The tongue detects a small set of basic tastes: sweet, sour, salty, bitter and umami. Everything else people call a flavour — blueberry, jasmine, chocolate, smoke — is smell. Aroma reaches the nose two ways: through the nostrils when you sniff, and from the back of the mouth up into the nasal cavity when you swallow and breathe out. The second route, retronasal smell, is why food loses its 'taste' when your nose is blocked.
The third sense is touch. The mouth feels weight, viscosity, oiliness, dryness and temperature. Body is a tactile sensation. So is astringency, the rough, puckering dryness of strong tea or unripe fruit, which is often mistaken for bitterness.
The brain merges all three into one impression, which is why untrained tasters describe everything at once and find it hard to say what they are tasting. The basic skill of tasting is pulling the impression back apart: what is the tongue reporting, what is the nose reporting, what is the mouth feeling?
Three senses make one flavour
CoffeeHQ diagram
Taste — the tongue
Sweet
Sour
Bitter
Salty
Umami
A small fixed set. Acidity and bitterness live here.
Smell — the nose
Fruity
Floral
Nutty and cocoa
Roasted
Spice
Fermented
Everything specific. Reached by sniffing and, mostly, from the back of the mouth.
Touch — the mouth
Body or weight
Texture
Astringency
Temperature
Not tastes at all. Astringency is the one most often mistaken for bitterness.
The standard division of flavour perception in sensory science. The aroma families shown are the broad groups used on coffee flavour wheels.
Formal tasting separates a cup into a few attributes. The exact list differs between systems; these are the common core.
Aroma
What you smell, dry and wet. Usually the most distinctive thing about a coffee and the first to fade as it stales.
Acidity
The bright, lively quality. Good acidity reads as fruit-like and juicy; too much, or the wrong kind, reads as sour or vinegary. It is a sensory quality and not a pH reading.
Sweetness
Roasted coffee contains little sugar, so perceived sweetness comes largely from aroma and from the absence of harshness. It is a mark of ripe fruit and good roasting.
Bitterness
Present in all coffee, from caffeine and from compounds formed in roasting. A little gives structure; a lot dominates. It rises with darker roasts and higher extraction.
Body and texture
The weight and feel of the liquid: thin, silky, creamy, syrupy, heavy. Shaped by concentration, oils and suspended fines, and so by brewing method as much as by the coffee.
Finish
What remains after swallowing, and for how long. Clean and sweet, or drying and lingering.
Balance and clarity
Whether one attribute overwhelms the others, and how easily separate flavours can be picked out.
The Coffee Taster's Flavor Wheel, published by the Specialty Coffee Association with World Coffee Research in 2016, arranges coffee aromas from general families at the centre — fruity, floral, sweet, nutty and cocoa, spices, roasted, green and vegetative, sour and fermented, and others — out to specific descriptors at the rim. It is built on a sensory lexicon in which each term is tied to a physical reference that anyone can smell.
Use it from the centre outwards. First decide the family: is this fruity, or nutty, or roasted? Then, if you can, narrow it: berry or citrus or dried fruit? Only then reach for the specific word. Stopping at the family is entirely respectable; most of the value is in getting the family right.
Tasting notes on a bag are produced this way and are comparisons, not ingredients. 'Blueberry' means that some aroma compounds in the coffee resemble those in blueberries to the person who wrote the note. Another taster may reach for a different fruit, and both can be right.
A handful of faults account for most bad cups. Stale coffee tastes flat, papery or like cardboard, with little aroma. Over-fermented coffee tastes of vinegar or rotting fruit. Under-developed roasts taste grassy or like raw grain; over-roasted coffee tastes ashy, smoky or burnt. Old green coffee tastes woody. Mould gives a musty, earthy taint, and a phenolic defect gives a medicinal, antiseptic note.
It helps to sort faults by where they arose, because that decides whether brewing can do anything about them. Sour-and-thin or bitter-and-drying are usually brewing. Flat and papery is age. Grassy, ashy or baked is roasting. Vinegar, mould and medicine come from the farm or the mill. Only the first group is yours to fix.
Your task. Taste one coffee and fill in the single-coffee worksheet. Rate each attribute first, then use the flavour-family questions to choose a family before you look at the bag's tasting notes.
What to notice. The worksheet asks for attributes before descriptors, in the same order as this level. Your note is recorded as your own observation and nothing else.
Exercise: Calibrating the basic tastes
Objective. Learn to tell sour from bitter from astringent, which most people confuse in coffee.
You will need
Four glasses of water
A pinch of sugar, a few drops of lemon juice, a pinch of salt, and strongly over-steeped black tea
A cup of brewed coffee
Keep the same
Make each solution weak — just strong enough to recognise
Rinse with plain water between tastes
Procedure
Make four glasses: sugar in water, lemon in water, salt in water, and the over-steeped tea.
Taste each and note where and how you feel it, and how long it lasts.
In the tea, separate the bitter taste from the drying, rough feeling on the tongue and cheeks.
Now taste the coffee and name which of those sensations are present.
Add a few drops of the lemon solution to a little coffee, and a few grains of sugar to another, and taste the change.
What to notice
Is sourness quick and sharp for you, and bitterness slower and at the back?
Can you feel astringency as a texture rather than a taste?
Which sensation did you previously call 'bitter' that was actually sour or drying?
Reading what you found
Sour, bitter and astringent are three different things: two tastes and one tactile sensation. Under-extracted coffee is typically described as sour and over-extracted coffee as bitter and astringent, so being able to tell them apart is the basis of every troubleshooting decision in brewing.
What this cannot show
Kitchen solutions are uncontrolled; sensory training kits use measured concentrations.
People differ in sensitivity to bitterness for genetic reasons, so your threshold is not anyone else's.
A protocol for you to run. CoffeeHQ has not run it and reports no result from it.
A friend describes a light-roasted filter coffee as 'really bitter' and pulls a face. You taste it and find it sharp and lemony, with almost no bitterness at all.
Reasoning it out
Many people use 'bitter' for any unpleasant intensity in coffee.
Sharp, lemony and mouth-watering describes sourness, a different basic taste.
The distinction matters practically: sourness suggests under-extraction, bitterness the opposite, and the remedies point in opposite directions.
Asking where in the mouth and how quickly the sensation arrives usually separates them.
What to do
Offer a reference: a drop of lemon juice in water for sour, over-steeped tea for bitter and drying. Once the words are attached to sensations, 'too bitter' usually becomes 'too sour', and the fix becomes a finer grind.
Sensory vocabulary is calibrated by tasting reference samples alongside other people. A page can give you the framework; it cannot tell you whether what you call 'citrus' is what a trained panel calls citrus.
World Coffee Research variety and agronomy resources — World Coffee Research (WCR)
Coffee Quality Institute Q Grader / cupping standards — Coffee Quality Institute (CQI)
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