Laboratory cryogenic spray drying equipment and freeze drying equipment are two different models. The freeze drying technology described below is a freeze drying equipment.
The freeze-drying technique is a technique in which a wet material or a concentrate is frozen to a solid state at a lower temperature (-10 to -50 ° C), and then the water therein is directly sublimated into a gaseous state under vacuum to finally dehydrate the material.
Freeze drying can cause some damage to microbial cells. During the lyophilization process, the cells undergo the effects of freezing and drying, which can lead to changes in the physical conditions of the cell membrane or the structure of the sensitive protein, resulting in a decrease in cell viability.
During lyophilization, the water inside and outside the cell is frozen into ice, and the ice crystals cause damage to the cells. Freeze-drying will cause solute effect, cause cell water to overflow, enzyme protein and inhibition inactivation, membrane permeation of cell membrane, so that intracellular substances and extracellular water-soluble substances exchange bidirectionally in an uncontrolled manner, thereby causing metabolic damage of cells.
In addition, lyophilization also changes the fatty acid on the cell membrane and destroys the integrity of the cell membrane. Adding a certain proportion of lyoprotectant before the material is freeze-dried can greatly reduce the damage of the lyophilized microbial cells, and can also play a good protective role in the preservation process of the microbial agent. Such protective agents include separation and screening of glycerol, amino acids, polyethylene glycols, and sugar-feeding yeasts, and protective agents for the development of microecological preparations.
Freeze-drying technology is a good quality drying method. However, it requires expensive special equipment, long drying time, high energy consumption during drying and high processing cost.
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