British Coffee Association - Soluble
Soluble

Soluble

Turning green coffee beans into high quality soluble coffee products requires a technical expertise. There is also a great skill involved in tasting samples of the various beans and selecting the right blend to produce a high quality, distinctive soluble coffee.

Coffee plantationWhen the beans have been roasted they are then ground into a coarse powder – this is the same as ‘Roast & Ground’ coffee which you might buy from your local supermarket or coffee shop.

When making coffee that is soluble, the roast and ground is put into a series of extractor cells.

A series of cells are used to produce stronger and stronger coffee, until the coffee consists of a syrupy liquor.

Soluble coffee is produced by drying the liquor in one of two ways:

  • Spray-drying
    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, landing at the bottom as a fine powder.
  • Freeze-drying
    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 hard 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. Freeze-drying is used for the more expensive, higher quality coffees.

Soluble coffee granules are produced from the powders produced by spray-drying by a process called agglomeration. The powder is wetted slightly so that the particles stick together, and then the resulting granules are sieved so that only particles of the same size are selected.

In some products, an oil containing the aroma of freshly ground coffee is captured during the roasting process, and added back to the coffee just before it is put into jars.

The soluble coffee powder or granules are put into glass jars or sachets. The air is extracted immediately before the jars or packs are sealed to keep the coffee fresher for longer.