bonds
conjugated double
T or F: Benzene is a 6-membered ring with 3 double bonds
T
alkene =
alkyne =
double bonds
triple bonds
Elimination reactions will form a _______ bond
double
Oxidation reaction is when the reaction _________ the oxygen content
increases
Flavor chemistry includes 4 things:
1) synthesis
2) formation
3) food applications
4) analysis
T or F: Nose is not the only way to absorb volatile compounds
T
Name the 3 aspects of a flavor sensation:
1) Odor (low or high boiling compounds with odor effects)
2) Taste (non-volatile compounds with taste sensation)
3) Chemesthesis (non-volatile compounds that cause hot or cold sensations or textile effects)
T or F: Odor is the first thing we observe about the food, sense the volatile compounds that are emitting from thee food (aroma chemicals)
T
Smell and taste are __________ senses
chemical
Hot and cold sensations are sensed with the ___________ in our mouth, pungent, hot, cool; trigeminal senses
nerve endings
Aromatic chemicals are drawn up the nose in a stream of inhaled air to the ________________
olfactory neurons
These mucus-bathed neurons are tipped with frondlike cilia that carry receptors for odor molecules:
olfactory neurons
When molecules bind to their specific receptors, messages are sent along the neurons to the ________________ at the brain’s base and these to various obtain regions for interpretation
olfactory bulb
What we think of as taste is actually a combination of _______ and ______
taste and smell
Each taste buds has many taste _____
cells
Aroma volatiles entering through the nose = orthonasal pathway to olfactory bulb same destination as the volatiles emitted in our our mouth (retronasal):
receptors located in the olfactory bulb
The sensation elicited depends on the ___________ present on the molecule
functional groups
The map of the different types of tastes is _______. Any taste bud will capture any taste molecule if the molecule (shape, etc) can bind to the taste bud
no longer valid
T or F: Olfactory neurons are the only neurons exposed to the outside environment (olfactory bulb), important to smell food, danger, etc
T
T or F: Only 1-2% of these aromas will bind to receptors
T
More than _____ types of neurons in reality, each type occurs in a section of the brain called __________
300
glomerulus/glomeruli
Give a brief explanation on how the olfactory system works:
1) Odorants bind to odorant receptors
2) Olfactory receptor cells are activated and send electric signals
3) The signals are relayed in glomeruli
4) The signals are transmitted to higher regions of the brain
T or F: Nose and mouth have different centers in the brain but they are very close in proximity
T
Every time we exhale, we expel nitrogen, carbon dioxide, oxygen as well a host of ____________ (VOCs), the composition and concentration of which changes depending on our state of health
volatile organic compounds
________ is the most important factor in the acceptance of a new food product
flavor
Thousands of new food products are introduced yearly into the north American food markets; each new product can cost the food company $2-3 million to develop and stock the shelves of the supermarkets. However, within six months of their introduction _____ of the products fail. Most of those failures are due to deficiencies in flavor
80%
Name in order of importance the factors contributing to the success of a new product:
1) Flavor
2) Nutrition
3) Health
4) Texture
5) Mouthfeel
The flavor industry is affected by consumer perception and preferences:
- healthy foods
- ethnic flavors
- low salt
- natural flavors
- microwave, space tourism food
- low sugar
T or F: plant-based proteins do not follow the same flavor profile as animal proteins, not as well developed, keep formulating with thousands of chemicals
T
Flavor generating compounds can be divided into 2 groups:
volatile and non-volatile
Properties of the _____ also influence the rate at which particles of various sizes are selected for chewing (known as the selection function)
matrix
the physical properties of the peanuts influence the extent of breakage when the teeth make contact with the particles (known as the ___________)
breakage function
The overall flavor of foods is due to __________, ________ and ________, however specific flavors can be elicited by numerous other classes of compounds, such as alcohols, aldehydes, ketones and various heterocyclic compounds (pyrazines, pyrroles, pyridine, etc)
- carbohydrates
- lipids
- proteins
- pyrazines
- pyrroles
- pyridines
heterocyclic compounds
Carotenoids and simple terpenoids =
isoprenoids
- coumarines
- tannins
- flavonoids
- anthocyanines =
phenolics
Carotenoids are ______________
tetraterpenes
Monoterpenes have __ carbons (isoprene)
5
important for the generation of colors in different food products and have antioxidant properties =
carotenoids
- limonene
- menthol
- myrcene =
monoterpenes
Condensed tannins or _________
proanthocyanidines
Flavanol = ________, found in green tea, black tea, health promoting, antioxidant compounds
cathecin
Combination of all flavor =
flavor profile
The more character impact compound found in a product, the more easily we can _______________
reproduce flavors
Flavor components in food, range in number from _______ compounds in fresh products such as fruits and vegetables and to more than double of this number in foods subjected to heat or enzyme treatment; for example more than 700 compounds have been reported in roasted coffee aroma
50-250
Roasting and processing allows it to reach close to ________ flavor compounds
2000
Flavor sensation is produced by a group of chemicals constituting the __________
flavor profile
In some cases a single chemical known as _________________ generates a specific aroma note characteristic of the food, such as _______ for the vanilla flavor. These chemicals play an important role in defining the particular flavor profile
character impact
vanillin
key odorants =
aroma active compounds
The _________ changes the threshold value
type of solvent
T or F: Meta-analysis data now shows characteristic ratios of only about 3-40 genuine key odorants for each food, from a group of about 230 our of circa 10,000 food volatiles
T
Wine flavors and taste are really hard to ____ (usually more than 500 chemicals in them)
mimic
The taste and feel of the Italian wine amarone can be reproduced with only __ chemical compounds
35
Explain the aroma profile of different citrus oils:
They have the same components but with different concentrations
Profile = combination of different aroma chemicals in
different concentrations
The lowest concentrations at which an aroma chemical can be detected:
aroma detection threshold
Different aroma chemicals have different threshold values. It has been estimated that as few as eight molecules are required to trigger one human olfactory neuron and that ___ molecules can produce an identifiable sensation
40
_________________ which gives grapefruit aroma has a detection threshold of 0.0001 ppb or 0.0001 mg on 1000 L of water
1-p-menthene-8-thiol
Heterocyclic compounds contain atoms other than _______
carbon
Pyrazine is often the parent compounds: parent compound has a _______ threshold valie
higher
Gives some examples of how pyrazine reacts in food:
- nutty
- roasted
- maillard reaction
- typical toasted/cooked flavor
- they constitute one of the most important flavor impact compound in their profile
Aroma detection thresholds depend on the ________ used in the experiment. Sugars are polar and they will dissolve well in water
solvent
T or F: Some aroma chemicals have more than one threshold values, since the odor quality may change with concentration
T
Trans-non-2-enal for example possesses a ________ character just above 0.1 ppb value, above 8 ppb it smells ________ and above 30 ppb it becomes ________________. In aqueous solution at 1000 ppb it has a strong flavor of cucumber
woody
fatty
unpleasant or rancid
2-pentyl furan smells beany when diluted at 1-10ppm in oil, but when smelled without dilution it elicits the distinct aroma of ________
liquorice.
___________ of aroma compounds in a specific medium (water or oil) plays an important role in determining their thresholds values. The more lipophilic a molecule, the less soluble it will be in water and higher will be the vapor pressure above water therefore easily inhaled. The opposite is also true.
