Unit 2: The Families in Depth · Module 12
Tannins & Polyphenols — The Structural Ones
You don't smell tannins. You feel them. That dry, grippy, puckering sensation in a mouth. They're the frame that holds everything else up. Without structure, a bitters formula are just aromatic water.
01 · The Personality
Dry, structural, and felt rather than tasted. The skeleton of the drink.
Tannins and polyphenols are large, heavy molecules. They have very high molecular weights (often 500-3,000 Da, compared to limonene at 136 Da). This means they're non-volatile. They don't evaporate at room temperature. You will never smell a tannin. They don't reach your olfactory receptors because they're too heavy to become a gas.
Instead, tannins work through a completely different mechanism. They bind to proline-rich proteins in a saliva. When those salivary proteins get bound up, your saliva loses its lubricating ability. The mucous membranes in a mouth feel drier, rougher, grippier. This is astringency, and the trigeminal nerve detects it as a tactile sensation, not a taste or a smell.
Think of strong black tea with no milk. That dry, puckering feeling? Tannins. Red wine that makes your gums feel tight? Tannins. Unripe banana with that chalky, starchy mouthfeel? Tannins binding to salivary proteins.
In formulation, tannins provide structure. They're the framing of the house. Without tannins, a bitters formula can have beautiful aromas (terpenes), warm spice (phenols), and genuine bitterness (alkaloids) but still feel "watery" or "thin" in the mouth. The tannins give it physical presence. They make the liquid feel like it has substance.
02 · Types You'll Work With
Not all tannins behave the same. Two major categories.
Hydrolyzable Tannins (Gallotannins, Ellagitannins)
Not aromatic · mild astringency · smooth
Found in oak bark, pomegranate, sumac, and chestnut. These break down in water and alcohol over time, which means their astringency softens with age. This is why oak-aged spirits become smoother: the hydrolyzable tannins from the barrel slowly degrade. In an extracts, these provide a gentler, rounder astringency that integrates well.
Condensed Tannins (Proanthocyanidins)
Not aromatic · stronger astringency · grippy
Found in grape seeds, tea, cherry bark, and many tree barks. These don't break down as easily. Their astringency is more persistent and aggressive. In a wild cherry bark extract, the condensed tannins are what provide that firm, dry grip in the finish. They work well for bitters but can become harsh if over-extracted. This is why extraction time matters: longer isn't always better with tannin-rich botanicals.
Anthocyanins (a specific polyphenol)
Not directly aromatic · contribute color · mild astringency
The pigments responsible for the deep red/purple color of your hibiscus extract. Anthocyanins are polyphenols with mild astringency and antioxidant properties. They're pH-sensitive: red in acid, blue in base, colorless in between. Your Hibiscus Drop Botanical Drops get their color from anthocyanins. They also contribute a subtle dryness that balances the sweetness.
Common sources: hibiscus extract (anthocyanin-rich)
03 · Where Tannins Live in Your Extract Library
Three of your key extracts are tannin-forward
Gentian Root Extract
Rich in both tannins (structure) and alkaloids (bitterness). This dual contribution is why gentian is the backbone of so many bitters formulas. The tannins give the bitter compounds something to rest on. Without the tannin structure, gentian's bitterness would feel sharp and floating. With it, the bitterness feels grounded.
Wild Cherry Bark Extract
Condensed tannins from the bark provide firm astringency. This is what gives cherry bark its "woody" mouthfeel. Combined with benzaldehyde (cherry aroma) and mild alkaloid bitterness, cherry bark is a structurally complete ingredient. It brings tannins, aldehydes, and alkaloids in one package.
Wormwood Extract
Tannins alongside its famous bitter alkaloids (absinthin). The tannin content varies by species and extraction time. Over-extracted wormwood becomes harshly astringent. Properly extracted, the tannins support the bitterness with dry, clean structure.
04 · Interactions
Tannins as structural foundation
Tannin interactions
Tannins + Alkaloids
The bitters backbone. Alkaloids provide bitterness (taste). Tannins provide astringency (mouthfeel). Together they create the structural foundation of any serious bitters formula. One without the other feels incomplete. This is why gentian root works so well: it carries both.
Tannins + Terpenes
Structure under aroma. The terpenes make people smell the glass. The tannins make the sip feel substantial. This is the difference between a bitters that's just "fragrant" and one that's "fragrant and structurally complete."
Tannins + Phenols
Both provide body, but differently. Phenols are warm and aromatic (you can smell eugenol). Tannins are dry and physical (you feel them, not smell them). Together they fill out the mid-palate and finish completely. Be careful: too much of both creates heaviness.
Tannins + Furanones
Sweet softens dry. Ethyl maltol's perceived sweetness counteracts tannin astringency perceptually. The tannins are still there structurally, but the overall impression is smoother. This is the same principle as adding milk to tea: milk proteins bind tannins and reduce astringency.
05 · Formulation Implications
Tannins are the family people forget until the formula feels wrong
When the spider chart shows Tannins high, the ingredient will add physical presence, dryness, and grip. The drink will feel substantial in the mouth. This is desirable in bitters, in wine-style beverages, and in any drink that needs to feel "serious."
When to add more tannins: a formula has aroma, warmth, bitterness, but it feels watery when you sip it. There's no grip. No finish. Add a tannin-rich extract (gentian root, cherry bark) or increase the extraction time on an existing botanical to pull more tannins.
When to reduce tannins: the drink is puckering, drying, harsh. It leaves your mouth feeling like you chewed on a tea bag. Reduce extraction time on tannin-heavy botanicals. Or counterbalance: add sweetness (sucralose, ethyl maltol) and richness (lactones, VG for body) to soften the astringency without removing it.
Important: tannins are extracted more aggressively in hot water than in cold. A tea-based cold brew (28 hours, cold) pulls less tannin from Black Assam tea than a 5-minute hot brew would. That's a deliberate choice. You get the flavor compounds without the heavy astringency.
06 · Lab Exercise
Feel Tannin Binding in Your Mouth
Bench Exercise · 10 minutes
Three cups. Same tea. Different tannin loads.
What you need: Black tea (Assam or English Breakfast), boiling water, three cups, a timer.
Cup A: 1 tea bag in 200mL hot water, steep 1 minute. Remove bag.
Cup B: 1 tea bag in 200mL hot water, steep 5 minutes. Remove bag.
Cup C: 1 tea bag in 200mL hot water, steep 15 minutes. Remove bag.
Let all three cool to the same temperature. Taste each one.
Cup A (1 min): Light, aromatic, pleasant. Minimal astringency. You're getting caffeine (alkaloid, bitter) and volatile aromatics but few tannins.
Cup B (5 min): More body, more color, moderate astringency. The tannins are present but balanced. This is what most people consider a properly brewed cup.
Cup C (15 min): Dark, intensely astringent, probably unpleasant. Your mouth feels dry and puckered. The tannins have been over-extracted. Same tea. Same water. Different extraction time = radically different tannin level.
This is why extraction time is one of your most powerful variables when working with tannin-rich botanicals. More isn't always more.
07 · Before You Move On
Quick check
Why can't you smell tannins?
What's the physical mechanism of astringency? What happens to your saliva?
A bitters formula formula has great aroma and genuine bitterness but feels watery in the mouth. Which family is likely missing?
Why does a tea-based formula use cold brew instead of hot brew for the Black Assam tea?
Name the three tannin-rich extracts in a library and what each one contributes beyond tannins.