Freeze Drying (Lyophilization)

It is a gentle process that preserves the original shape, color, taste and nutritional value of the product.

Freeze drying is an effective method to extend the shelf life and has two important features: 1. There is no air in the environment during the process. 2. Drying takes place at a temperature lower than ambient temperature. Intermediate processes in freeze drying are freezing, concentration, condensation and defrosting stages. This method generally consists of two important steps.

In the first stage, the product is frozen, in the second stage, the ice formed is directly sublimed and the product is dried under reduced pressure (27-133 Pa). In many freeze-drying processes, temperatures of ≤ -10oC and pressures of ≤ 2 mmHg are used.

In the freeze-drying process, the freezing stage, the first and second drying periods are important stages that affect the quality of the freeze-dried product. In the freezing stage, the product to be dried using very low temperature is frozen. In the first drying period, free water in the material to be dried, and in the second drying period, bound water is removed. The advantage of freeze drying over other drying methods is the high quality of the final product. Freeze drying process is a system that prevents the loss of taste, smell and aroma that may occur during the traditional drying process. The aroma and nutritional value of the product is very high. The items in the cell do not rise to the surface and disperse. The dimensions and color of the product remain unchanged and the original form is preserved. In addition, the rehydration ability of the product is very superior and shrinkage is minimal. Very low temperature during the process, low relative humidity, very rapid local water loss reduce non-enzymatic browning, degradation of proteins in the structure of the food and enzymatic reactions compared to other traditional drying methods.