Compound
Sorbitol
The unfermentable sugar alcohol that pears carry in quantity and apples carry only in trace, and the single reason a fully fermented perry keeps a sweetness a fully fermented cider cannot.
Also called Glucitol, D-sorbitol.
- Class
- Sugar alcohols
- Formula
- C6H14O6
- How often it matters
- Present in every cider
What it does in cider
- Passes through fermentation essentially untouched by Saccharomyces, so it survives into the finished drink at the concentration the fruit supplied.
- Tastes sweet at roughly half to two-thirds the intensity of sucrose, which is enough at pear-juice concentrations to leave a technically dry perry tasting off-dry.
- Adds body and a slight viscosity, so perry has a rounder texture than cider of the same alcohol and residual sugar.
- Is the transport sugar of the Rosaceae: pears, and to a lesser degree apples, move carbohydrate around the tree as sorbitol rather than as sucrose, which is why it is present at all.
- Can be metabolised by some lactic acid bacteria, which is one route by which a stored perry loses sweetness and gains acidity without any yeast being involved.
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.
- soft sweetness
- roundness
- cooling
Distinctly less sweet than sucrose weight for weight, but present in pear juice at concentrations high enough that the difference is easily perceptible in a finished perry.
Descriptors it is responsible for
Sensory records that name Sorbitol as a cause. Each states the perception and the mechanism behind it.
- Ripe pear — Full, soft, honeyed pear character from fruit at or just past maturity, heavier than fresh pear and lower in green notes.
- Tinned pear — The syrupy, slightly flat pear character of canned fruit, from heat-degraded pear esters over residual sweetness.
- Bletted pear — Deep, faintly winey overripe pear character from fruit softened past ripeness, met in traditional perry and in medlar-like notes.
- Cooked pear — Soft, sweet, heat-treated pear character, with the decadienoate top note stripped and a lactone-like weight left behind.
The structure it moves
| Dimension | What it is |
|---|---|
| Sweetness | How sweet the drink tastes, which is not the same as how much sugar it contains. |
| Body | How much weight and viscosity the drink has in the mouth. |
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 sorbitol. 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.
Sorbitol10.0–25.0 g/L
context not recorded · Various journals and institute reports
Pear juice. The range across perry pear cultivars is wide and seasonal variation is real, so a figure for one cultivar in one year should not be read as a property of pears in general. What is consistent is that the figure is an order of magnitude above the apple one.
Sorbitol2.0–8.0 g/L
context not recorded · Various journals and institute reports
Apple juice, for comparison. Enough to make a small contribution to body in cider and not enough to register as sweetness against the acid alongside it.
Sorbitol6.5–6.6 g/L
Villaviciosa, Asturias, Spain, 2001–2002 · 4 samples · HPLC on finished cider · Suárez Valles, Pando Bedriñana, Fernández Tascón, Querol Simón and Rodríguez Madrera, Food Microbiology 24(1):25–31
Apple, not pear. Sorbitol is normally discussed as the thing that separates perry from cider, and it does — perry pear juice carries several times this — but apples carry some too, it survives fermentation untouched, and roughly six and a half grams of it are still in the glass of a dry Asturian cider. The two harvests differed by a tenth of a gram, which is as stable as anything in this table.
A sugar alcohol abundant in pears and largely unfermentable, which is why perry keeps a sweetness cider does not. Measured in grams per litre.
What forms it
Processes that put this compound into the drink, or increase how much of it is there.
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.
Low acidity
A cider without enough acid to give it definition, tasting soft, heavy and dull — and sitting at a pH that leaves it exposed to spoilage organisms.
Lactic off-flavours
Sauerkraut, sour milk, silage or cheesy notes from lactic acid bacteria working on sugars and other substrates rather than on malic acid alone.
Unwanted refermentation
Fermentation restarting in a sealed container, generating carbon dioxide that was not planned for and pressure that a bottle may not withstand.
