FIG (1): Crystal growth after vacuum-induced nucleation


FIG (2): Scanning electron micrograph; product structure after application of SynchroFreeze during freezing and following freeze-drying. Micrograph by courtesy of IDT Biologika.


[1] Allmendinger, A., et al. (2016). Controlled nucleation during freeze drying using vacuum-induced surface freezing. data base no. 633018,

HOF SynchroFreeze

SynchroFreeze describes a development of HOF for controlled nucleation. The aim of this equipment option is to provide the user with an innovative tool to increase the quality of the pharmaceutical product and simultaneously ensures an efficient operation of the freeze drying systems.

The product-specific test results confirm the high expectations for the SynchroFreeze technology, indeed only limited system modifications are required for an implementation into the existing system.

Conditioning and Freezing Phase

SynchroFreeze is characterized by conditioning phase, followed by cooling and vacuum-induced nucleation during the freezing process. In the conditioning phase, dissolved gases are withdrawn from the liquid product under partial vacuum, in order to prevent from strong gas bubble formation and swelling of the product in the subsequent freezing steps.

The now largely degassed liquid is cooled and the nucleation is triggered by a further pressure drop at the desired freezing point in the lower millibar range (FIG. 1).

Studies on SynchroFreeze are carried out by different development teams.  Application related adjustments of the freezing phase are described within first publications (diagram 1).

In many cases, the targeted application of SynchroFreeze allows the optimization of the product structure (Figure 2) as well as a significant reduction of the drying times. The positive influence of SynchroFreeze on the reconstitution of the lyophilisate is the subject for further studies.

HOF SynchroFreeze - for optimized freeze drying processes 

  • to synchronize the freezing process in the individual vials or product containers
  • to condition the product structure
  • to improve the product homogeneity
  • to reduce the required drying times
  • to increase the performance and reduce the energy consumption

"With the implementation of the HOF SynchroFreeze, especially the performance of the freeze drying systems and their energy efficiency could be further improved. It will be now exciting to observe the industrial use of the future-oriented process technology. We enjoy meeting these new challenges and tasks."

Gerhard Schilder - Business Development Manager