What does it mean when a product is lyophilized? It means it is freeze dried but there is more to the lyophilization process than freeze drying. Lyophilization is necessary to preserve products for storage. Water causes spoilage and can chemically react with the product (hydrolysis). Removing water can significantly prolong the shelf life and stability of a product. A product can be lyophilized in bulk on trays, in bulk in bottles, or in individual vials on trays. The product or sample is first dissolved in a suitable solvent. Often this solvent is water, sometimes other solvents must be added such as ethanol or n-butyl alcohol. The product is then frozen. A vacuum is applied and the ice and solvent sublime from the product and are removed from the air by the condenser. The trays on which the samples are placed are temperature controlled so the sample can be warmed slightly to aid in removing the last bit of water. The solvent chosen, the temperatures, hold times, and pressures used - are individual to each formulation and must be adjusted for maximum shelf life of the final product. Equipment for freeze drying is available from small benchtop research units to room sized production units. SP Industries and Labconco are just a few suppliers of lyophilization equipment.