Products that are to be freeze dried must be present in deep frozen form. Freeze drying takes place under vacuum conditions below the "triple point" (6.2 mbar = 4.6 torr). Here, water will only be present in two phases: ice and vapour. By adding energy to the ice it will sublimate (evaporate) directly into the vapor phase. The vapor is condensed immediately on vapor traps to maintain the vacuum.

Water vapor has easier access through any product cell structure than water, penetrating the product mass to evaporate from the surface of the product as in the case in other drying methods. The gentle escape of water vapor in the freeze drying process leaves the product close to its original shape with its taste and color preserved and with no loss of aroma. The vacuum and temperature used during the freeze drying depends on the product, its shape, water content, product structure and composition.

World leading supplier of freeze dryer systems
GEA Niro is the only supplier of the Atlas freeze drying system and equipment utilized by the coffeefood and pharmaceutical industry in the world. GEA Niro designs and delivers complete drying plants for the coffee industry - the leading coffee brands are produced on GEA Niro equipment.

Freeze drying is a superior preservation method for a variety of food products and food ingredients. Atlas freeze dryers set world standards for design, operation and quality. The delivery program includes plant sizes ranging from pilot scale to large industrial batches and continuous plants.

GEA Niro delivers freeze dryers for the:

Products for freeze drying fall into three basic categories:

  • Liquids such as coffee, tea, juices, and other extracts
  • Individual quick frozen (IQF) products. Such as segments of whole fruits, berries, and vegetables as well as shrimps or segments of fish and meat products.
  • Combined products such as soup blocks, rice dishes, baby purees, camping foods, etc.

Freeze drying of liquids is the most complex process. First, the liquids must be treated to achieve optimal solids content and color. The pre-concentrated liquids must be frozen before the actual freeze drying. This is done either slowly on a CAB (Continuous Air Blast) freezer or more quickly on a ROTA freezer. The frozen product is then granulated (milled) to obtain granules of the desired size before loading and weighing on trays before the freeze drying. The IQF products are loaded in frozen form directly by weight or volume on the trays before the freeze drying. Combined products are usually filled into trays with special plastic moulds that can withstand the extreme temperature changes. The product is then deep frozen in the moulds before the freeze drying.