Step 1. Blending
The character of coffee beans varies naturally from region to region, season to season and variety to variety. Arabica beans produce a rich, aromatic flavour, while Robusta coffee has a more intense flavour with more body. There is great skill involved in tasting samples of the various beans and selecting the right blend to produce a high-quality, distinctive soluble coffee.
Step 2. Roasting
The flavour and aroma of coffee beans are brought to life by the roasting process. Temperature and time are carefully controlled to develop the coffee's flavour to the full. In general, a light roast gives a mild taste, a medium roast produces a well-rounded, rich flavour and aroma, and a high roast gives a strong, distinctive flavour.
“There is great skill involved in tasting samples of the various beans and selecting the right blend.”
Step 3. Grinding
The roasted coffee beans are then ground into a coarse powder. This is the same technique that’s used for ‘Roast & Ground’ coffee which you might buy in your local supermarket or coffee shop.
Step 4. Extraction
The roast and ground coffee is put into a series of extraction cells. These do the same job as a domestic coffee percolator or filter coffee maker: extracting the coffee flavour from the coffee grounds into hot water. This happens using controlled pressure and temperature conditions which makes the extraction process very efficient.
Step 5. Drying
Soluble coffee is produced by drying the liquor in one of two ways.
In spray-drying, the liquor is sprayed into a stream of hot air at the top of a tall cylindrical tower. As the droplets fall, they dry, falling to the bottom of the cylinder as a fine powder.
In freeze-drying, the liquor is frozen to about -40°C to form a thin layer. This is broken into tiny pieces, and then subjected to a vacuum. The vacuum lowers the boiling point of the water sufficiently so that it evaporates even at these very low temperatures, helping to preserve the coffee flavour, and leaving behind the solid soluble coffee.
Spray-drying is used for most soluble coffees, whereas freeze-drying is used for more expensive, higher quality coffees.
“We capture the beautiful aromatics which are released during the grinding process”
Step 6. Agglomeration
Soluble coffee granules are produced from the powder produced by spray-drying through a process called agglomeration. The powder is wetted slightly so that the particles stick together and the resulting granules are sieved so that only particles of the same size are filled into jars.
Step 7. Aromatisation
In the NESCAFÉ range, we capture the beautiful aromatics which are released during the grinding process.
Step 8. Filling
The soluble coffee powder or granules are filled into glass jars or sachets. Filling is carried out in an inert gas atmosphere, to prevent any deterioration of the flavour or aroma of the coffee during storage.
Step 9. Decaffeination
Caffeine is a mild stimulant* which occurs naturally in coffee and a number of other plants, such as tea. While this property of coffee is often desirable, many people prefer the caffeine to be removed.
This is done at the green bean stage, before the beans are roasted. There are three main methods in use today, all of which use the same first step: the beans are treated with steam to make them porous, which allows the caffeine to be removed.
The oldest method used an organic solvent to dissolve out all of the caffeine. More recently, a process using carbon dioxide under high pressure was developed. However, decaffeinated NESCAFÉ coffees in the UK have always used a process which uses water to dissolve the caffeine. In this process, the coffee beans are steeped for a time in hot water, which dissolves the caffeine and some of the flavour compounds. This liquid is then passed through activated carbon, which removes the caffeine. The liquid (now minus most of the caffeine) is then re-integrated with the coffee beans to put back the flavour compounds which were removed along with the caffeine. The beans are then dried, ready for roasting in the normal way.
*British Coffee Association, 2016