Lyophilization - Freeze-drying for sensitive products
Herbs, fruits and medicines have one thing in common: they can all be preserved by lyophilization. Freeze drying is an established process in many fields, particularly for preserving sensitive products and it often offers the most advantages compared to other drying processes. For many foods, such as freshly picked herbs or mushrooms, freeze-drying has become the standard method of preservation today. Lyophilization, however, is also used to preserve pharmaceutical products such as medicines and vaccines. This process requires a particularly deep vacuum. Unlike conventional vacuum drying, a freeze-dried product is produced by sublimation: ice passes directly into the gas phase. This means that the product is dried in a particularly gentle manner.
Freeze-drying is extensively used in the production of foodstuffs and pharmaceutical ingredients. Unsurprisingly, products such as these often tend to be sensitive to temperature or humidity. The best known is probably soluble coffee, often called ‘instant coffee’. Here, coffee extract is processed by means of lyophilization in such a way that the consumer only has to dissolve the resulting powder in hot water. The powder can be kept in its packaging for years without being refrigerated.
Typical fields of application for freeze-drying
Freeze-drying retains the aroma and color of fruit. For example, it is possible to top pizzas with long-life mushroom slices that are in no way inferior to fresh vegetables. The long shelf life of herbs and spices is also a huge bonus. The essential oils contained in the herbs are also preserved as flavor carriers.
Lyophilization offers advantages in pharmaceutical production and biotechnology, especially for temperature-sensitive vaccines, antibiotics and bacteria. After processing, which is performed directly in vials or syringes, the preparations can be dissolved within seconds if required.