Compound
Total phenolics
The single number used to summarise everything phenolic in a juice, useful for comparing fruit and misleading whenever it is used to predict how a cider will taste.
Also called Total polyphenols, Gallic acid equivalents.
- Class
- Phenolics
- Formula
- Not a single molecule — see below
- How often it matters
- Central to how cider behaves
What it does in cider
- Aggregates procyanidins, hydroxycinnamic acids, dihydrochalcones and flavonols into one figure, measured as reducing capacity rather than by identification.
- Separates cider fruit from dessert fruit clearly and reliably, which is what it is genuinely good for.
- Predicts oxidative stability reasonably well, since all phenolics contribute to the pool of oxidisable material.
- Does not predict bitterness or astringency, because it says nothing about the chain-length distribution that decides the split between them.
How it is perceived
What the compound registers as, and at roughly what concentration. Perception is not a property of the molecule alone: sugar, tannin and carbonation all change where a threshold falls.
- structure
- grip
- bitterness
No threshold can be attached to the aggregate figure. Two juices with the same total phenolics can differ completely in perceived bitterness and astringency depending on how the total is composed.
Descriptors it is responsible for
Sensory records that name Total phenolics as a cause. Each states the perception and the mechanism behind it.
- Dessert apple — The bright, aromatic, low-tannin fruit character of eating apples, dominant in eastern counties and most modern mainstream cider.
- Medicinal — A hospital-antiseptic note from volatile phenols, or from chlorophenols formed by chlorine contacting phenolic material.
- Sherry — A nutty, oxidised, faintly volatile character from acetaldehyde and sotolon in long-air-exposed cider.
- Walnut — A dry, slightly bitter nut note from advanced phenolic oxidation, characteristic of long-matured tannic cider.
- Dried apple — Concentrated, leathery apple character from moderate oxidation, sitting between fresh fruit and full oxidative development.
- Dried fruit — Raisin and sultana character from long oxidative ageing, most often met in concentrated and fortified styles.
- Hazelnut — A lighter, sweeter nut note from early oxidative development and from lees contact.
- Leather — A dry, tanned-hide note from low levels of volatile phenols over well-polymerised tannin.
- Maderised — Heat-and-air damage together: cooked, browned, flat character from cider stored warm in the presence of oxygen.
- Metallic — A blood-and-tin taste from dissolved iron or copper, which also catalyses oxidation.
- Straw — A dry, dusty, cereal-like note from advanced degradation of green volatiles in aged cider.
- Acrid smoke — Harsh, ashy smoke from atmospheric smoke absorbed by the fruit, chemically distinct from microbial smokiness.
- Apple core — A faintly bitter, faintly almond-like note from crushed pips and core tissue passing through the mill with the flesh.
- Cedar — A dry, resinous, pencil-shaving wood note from oak volatile phenols with tannin, distinct from sweet oak character.
- Cherry — Dark stone-and-berry character combining benzaldehyde with heavier ethyl esters, met in aged tannic cider.
- Dried apricot — Concentrated stone fruit with an oxidative edge, from lactones developing alongside acetaldehyde and phenolic oxidation.
- Forest floor — Damp leaf, soil and fungal character in aged cider, from the combination of oxidised phenolics with low-level fungal volatiles.
- Plastic — A synthetic, hot-plastic or crayon note from packaging materials, hose or liner contact.
- Violet — A powdery floral note from β-ionone, formed by degradation of carotenoids carried in from the fruit.
The structure it moves
| Dimension | What it is |
|---|---|
| Tannin | The phenolic material that gives cider structure, grip and ageing capacity. |
| Bitterness | A taste sensed at the back of the tongue, distinct from the drying grip of astringency. |
| Astringency | The drying, rough sensation left after swallowing. |
| Phenolic character | Smoky, spicy, leathery or medicinal aromas that sit apart from fruit. |
Measured figures
Shown as they were measured, with the context each was taken in. They are not averaged: a concentration recorded in one country's fruit in one decade is not a constant.
