To freeze dry a product, it is necessary to bring the product to a frozen form. The coffee concen-trate is removed continuously as frozen flakes from the CAB or ROTA freezer. The pre-broken flakes are led into a granulator (milling) system, where the final shape, size and particle distribution is determined. The granulated product is sieved into three fractions:
- Fines – A small amount of too small particles are recycled via a melting tank into the coffee concentrate tank for further treatment. Thus loss of product is avoided
- Oversize – A small amount of oversize granules are led to a second granulator for further milling. The milled “oversize” fraction is recycled to the sifter – thus no product loss.
- Correct Size Granules are led to the automatic tray filling system for even distribution of the product in the trays before they enter the RAY™ or CONRAD™ freeze dryer. By adjusting the mills and changing the mesh size of the sieve nets it is possible to adjust the granule size and distribution exactly to what the market wants.
The overview of the pretreatment freezing, granulation and sieving of the whole process: