ABSTRACT
Vacuum freeze-drying (VF-D) is an expensive operation-up to an order of magnitude more expensive than the next expensive drying operation, namely, spray drying. The high capital and energy costs stem from the need to generate and maintain very low temperatures and very high levels of vacuum. Therefore, this technique is justifi ed mainly for very high-value materials and high-quality/special properties products such as pharmaceuticals, nutraceuticals, enzymes, and certain products of biotechnology.