3 separate analyses of total phenolics. They are shown as they were measured, in their own contexts, and are not averaged — the same fruit grown somewhere else can genuinely give a different number.
Total phenolics2000.0–6000.0 mg/L
context not recorded · Folin–Ciocalteu, gallic acid equivalents · INRAE
Bittersweet cider apple juice. The assay measures reducing capacity, not phenolic identity, so this figure describes how much oxidisable phenolic material is present and not how the cider will taste. Extraction conditions move it substantially: the same fruit milled finely and macerated gives a higher figure than the same fruit pressed immediately.
Total phenolics200.0–800.0 mg/L
context not recorded · Folin–Ciocalteu, gallic acid equivalents · INRAE
Dessert and culinary apple juice, given for contrast. The gap between this band and the bittersweet band is the clearest analytical statement of what makes a cider apple a cider apple.
Total phenolics1.1 g/L
Ithaca, New York, United States, 2016 · Folin–Ciocalteu, reported as gallic acid equivalents · Song, Gibney, Cheng, Liu and Peck, Frontiers in Microbiology 11:1264
A blend of culinary and European cider apples pressed rack-and-cloth. Folin–Ciocalteu counts anything that will reduce the reagent, including ascorbate and some sugars, so a gallic acid equivalent is an index of phenolic load rather than a count of phenolic molecules — which is why it cannot be set against a thiolysis figure for the same juice.
All phenolic compounds together, usually reported as gallic acid equivalents. Measured in milligrams per litre.
What forms it
Processes that put this compound into the drink, or increase how much of it is there.
Milling
Reducing whole fruit to a pulp so that the press has cell walls it can drain, rather than intact apples it can only bruise.
Maceration
Holding milled pomace before pressing so that phenolics, aroma precursors and pectin have time to move out of the solid tissue and into the juice.
Pomace conditioning
Letting milled pomace stand before it goes to the press so that it drains better, presses faster and gives more juice.
Blending
Combining separate lots of cider or perry into one, which in cider is the historically normal way of making the drink rather than a remedy applied when single lots disappoint.
Tannin balancing
Setting the phenolic structure of a blend, which means handling bitterness and astringency separately because they are different perceptions produced by different sizes of the same molecules.
What removes or limits it
Processes that reduce it, hold it below a threshold, or stop it forming in the first place.
Fining
Adding a reactive agent that binds a target colloid and carries it to the bottom, chosen according to whether the problem is tannin, protein or a phenolic taste fault.
Juice oxidation
The enzymic browning that begins the moment apple juice meets air, which some traditions deliberately allow and others suppress.
Filtration
Passing cider through a porous medium to reach a stated visual brightness, at a real cost in colloidal material, body and aroma.
Oxidative maturation
Ageing a cider with a deliberate, measured oxygen supply so that tannins polymerise and soften and an aldehydic character develops on purpose, which is not the same thing as the oxidation fault.
Faults it is implicated in
Being implicated is not the same as being a fault. Several of the compounds on this site are ordinary constituents of a sound cider and define a named fault only above a concentration.
Excessive bitterness
Bitterness that dominates the palate rather than supporting it, usually from a blend weighted too heavily towards high-tannin fruit or extracted too hard.
Excessive astringency
A drying, roughening, mouth-puckering sensation that outstays its welcome, produced by larger phenolic polymers precipitating salivary proteins.
Thin body
A cider with no weight or texture in the mouth, most often from over-watered pomace, low-gravity juice or a blend with nothing to give it substance.
Oxidation
The cumulative effect of oxygen on finished cider: fruit aroma flattens, colour deepens towards amber, and a bruised-apple or sherry-like character replaces the fresh one.
Enzymatic browning
The rapid darkening of milled fruit and fresh juice as polyphenol oxidase converts phenolics to quinones, taking colour and some tannin structure with it.
Gushing
Cider that erupts from the bottle on opening, either because it is over-pressurised or because something in it is nucleating the dissolved gas violently.
