Spray drying | Agglomerated coffee | Freeze drying

We have various blends developed to suit tastes across various countries. We have pure robusta, pure arabica and robusta arabica mixes to ensure taste of coffee on one hand and value for money on the other. We have developed various coffee chicory mixes that afford an unbeatable price to many mix manufacturers across the world.

Spray drying

This method of drying is preferred to freeze drying in some cases because of its cost effectiveness, short drying time, usefulness when dealing with such a heat sensitive product, and the fine, rounded particles it produces.

Spray drying produces spherical particles of size roughly equal to 300 µm with a density of 0.22 g/cm³ (ref 2). To achieve this, nozzle atomisation is used. Various ways of nozzle atomization can be used each having its own advantages and disadvantages. High speed rotating wheels operating at speeds of about 20,000 rpm are able to process up to 60,000 pounds (27 t) of solution per hour (ref 3). The use of spray wheels requires that the drying towers have a wide radius to avoid the atomised droplets collecting onto the drying chamber walls.

Typical spray drying characteristics

	Completed in 5-30 seconds (dependent on factors such as heat, size of particle, and diameter of chamber).
	Moisture content change, In= 75-85 per cent Out = 3-3.5 per cent
	Air temperatures, In = 270 °C Out = 110 °C

Agglomerated coffee

Agglomerated coffee is preferred by many customers on account of its easy dissolution format. Our experience from supplying agglomerated coffee across the world has taught us that physical characteristics like granule size and uniformity are as important in granulated coffee as organoleptics like taste, body and zing.

We are able to prepare excellent quality golden and dark brown agglomerated coffee as required by different markets.

Freeze drying

We are glad to inform that our new Freeze Dried Coffee plant will commence its production from March 2007. The plant is being set-up with the latest machineries having state-of-the-art technology obtained from E & E, Germany.

The basic principle of freeze drying in the process for producing instant coffee is the removal of water by sublimation.

Since the mass production of instant coffee began in post-WW II America, freeze drying has grown in popularity to become a very common method. This is often because although it is frequently more expensive than other methods of drying it generally results in a higher quality product.

The freeze drying process

Agglomerated wet coffee granules are frozen. For instant coffee this is a very important stage. Freezing too fast leads to large ice crystals and a very porous product and can also affect the colour of the coffee granules.

Frozen coffee is placed in the drying chamber, often on metal trays. A vacuum is created within the chamber. The strength of the vacuum is critical in the speed of the drying and therefore the quality of the product. Care must be taken to produce a vacuum of suitable strength.

The drying chamber is warmed, most commonly by radiation but conduction is used some plants and convection has been proposed in some small pilot plants. A possible problem with convection is uneven drying rates within the chamber, which would give an inferior product.

Condensation - the previously frozen water in the coffee granules expands to 107 its volume, the removal of this water vapour from the chamber is vitally important, making the condenser the most critical and expensive components in a freeze drying plant.

The freeze dried granules are removed from the chamber and packaged.

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