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Taste Chemistry
Terry Acree
Taste has only six distinct percepts: salt, sour, sweet, umami, bitter and chemesthesis. ...
| Percept | Receptor | Ligand |
| salt | ENaC | soduim |
| sour | hydrogen ion receptor | hydrogen ion |
| sweet | T1R3 and T1R3 | sugars (AH-B) |
| sweet | T1R2 and T1R3 | artificial sweeteners |
| umami | T1R1 and T1R3 | glutimate, etc. |
| bitter | T2Rs (30) | organic bases |
| astringency | trigeminal | phenolics |
by harry Lawless
Taste qualities:
Sweet - carbohydrates with AH,B system
primarily glucose and fructose, secondarily ethanol and glycerol
salty - Na+, Li+
bitter - lipophilic molecules such as catechin
(flavanoid phenolics, tannin monomers)
secondarily, terpenes, glyclosides, alkaloids
Individual differences are important - e.g. PTC dimorphism.
umami taste? sources: monosodium glutamate. broth: kombu (sea tangle)
ribonucleotide salts in katsuobushi (dried bonito), and shiitake (mushroom)
Are there only four tastes?
what about metallic, astringent, alkaline, insipid, pungent, biting?
Theories of sourness
sour - hydrogen ions from acids, tartaric and malic, citric, acetic, lactic.
anion effects may include titration off of undissociated molecules:
At equal pH, acetic acid is more sour that HCl.
Given a 5mM solution of HCl, it takes 64mM acetic acid to evoke an equal response from rat taste nerves. The relative pH of the two solutions is 2.3 and 3.0.
both pH and titratable acidity are required to predict sourness
some confusion in the literature regarding sour taste vs. "acid" taste
(not to be confused with volatile acidity)
Taste Adaptation:
After adaptation to different tastants, water takes on various tastes
Sequential effects and rinsing are influential!
Other factors -
temperature
mixture effects - generally suppressive
salivary flow - buffering and dilution
color biases - learned associations
retronasal smell mislabeled as tastes - "sweet" odors
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FS430: Understanding Wine and Beer