GEA, Germany, launched a new nitrogen freezing pilot plant for bacteria, giving food and dairy processors the opportunity to trial new technology in their own plants before investing in production-scale equipment. By freezing bacteria into pellets before drying, GEA offers greater flexibility and a higher active cell count through better utilization of their fermentation lines and freeze dryers.

Many dairy and food processors use live bacteria as part of their production process (e.g., yogurt or cheese). Traditionally, they have kept their own strains of bacteria and transferred them from one batch to the next. However, as more specialized strains of bacteria have emerged, so too has the need to distribute them more widely. This is typically done by freezing them to -50°C and then storing under temperature-controlled conditions. This, however, requires a continuous cold chain.

Freeze-dried bacteria can be transported and stored at ambient temperature and rehydrated as required. On the other hand, freeze drying bacteria is a long process requiring several hours to freeze, then an additional 48-72 hours for the lyophilization process to be completed.

With its new pilot plant, GEA freezes the bacteria in droplets using a liquid nitrogen bath outside the freeze dryer, then dries the pellets via the normal procedure. Rather than freezing all of the bacteria in a single batch, it can be collected from a continuous stream improving flexibility and equipment utilization. Plus, fermentation and freeze drying are separate, so the freeze dryer does not need to be available when the product is frozen.

“Although there is a cost for the liquid nitrogen, this is more than offset by the optimized utilization of the freeze dryer,” says Morten Pedersen, area sales manager for GEA Process Engineering. “Freeze dryers are expensive, so we need to make sure customers are getting the best possible output from them. Bacteria that is frozen quickly via liquid nitrogen and dried in this way is retaining twice as many viable cells than other techniques. This product is more effective than other options, and ultimately, reduces the customer’s costs.”

The new pilot plant has a simple design, is easy to use and can be cleaned in place.

“We are absolutely committed to this technology and want our customers to have the opportunity of trying it out for themselves in their own factories,” says Morten.