Mould taint
Musty, earthy, cellar-damp or rotten-fruit character carried in from mouldy fruit or from mouldy equipment, and a marker that the patulin question needs asking.
Acrolein bitterness
An intense, lingering bitterness quite unlike tannin, produced when lactic acid bacteria convert glycerol to acrolein and the acrolein reacts with the cider’s phenolics.
Excessive sediment
More deposit in the bottle or vessel than the presentation intends, ranging from a normal conditioning yeast layer to a loose sludge that clouds every pour.
Flat and lifeless
A cider with nothing obviously wrong and nothing to say: aroma faded, acidity dulled, finish short — usually the cumulative result of over-processing or slow oxidation.
Plastic and packaging taint
Plastic, rubber, adhesive or chemical notes picked up from unsuitable containers, liners, hoses, gaskets or cleaning residues.
Protein haze
A fine haze that forms as protein and tannin combine into insoluble complexes, often appearing in a cider that had already been clear.
Colour loss
A cider left noticeably paler than it should be, usually because fining, filtration or sulphite has removed the phenolic material that gave it colour.
Metal haze
A haze or dark cast caused by dissolved iron or copper picked up from equipment, forming insoluble complexes with phosphate or with the cider’s phenolics.
Metallic taint
A metallic, inky or blood-like taste from dissolved iron, copper or zinc picked up from equipment, usually accompanied by accelerated oxidation.
Pinking
An unexpected pink or salmon tint developing in a pale cider or perry, associated with oxidation of colourless phenolic precursors.
Described in full
- The upper scale
- Five steps — negligible, light, moderate, firm and heavy — matching the tannin scale used everywhere on the site. Each step carries a countable number of marks, one to five, so the level can be read without relying on colour.
- Negligible and light
- Dessert and culinary fruit. There is phenolic material present, but not enough to give grip, and a cider made from it alone tastes thin however well it is fermented.
- Moderate to heavy
- The range bittersweet and bittersharp cider apples occupy. This is the material that gives a traditional cider body, a finish and the capacity to improve with age.
- The lower panel: chain length
- Cider tannin is condensed tannin — procyanidins built by linking catechin and epicatechin units. The horizontal axis runs from short chains, dimers and trimers, to long polymers.
- Short chains taste bitter
- The bitterness band is thick at the short-chain end and tapers away. Small oligomers reach bitter receptors on the tongue; it is a taste, sensed at the back of the mouth.
- Long chains dry the mouth
- The astringency band is thin at the short-chain end and thickest at the long. Long polymers precipitate salivary proteins, stripping the lubricating film — a mechanical sensation, not a taste, and it builds across sips rather than fading.
- Why the total figure misleads
- Two juices with identical total tannin can taste entirely different if one carries mostly short chains and the other mostly long. Chain length, not total, decides which sensation dominates — and this is the axis the Long Ashton scheme does not measure.
- What maturation does
- Chains polymerise and eventually precipitate with time. A young cider that is aggressively bitter often becomes softer and more drying, then quieter, as its tannins move rightwards along this axis and then out of solution.
About Total phenolics
Total phenolics is a convenience. The Folin–Ciocalteu reagent is reduced by phenolic hydroxyl groups and the resulting colour is read against a gallic acid standard, giving one number for a mixture of hundreds of compounds. It is quick, cheap, reproducible and available to any laboratory, which is why it is the phenolic figure most widely published for cider fruit.
It does two jobs well. It distinguishes cider fruit from dessert fruit unambiguously — the bands barely overlap — and it gives a reasonable indication of how much oxidisable material a juice contains, and therefore how it will behave when exposed to air. For a maker deciding whether a load of fruit is worth pressing separately, it answers the question.
It fails at the question people most want to ask it. Bitterness comes disproportionately from small oligomers and astringency from long polymers, and a Folin reading is blind to the difference; it is also blind to the difference between a procyanidin and a hydroxycinnamic acid, which behave nothing alike on the palate. This is the same limitation the Long Ashton tannin figure carries, stated in modern units. A total-phenolics number tells a reader how much phenolic material is present, and the sensory questions require either a chain-length analysis or a trained panel.
