Compound
Ethyl carbamate
A trace contaminant formed when urea reacts with ethanol, present at low levels in fermented drinks and a genuine concern in apple spirits rather than in cider.
Also called Urethane.
- Class
- Nitrogen compounds
- Formula
- C3H7NO2
- How often it matters
- Occasional
What it does in cider
- Forms spontaneously when urea, excreted by yeast metabolising arginine, reacts with ethanol.
- Accumulates faster with heat and with time, so storage conditions affect the final concentration.
- Concentrates during distillation, which is why the compound is regulated and monitored in spirits including apple brandies far more closely than in the drinks they are distilled from.
- Is minimised by avoiding urea-based nutrients, by not over-feeding nitrogen, and by keeping finished product cool.
What forms it
Processes that put this compound into the drink, or increase how much of it is there.
Inoculated fermentation
Starting a ferment by pitching a chosen yeast culture so that one known strain, rather than the fruit’s resident population, does the work.
Nutrient addition
Supplementing a characteristically nitrogen-poor juice so that yeast can complete fermentation without producing sulphide or stalling.
Cellar storage
Holding packaged cider in conditions that let it change slowly and predictably, where stability of temperature matters more than the temperature itself.
Fortification
Adding distilled spirit to juice or cider so that fermentation cannot proceed, the classic route to pommeau and a step that generally takes the product outside the legal category of cider.
What removes or limits it
Processes that reduce it, hold it below a threshold, or stop it forming in the first place.
Cold chain
Keeping an unpasteurised, unfiltered or back-sweetened cider refrigerated from the packaging hall to the point of sale, because refrigeration is the only thing holding it stable.
Yeast selection
Choosing which cultured strain to pitch, on the basis of the temperature, nitrogen, alcohol and aroma behaviour that separates one commercial yeast from another.
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.
Lactiplantibacillus plantarum
A versatile lactic acid bacterium, renamed out of *Lactobacillus* in 2020, capable of malolactic conversion and of a range of faults depending on conditions.
About Ethyl carbamate
Yeast metabolising arginine produces urea, and some of it leaves the cell. Urea and ethanol react slowly and spontaneously to give ethyl carbamate, so every fermented drink contains a trace of it, and the amount rises with temperature and with time in store. Lactic acid bacteria contribute by a second route, breaking down arginine to citrulline, which reacts similarly.
In cider the concentrations involved are low and the compound is not a practical concern at the point of drinking. Where it becomes one is distillation, because the precursors and the compound itself carry into the spirit and are concentrated there. Apple brandies are made from cider, so the cidermaker supplying a still has an interest in the chemistry that the cidermaker supplying a bottle shop does not.
The practical measures are the same ones good fermentation management already implies: do not use urea as a fermentation nutrient, do not over-supply nitrogen, prefer yeast strains that do not excrete urea freely, and keep finished product cool. It is a compound to design out rather than to test for.
Related compounds
Compounds it is formed from, converted into, confused with, or routinely met alongside.
Nitrogen compounds
Ammonium nitrogen
The nitrogen form yeast takes up fastest and the one most nutrient additions supply, useful for rescuing a ferment and a poor substitute for a properly balanced juice.
Nitrogen compounds
Amino acids
The largest usable nitrogen fraction in apple juice, and the raw material from which yeast builds both its own protein and most of the aroma compounds a cider carries.
Alcohols
Ethanol
The alcohol yeast makes from fruit sugar, which converts a perishable juice into a keepable drink and carries most of its aroma to the nose.
Nitrogen compounds
Yeast-assimilable nitrogen
The nitrogen a yeast can actually use, which apple juice is chronically short of — the shortage behind both stuck fermentations and rotten-egg aromas, and the shortage keeving deliberately makes worse.
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.
- How many calories are in cider — Roughly 40 to 60 kcal per 100 ml for most ciders, so a UK pint falls somewhere around 200 to 250 kcal. Alcohol contributes about 7 kcal per gram and residual sugar about 4, so both strength and sweetness matter.
- 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.
- What is yan and why does cider juice run short of it — Yeast assimilable nitrogen is the nitrogen yeast can actually use. Apple juice is usually short of it — in one Virginia survey of 108 samples, 94 per cent fell below the level wine practice treats as a minimum — which is why cider ferments stall more readily than wine ferments.
- What yeast should i use for cider — CiderHQ does not recommend brands. The choice is between a neutral, reliable strain that lets the fruit show, an aromatic wine strain that adds its own esters, and no addition at all. Alcohol tolerance, cold tolerance and nitrogen demand are the properties worth comparing.
- Can you make cider from shop bought apple juice — Yes, provided the juice contains no preservative — check for potassium sorbate or benzoate on the label. Pasteurised juice ferments perfectly well once yeast is added, because pasteurisation removes the organisms but not the sugar.
- Does cider need to be refrigerated — Unopened, no — cool and dark is enough for most cider. Unpasteurised, unfiltered cider keeps far better cold, and anything opened should go in the fridge.
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.
European Food Safety Authority scientific opinions
EFSA · regulator · retrieved 2026-08-24
Registered for the food-safety questions cider genuinely raises: patulin in juice from rotten fruit, sulphite sensitivity, and the toxicology behind additive limits.
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.
Hochschule Geisenheim University — beverage technology
Hochschule Geisenheim · university · retrieved 2026-08-24
German beverage-technology research covering apple wine and fruit juice processing, including the enzymology of clarification.