Foundational
Instant coffee, explained
Instant coffee is brewed coffee with the water taken out: how the extract is made and dried, what the law lets it contain, and why humidity is what spoils it.
In short
Instant coffee is coffee that has already been brewed. A factory extracts roasted, ground coffee with hot water, concentrates the liquid and removes the water, leaving solids that dissolve again in a cup. Nothing in a jar of plain instant coffee is anything other than coffee, and in the European Union that is a legal requirement.
The two things worth understanding are how the water is taken out, because that is where the kinds of instant coffee differ, and how easily it comes back in.
What the law says instant coffee is
Sourced
European law defines coffee extract, soluble coffee and instant coffee as one thing: the concentrated product obtained by extraction from roasted coffee beans using only water as the medium of extraction, excluding any process of hydrolysis involving the addition of an acid or a base. Apart from insoluble substances that cannot technically be removed and insoluble oils from the coffee, it must contain only the soluble and aromatic constituents of coffee.
The same directive fixes how much of the product must be coffee solids: not less than 95 per cent by weight for the dried product, 70 to 85 per cent for a paste, and 15 to 55 per cent for a liquid extract. Solid and paste extracts may contain nothing but what came from the coffee. That is the definition for the European Union; no equivalent text for other countries was read.
From roasted beans to a jar
Sourced
The sequence as one manufacturer's patent sets it out. The figures in the paragraphs that follow are that patent's, and are given to show the scale, not as a description of every factory.
Roast and grind
The starting point is ordinary roasted and ground coffee. The patent calls the conventional method extraction of roast and ground coffee with water.
Extract under pressure
Hot water is passed through a series of cells packed with coffee, much hotter and at higher pressure than any kitchen brewer.
Strip the aromanot always done
Volatile aromatic compounds are taken off the dilute extract and kept, so that they are not lost in the stages that follow.
Concentrate
Water is removed from the extract until it is several times stronger, which leaves less to take out in the dryer.
Dry
The concentrate is either sprayed into hot air or frozen and dried under vacuum. This is the step that makes the two familiar kinds of instant coffee.
A model of soluble coffee manufacture drawn from one patent's description. It shows the order of the steps; it carries no measurements and real plants vary.
Why it is not just a large cafetière
Sourced
The patent, from a large manufacturer with a priority date of 1965, describes a typical extraction cycle in which water at about 150 to 170 degrees Celsius is introduced under pressure into the first cell, with the extract drawn off where the temperature is about 100 degrees. The extract leaves containing 10 to 20 per cent by weight of soluble coffee solids and is concentrated to between 25 and 60 per cent before drying.
Those temperatures are far above anything used to brew a cup, and they are why the European definition troubles to exclude hydrolysis with added acid or base: the question of how hard the coffee may be worked to get solids out of it is a real one in this industry. The figures are sixty years old and belong to one company's process.
Spray-dried and freeze-dried
Sourced
The characterisation below is from the introduction to a 2026 drying study, which summarises earlier work and whose own experiment was on freeze drying and a newer hybrid, not on spray drying. No tasting comparison of the two was read.
- Spray drying
- The liquid is atomised into fine droplets and dried rapidly with hot air. The study describes it as offering high throughput and low production cost, with high temperatures that can cause major losses of volatile flavour compounds.
- Freeze drying
- The concentrate is frozen, broken into granules and the ice removed as vapour under vacuum. The study describes it as better retaining flavour and aroma, and as consuming more energy. The patent describes grinding the frozen sheet to between 0.25 and 2.0 millimetres before drying.
The thing that spoils it is water in the air
Sourced
Instant coffee is a very dry powder that takes up moisture readily. A 2025 study describes it as typically holding 2 to 4 per cent moisture and cites earlier work putting the point at which it cakes at around 5 to 7 per cent.
The authors took one instant coffee out of its jar, spread it in an open layer and kept it at 20 degrees Celsius at three levels of humidity. At 11 per cent relative humidity it stayed stable for the whole period they observed. At 32 per cent it reached 5.4 per cent moisture within eight days; the powder held up in the short term, and the acidity of the coffee made from it had shifted notably after six months. At 65 per cent, a level the authors say is easily reached in kitchens and cellars, it passed its critical moisture within a week and reached 14 per cent within twenty days, with rapid visible deterioration, slower dissolving and poorer brew quality within three months.
This was one product, fully exposed, which is a harsher test than a jar that is opened and closed. What it supports is the ordinary advice, with a reason attached: keep the lid on, and keep a wet spoon and kettle steam out of the jar.
Caffeine by the spoonful
Sourced
Instant coffee is measured out as powder, and powder is concentrated coffee, so it cannot be compared gram for gram with ground coffee. The one survey with stated amounts found a 2 gram serving of instant coffee delivering from about 38 to about 115 milligrams of caffeine depending on the product.
CoffeeHQ's caffeine estimator uses that spread, 19 to 58 milligrams per gram of powder, for instant coffee. It is a range from one survey, wide because products differ, and the tool presents it as an estimate. Decaffeinated instant coffee falls under both rules described on the decaf page: the European 0.3 per cent of dry matter, and the United States residue limit for methylene chloride, which names decaffeinated soluble coffee extract explicitly.
Making a cup
CoffeeHQ explanation
Common practice, with no study behind it. Adjust by taste.
- Measure the powder, not the water, first. Start from the amount on the jar and change one thing at a time. Strength here is simply powder against water.
- Dissolve in a little hot water before adding the rest. Stirring the powder into a small amount of water first avoids lumps, and matters most when the drink is then topped up with milk or poured over ice.
- For a cold drink, dissolve hot and then chill. Instant coffee dissolves slowly in cold liquid, so dissolve it in a splash of hot water and add cold water, milk or ice afterwards.
Where the evidence on instant coffee runs out
CoffeeHQ explanation
It does not say that instant coffee is worse or better than brewed coffee, and it does not rank freeze-dried above spray-dried on taste, because no tasting comparison was read. It gives no shelf life in months. It does not say which species or grades of coffee go into instant coffee, how much of the world's coffee is drunk this way, or how agglomerated granules are made; no source for any of those was opened. It does not cover mixes with creamer and sugar, which are different products under the law quoted above. And the manufacturing figures are one company's from 1965.
What to do next
- The history of instant coffee — How soluble coffee was developed and adopted, from a history that was checked passage by passage.
- Decaf coffee — The solvent limits and the labelling rule that also apply to decaffeinated instant coffee.
- Caffeine estimator — Estimates a range for a spoonful of instant coffee, by weight of powder.
- Ready-to-drink coffee and concentrates — Liquid extracts are defined by the same directive; this explains how they are kept safe.
- Storing coffee — How instant coffee, beans, ground coffee and capsules each need keeping.