Instant – or soluble – coffee is made from coffee beans that have been roasted and ground. The ground beans are then extracted with hot water to recover the coffee flavour and aroma. The process is similar to using a coffee percolator at home. The coffee extract is then dried in one of two ways:
In spray-drying the coffee extract is sprayed into a stream of hot air at the top of a tall cylindrical tower. As the droplets fall, they dry, becoming a fine powder by the time they reach the bottom. The powder may then be texturised into granules to facilitate dosage and dissolution. The quality of the aroma and flavour are preserved thank to the very fast drying occurring during this process. Spray-drying is the most commonly used drying process.
In freeze-drying, the coffee extract is frozen to about – 40°C and cut into granules. The frozen granules are then dried at low temperature and under vacuum. The quality of the aroma and flavour are protected by the very low temperature and gentle drying conditions.