The cooling and freeze-drying of cultures for dairy production
The importance of temperature control
Temperature control is vital within the cold chain for cultures. The cold chain is a carefully planned sequence of controlled temperature and storage conditions designed to ensure that the cultures remain fresh and active. This process begins with the storage of the cultures at the production site of Sacco, our Italian partner with whom we collaborate to offer unique combinations of cultures. The cold chain concludes with storage at our customer’s facility. Maintaining the correct temperature throughout the entire cold chain (transport and storage) is crucial to ensuring that the cultures retain their optimal functionality.
The difference between freeze-dried and frozen cultures
There are two different methods for preserving cultures: freeze-dried and frozen cultures. We explain the difference between these two methods.
Freeze-dried cultures
Freeze-dried cultures are created by removing nearly all moisture from the cultures, a process known as lyophilisation. This results in dry, small granules. Cultures that can be added directly to milk without additional treatment and are produced using this method are called DSL cultures, which stands for Direct Set Lyophilized.
During storage, freeze dried cultures retain their original biological activity. When added to milk, they are reactivated. The cultures begin to grow, kickstarting the fermentation process.
Freeze dried cultures are less sensitive to temperature fluctuations but must be stored at a temperature of at least -18°C. If the cold chain is interrupted for several days, this can impact the activity of the culture. In such cases, the culture may work more slowly, requiring additional fermentation time to acidify the product to the desired pH level.
Frozen cultures
Frozen cultures are immediately frozen after production to -40°C or lower. Cultures that can be added directly to milk without additional treatment and are produced using this method are called DSF cultures, which stands for Direct Set Frozen. Due to this process, frozen cultures require a constant temperature of -40°C or lower.
To store cultures at -40°C or lower, specialised freezing equipment with a temperature range of -40°C or lower is required. In2Food supplies freeze dried cultures, eliminating the need for our customers to invest in specific freezing equipment. However, in consultation with our customers, we can explore the possibilities of providing frozen cultures.
Storage and transport of freeze dried cultures by In2Food
After In2Food receives the freeze dried cultures, they are immediately stored in a freezer at a minimum temperature of -18°C. For shipping, In2Food uses dry ice as a coolant. Dry ice is the solid form of carbon dioxide (CO2) and has a temperature of -78.5°C under atmospheric pressure. The cultures are shipped in a polystyrene package with dry ice; this packaging includes a warning indicating the possible presence of remaining dry ice.
The cultures are shipped in a polystyrene package with dry ice.
Follow these guidelines upon delivery
Be cautious when unpacking the polystyrene packaging, as it may still contain dry ice. If this is the case, we recommend always following the precautions below.
- Wear gloves to avoid direct skin contact (may cause burns).
- Close the packaging and set it aside.
- The remaining dry ice will sublimate naturally.
- Dry ice is not suitable for children. Always supervise its handling.
Is there no dry ice left in the packaging upon delivery? No problem; the cultures have been properly cooled during transport.
It is important to store the freeze dried cultures in the freezer at a minimum temperature of -18°C as soon as possible after delivery. This ensures that the freeze dried cultures maintain their optimal quality.
Would you like advice on using the cultures? Or are you unsure if the cultures are optimally cooled for use?