Related compounds
Compounds it is formed from, converted into, confused with, or routinely met alongside.
Phenolics
Procyanidins
The condensed tannins of cider fruit, whose chain length — not their quantity — decides whether the mouth registers bitterness or astringency.
Phenolics
Chlorogenic acid
The most abundant single phenolic in apple juice, the preferred substrate of the enzyme that browns it, and the precursor of one of the volatile phenols behind farmyard character.
Phenolics
Epicatechin
The flavan-3-ol that apple procyanidins are almost entirely built from, and the most bitter of the phenolic monomers a cider contains.
Phenolics
Phloridzin
A dihydrochalcone found in apple and essentially nowhere else, which makes it both a contributor to bitterness and the standard chemical proof that a juice is apple juice.
Phenolics
Gallic acid
A minor phenolic acid in apple that matters chiefly as the reference standard every total-phenolics figure in cider is expressed against, and as a marker of oak contact.
Phenolics
Quercetin glycosides
The yellow flavonols of apple skin, made in response to sunlight, which contribute a fine astringency and reach the juice only in proportion to how much skin was pressed.
What people ask next
Questions readers ask about the things this page mentions. Each one goes to the section that answers it rather than to a page written to receive the question.
- What are procyanidins in cider — They are the condensed tannins of apples: chains of catechin-type units whose length decides how much of the phenolic load reads as bitterness and how much as astringency. Two ciders with identical total tannin can taste nothing alike.
- What is oxidation in cider
- Is cider vegan — Cider itself is a plant product, but some producers clarify it with animal-derived finings such as gelatine, isinglass or chitosan. Vegan status therefore depends on the fining regime, which is why some ciders are certified and others are not.
- How are apples milled for cider
- How do you blend cider
- Why does my cider dry my mouth out — Astringency is tannin binding the proteins in saliva, which is felt as roughness rather than tasted. Too much comes from heavy pressing, long maceration, or fruit far higher in tannin than the blend can carry.
Where to go next
- All compounds — Grouped by what the fruit brings and what the ferment makes of it.
- Sensory — Every descriptor, with the compound or process that causes it.
- Microbiology — The organisms whose metabolism most of this chemistry belongs to.
Sources
What this page rests on. Where a source is marked as registered rather than read, CiderHQ is recording that the body is authoritative on the subject without claiming to have worked through the document itself. See our evidence policy for what each state means.
Institut national de recherche pour l’agriculture, l’alimentation et l’environnement (INRAE)
INRAE · research institute · retrieved 2026-08-24
French national agricultural research. Its Angers programme produced much of the published work on apple procyanidin chain length and on the relationship between polymer size, bitterness and astringency.
Long Ashton Research Station cider fruit analyses
National Fruit and Cider Institute / University of Bristol · research institute · registered as competent for this subject · covers 1903–2003
The foundational body of cider-fruit science in English. Long Ashton produced the acid-and-tannin classification that divides cider apples into sweet, sharp, bittersweet and bittersharp, and analysed hundreds of cultivars grown at its Somerset site. Its figures are historic measurements of specific fruit at a specific place, not universal constants — a distinction CiderHQ preserves in every measurement record that cites it.
Peer-reviewed literature on apple phenolics and cider sensory perception
Various journals · peer-reviewed literature · registered as competent for this subject
Registered as a class rather than as one paper, because the mechanisms CiderHQ describes — tannin chain length driving the split between bitterness and astringency, salivary protein precipitation, enzymatic browning — are established across many studies rather than resting on any single one. Individual papers are cited where a specific number is quoted.
The Science of Cidermaking and associated technical writing
Andrew Lea · reference work · passage verified 2026-08-24
Written by a food chemist who worked at Long Ashton on apple phenolics. Unusual among specialist cider writing in that it is primary-research-adjacent: the author is describing work he did, and cites the literature. This is why it is registered at tier 1 for chemistry while a general cider book is not.