Instant coffee is typically dried through two main methods: spray drying and freeze drying. These processes remove the water content from brewed coffee extract, transforming it into soluble granules or powder.
According to Bassoli (2019), the two operations usually applied for this purpose are spray drying and freeze drying.
The Two Primary Methods for Drying Instant Coffee
Here are the key techniques used to dry brewed coffee extract into instant coffee:
- Spray Drying: This is a widely used, more economical method. The liquid coffee extract is sprayed as a fine mist into a stream of hot air. The water evaporates rapidly, leaving behind dry coffee particles.
- Agglomeration: Spray drying is generally followed by an agglomeration process. This step combines smaller coffee particles into larger clusters. The purpose of agglomeration is to generate larger particles that can better dissolve in the consumer's cup, improving the user experience (Bassoli, 2019).
- Freeze Drying: This method involves freezing the coffee extract and then subjecting it to a vacuum. Under vacuum, the frozen water sublimates directly from solid ice to water vapor, bypassing the liquid state.
- Freeze-drying is a more complex and expensive process but is often preferred for preserving more of the coffee's original flavor and aroma compounds, resulting in a higher-quality product.
Both methods effectively remove moisture, making the coffee stable for storage and allowing it to dissolve quickly when hot water is added.