Starch haze
A persistent haze caused by starch carried in from under-ripe fruit, which has not yet been converted to sugar and stays suspended in the cider.
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.
Framboise
A raspberry-and-rotten-fruit character with sulphurous overtones, produced by *Zymomonas mobilis* in sweet ciders that still contain sugar.
Organisms that produce it
Which organism is responsible usually decides whether the compound is a feature or a symptom.
Saccharomyces cerevisiae
The yeast that finishes essentially every cider, whether it arrives in a sachet or from the fruit, the press and the vessel.
Lactobacillus collinoides
A lactic acid bacterium first described from cider, and the organism most closely associated with acrolein bitterness through its conversion of glycerol.
Oenococcus oeni
The acid-tolerant lactic acid bacterium that carries out most deliberate malolactic fermentation, converting malic acid to lactic acid after the yeast has finished.
Described in full
- Layout
- Four rows — sugars, acid, tannin and finish — with a cider column and a perry column side by side.
- Sugars
- Apple juice carries glucose, fructose and sucrose, all fermentable. Pear juice carries the same three plus sorbitol, a sugar alcohol that tastes sweet and that Saccharomyces cannot ferment.
- Acid
- Apple acidity is essentially malic acid alone. Pears carry citric acid as well, which a single total-acid figure does not distinguish — so two juices with the same titratable acidity can taste different.
- Tannin
- Both carry condensed tannin, but perry pear tannin is typically more astringent and less bitter than apple tannin at the same measured level. A perry pear classified as bittersweet does not taste like a bittersweet apple.
- Finish
- A fully fermented cider is dry unless sugar is added back or fermentation is arrested. A fully fermented perry can still taste distinctly sweet, because the sorbitol survives untouched.
- Why that matters for stability
- Sweetness from sorbitol carries no refermentation risk: there is nothing there for yeast to eat. Sweetness from back-sweetened sugar carries a real one, and needs stabilisation, filtration or pasteurisation.
- What is the same
- The process. Milling, pressing, fermentation, maturation and packaging are the same operations, which is why perry is made in cider cellars and rarely in dedicated ones.
About Sorbitol
Most plants move carbohydrate around themselves as sucrose. The Rosaceae — the family that includes apples and pears — largely use sorbitol instead, a six-carbon sugar alcohol made by reducing glucose. Both fruits therefore contain it, but pears contain far more, and that quantitative difference is the most consequential single fact in the chemistry of perry. A pear juice arriving at the fermenter carries a substantial fraction of its total sweetness in a form that yeast will not touch.
Saccharomyces cerevisiae has no functional route to ferment sorbitol under cider conditions. It ferments the glucose, the fructose and the sucrose, and it leaves the sorbitol exactly where it found it. So a perry can be genuinely dry by every fermentation measure — no fermentable sugar left, gravity below 1.000, alcohol at its theoretical maximum — and still taste noticeably sweet in the glass, because several grams per litre of sweet-tasting material never entered the ferment at all. Cider has no equivalent. An apple juice fermented to dryness tastes dry, and any sweetness in it is either sugar the maker left there deliberately or aroma being misread as sweetness.
This explains a good deal of how perry is described and made. The characteristic softness and roundness of perry, often attributed to lower acidity, is substantially sorbitol; so is the impression that perry ages into something gentler than cider does. It also explains why the sweetness of a perry is hard to control: unlike residual sugar, which a maker sets by arresting a ferment or by back-sweetening, sorbitol is fixed by the fruit and by the blend, and the only lever is cultivar choice.
There are two footnotes worth stating plainly. The first is microbiological: certain lactic acid bacteria can use sorbitol, so a perry that has spent a long time in a warm cellar with an active bacterial population can lose sweetness and pick up acidity and other lactic products, which is a slow change with no visible fermentation to signal it. The second is physiological: sorbitol is absorbed slowly and incompletely, and in quantity has a mild laxative effect. That is a straightforward property of the molecule, it is well documented, and it is the factual basis of a reputation perry has carried for several centuries.