Volatility
What amino acid has an indole side chain:
tryptophan
Concentrated indole smells like ______, diluted indole has fragrant smell and is used in perfumery and in chocolate
feces
Some compounds can interfere with the detection of aroma compound and some can enhance the ability of aroma compounds to be detected. The former is known as _________ and the latter is known as _____________
- antagonism
- synergism
The ____________ for example has a distinct green bean aroma at 1 ppm in oil. In the presence of equal amount of _______________ it elicits no odor or taste. Thus the antagonist decadienal interferes with the detection of hexenal.
cis-hex-3-enal
trans, trans-deca-2,4-dienal
T or F: when fruits are mature they have great aroma properties
T
Flavors can be __________________ naturally in foods, such as apples, bananas and other fruits and vegetables or they can be produced from precursors during processing or ______________ such as baking, roasting and frying, furthermore flavors can be generated by enzymatic modifications such as in cheese or by microbial fermentation as in butter.
biosynthesized
thermal treatment
Ready-made flavors could be:
compounded or natural extracts
What are the 3 subcategories of ready-made flavors that are compounded:
- mixed
- from synthetic components
- from natural components
To formulate a specific flavor you have in your disposal the following components :
- single chemicals
- reaction flavors (flavors that we generate by reactions)
- concentrated fruit juices
- essential oils
- spices and herbs
- resins and oleoresins
- condiments (taste modifiers)
Compounds like monosodium glutamate (MSG) that enhances flavor. The actual mechanism of flavor enhancement is not known. These substances contribute a delicious or umami taste to foods when used at levels in excess of their independent detection limits, and enhance flavors of food at levels below their detection thresholds. Their effects are prominent and desirable in the flavors of vegetables, dairy products, meats, poultry and fish. Examples: monosodium glutamate, 5’-ribonucleotides such as 5’-inosine monophosphate (5’-IMP) and maltol (used for sweet foods and fruits):
Flavor enhancers
_________________ such as lemon and cinnamon are rich in flavor impact compounds. (GC/MS) can be used to analyze them
Essential oils
Essential oils are also known as volatile oils, or essences. When exposed to air they __________ at room temperature. They are usually complex mixtures of a wide variety of organic compounds (such as hydrocarbons - terpenes - alcohols, ketones, phenols, aldehydes, esters, etc). Essential oils are obtained by ________________ or solvent extraction from many odorous plant sources such as clove, cinnamon, orange, lemon, jasmine, rose, etc. The organic constituents of essential oils are synthesized by the plant during its ________________
evaporate
steam distillation
normal growth
T or F: resins are soluble in alcohols
T
___________ are natural products that can be obtained directly from the plant as exudates or are prepared by alcohol extraction of plants that contain resinous materials
resins
Naturally occurring resins are ______ or __________ at room temperature. They are soluble in alcohol or basic solutions but insoluble in _________
solids
semi-solids
water
T or F: resins are usually non-crystalline and soften or melt on heating
T
T or F: chemically resins are complex oxidation products of terpenes
T
T or F: resins rarely occur in nature without being mixed with gums and/or volatile oils forming oleoresins
T
Taste related phenomena perceived as a dry feeling in the mouth along with a coarse puckering of the oral tissue, this is due to tannins or polyphenols interacting with the proteins in the saliva to form precipitates or aggregates:
Astringency
Astringency may be a desirable flavor property such as in ________ and _________
tea and red wine
Certain compounds found in several spices and vegetables cause characteristic hot, sharp, burning and stinging sensations that are known collectively as ________________
pungency
__________________ occur when certain chemicals contact the nasal or oral tissues and stimulate a specific receptor. This effect is most commonly associated with mint-like flavors, including peppermint, spearmint and wintergreen
Cooling sensations/effect
Sweet taste is produced by several different classes of compounds:
- sugars
- synthetic sweeteners
- alpha amino acids
- polyhydric alcohols
Sour taste results from the presence of _______________ on the tongue, however, sourness and acidity (pH) are not directly related, but there is some correlation. Two acids having the same pH does not produce the same degree of response
hydrogen ions
Salt taste is stimulated by most __________________ having low molecular weights
soluble salts
Threee major classes of organic compounds encountered in food materials are associated with bitterness:
- alkaloids
- glycosides
- peptides
