There’s a lot to learn – let alone keep in mind – when it comes to the challenging task of freeze-drying food or pharmaceutical products. Our experts have compiled the most relevant information about lyophilization for you here.
Freeze-drying/lyophilization: What you need to know
- Also called lyophilization or sublimation technique
- Drying of foods or pharmaceuticals, for example, in a frozen state
- Transition of water from solid to gaseous state without passing through the liquid phase
- Drying method that is the most gentle to products
- The dried material is called lyophillisate
The products are placed in a device on the temperature plates and are cooled down to below -18 °C by the surface temperature of the plate. As soon as the freezing temperature is reached, the chamber is placed under vacuum. A vacuum of less than 200 mbar is usually required here.
- Primary drying/sublimation:
During this stage of the process, the temperature of the plates is increased. Depending on the product, the temperature may rise to 0 °C to 15 °C here. Due to the very slow heating of the plates, the liquid is removed from the product without liquefying. Primary drying is the most important and at the same time most critical process stage in freeze drying.
- Secondary drying:
During secondary drying, the tightly bound water is finally converted into water vapour by further increasing the temperature to over +50 °C in order to reduce the water content to 0.5 - 3%.
- Qualification of the plate temperature with five measuring points per plate
- Measurement of the plate temperature with testo 190 T3/T4 or testo 191 T3/T4 plus probe holder for freeze-drying
- Steam in Place (SIP):
Subsequent sterilization of the system with superheated steam under specified time and temperature conditions
- DIN EN ISO 13408-1:
Requirements for the development, validation and routine control of aseptic processing for health care products
- DIN EN ISO 13408-3:
Describes all the relevant specifications for freeze-drying
- testo 190/191 system consisting of data loggers, software and multifunction case
- Large measurement data memory for long measurements
- Measuring range -50 to +140 °C for use in freeze-drying and SIP
- Probe holder as an accessory, in conjunction with the flexible probes for the data loggers testo 190 T3/T4 and testo 191 T3/T4, for optimum measurement on the plate
Where do you use freeze-drying processes?
In the food industry:
testo 191 HACCP data logger system
In the pharmaceutical industry:
testo 190 CFR data logger system