Related compounds
Compounds it is formed from, converted into, confused with, or routinely met alongside.
Sugars
Fructose
The dominant sugar of apple juice and the sweetest of the common sugars, which is why apple juice tastes sweeter than its total sugar figure implies and why a stuck ferment leaves sweetness behind.
Sugars
Glucose
The sugar yeast takes first and the smallest of the three in apple juice, which is why the last sugar left in a slow ferment is almost never glucose.
Acids
Citric acid
A minor acid in apples and a much more significant one in pears, whose metabolism by lactic bacteria is the reason perry gains more butter and more vinegar from malolactic fermentation than cider does.
Alcohols
Glycerol
A syrupy three-carbon alcohol yeast produces as a side reaction of fermentation, which adds weight to a dry cider and is the raw material for one of its more obscure faults.
Acids
Lactic acid
The softer acid that replaces malic when malolactic fermentation runs, halving the acid a cider carries and changing its texture as much as its sharpness.
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.
- Which yeast ferments cider — Saccharomyces cerevisiae finishes almost every cider fermentation, whether it was pitched or arrived from the press house. In a spontaneous ferment it is not the first organism present, only the one that survives the alcohol it makes.
- Which sugar is most of the sugar in apple juice — Fructose, by a long way. Apple juice carries roughly twice as much fructose as glucose, with a smaller amount of sucrose, and fructose is the sweetest of the three on the tongue.
- Why does cider contain lactic acid — Because malolactic bacteria converted the malic acid into it. Malic acid has two acid groups and lactic acid has one, so roughly half the titratable acidity disappears and the cider tastes softer.
- Which bacterium carries out malolactic fermentation in cider — Oenococcus oeni, in cider as in wine. Genome studies find that the cider strains are genetically distinguishable from the wine ones and that the strain most basal to the whole species was isolated from cider.
- When are cider apples harvested — In the northern hemisphere the cider harvest runs from about September to November, with late bittersweets such as Dabinett and Vilberie coming in last. Cider fruit is generally picked riper than dessert fruit, and often gathered from the ground.
- Does a sweeter cider have more calories
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.
Research on pear juice composition and sorbitol in perry
Various journals and institute reports · peer-reviewed literature · registered as competent for this subject
The evidence base for the single most important chemical difference between cider and perry: pears carry substantial sorbitol, which yeast does not ferment, so a fully fermented perry retains sweetness a fully fermented cider cannot.
Perry Pears
L. C. Luckwill and A. Pollard (eds), published for the National Fruit and Cider Institute by the University of Bristol, 1963 · reference work · bibliographic record verified, not opened 2026-08-25 · covers 1963
Bibliographic record verified on 2026-08-25 against Open Library, which records the work as Luckwill, 1963, published for the National Fruit and Cider Institute by the University of Bristol. The catalogue entry names Luckwill alone where the standard citation names Luckwill and Pollard as joint editors; CiderHQ keeps both names and records the discrepancy rather than silently following one catalogue. This is the foundational descriptive work on English perry pears and the ancestor of most later variety lists. No copy was opened: it is sixty years old, out of print, and held in research libraries rather than in open digital collections.
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.
National Perry Pear Centre, Hartpury · specialist organisation · passage verified 2026-08-24
Read on 2026-08-24 — and the address CiderHQ had registered, perrypears.co.uk, is no longer the Centre at all. It fails the TLS handshake over https, and over plain http it resolves to a Sedo domain-parking page: an earlier pass in this sprint recorded it as retrieved on the strength of an HTTP 200, which was wrong, and the correction is the point. The Centre publishes at nationalperrypearcentre.org.uk. It is the closest thing British perry has to an identity authority: it holds at least two examples of most known varieties, states that the DNA of most of them has been determined and is used as an aid to identification, and publishes a variety register with synonym lists. Its 121-variety register is transcribed into the perry pear records, including the nineteen names it shows being claimed by more than one variety.