A new freeze-drying method in a sterilisable closed reactor vessel not only yields lump-free fine powders, but also makes the production process more efficient in quality, application in equipment and safer - because dust-free for process, operator and environment
Hosokawa Micron BV developed this closed active freeze-drying technology for powder production in food companies and the pharmaceutical industry.
With this alternative to current freeze-drying methods, the company takes a step towards a sheathed and stirred dryer and collection filter. The material to be freeze-dried is quickly frozen in the reactor vessel, after which the required energy is fed through the jacket and then efficiently distributes itself to the product. This is done by a stirring element that moves the dried material to the filter in the form of a fine loose powder.
The active freeze-drying system dries solutions, dispersions, pasty products and wet solids and can be used for e.g. proteins, collagens, electrolytes and antibiotics and other active pharmaceutical ingredients (APIs) that need to be dried into fine powders. The company has since conducted tests with the closed freeze-drying technology for enzymes, proteins, bread dough, mushrooms, herb and watercress extracts, carrots, garlic, insects, soups, flavours and cellulose fibres.
Attention from food and pharma
The closed freeze-drying system is attracting the attention of the food industry and especially pharmaceutical companies, observes Gerard Geurtsen, Senior Application Engineer at Hosokawa Micron BV. "Every production step takes place within a single sterile closed chamber. There is no dust to compromise operator safety. Nothing can enter the sealed system and contaminate the product. The moist product is transferred from a reactor vessel, so there is no risk of contamination - as can occur with manual handling - and the product can be processed aseptically. When the vacuum is lifted, the finished dry powder is directly discharged into a container. This was sterilised internally along with the entire system before the product was fed into the system. No additional containment measures were required to protect the operators or the product."
Clump-free, fine and uniform powders as end product
The company's technology, specialising in design and production of machines and systems for mechanical and thermal processing of powders, results in a loose free-flowing powder without an additional grinding process. This is the case with tray drying, which produces a hard and crusty material as an end product. Classification may also not be necessary as the particle size of the final product is often very fine and uniform. The product is often very porous and its easy decomposition makes application in injectables, for example, easy. Because it is not necessary to grind, the product is not damaged. The technology can dry even very sensitive, finely structured products and living organisms without damaging them.
Aseptic processing
The completely closed system enables aseptic processing and is easy to clean without the use of operators in special suits. The cleaning and sterilisation process starts via nozzles in the drying chamber after the batch is completed. SIP (Steam In Place) can be achieved by pressurised steam or vaporised hydrogen peroxide.
Food and pharmaceutical manufacturers can process large product volumes with this 'single operator' system because of short drying times due to high heat transfer, easy filling and unloading and quick system cleaning.
Fast and less labour-intensive
The active freeze-drying process is often faster and always less labour-intensive than the traditional tray freeze-drying process, and it produces lump-free free-flowing powders in just one process step. This leads to shorter and easier processing times which saves companies time and money. The system is also compact and simple, requiring little floor space and less equipment.
Hosokawa Micron BV has test facilities for conducting initial product testing, product development and customer trials. Gerard Geurtsen clarifies, "Our test centre includes units for 1, 5, 60 and 800 litres which are available for customer testing and to demonstrate scale-up capabilities." The company has now conducted tests with the closed freeze-drying technology for enzymes, proteins, bread dough, mushrooms, herb and watercress extracts, carrots, garlic, insects, soups, flavours and cellulose fibres.
