Freeze Drying (Lyophilization) Process: Fundamentals and Advances in Food Industries

Freeze drying or lyophilization is a type of dehydration process based on removing frozen water by sublimation under very low pressures, approximately vacuum. Freeze drying process is run at low temperatures and results in high quality products. Nowadays this process is a suitable replace for hot air drying because it preserves nutrients and aroma of materials that are freeze dried. Freeze-dried foods have a very high quality, preserved nutrients, good sensory characteristics and a long shelf life. There are many food and pharmaceutical products which can be freeze dried including plants, fruits, many vaccine, proteins, peptides and many drugs. So, freeze drying is very effective and necessary technology in food and pharmaceutical point of view. However like every field of science or industry, the freeze drying has their own challenges. This method is somehow an expensive process. However, freeze drying should not be regarded as a prohibitively expensive process if it gives an added value to the product and when dealing with high-value raw materials. Mainly, freeze drying has 3 stages including pretreatment, freezing and drying. The purpose of this review is to provide some viewpoints on the fundamentals of freeze drying and its application in food industry.

Keywords:

Freeze drying , Sublimation , Pretreatment , Annealing , Food industry