Drying by lyophilization is a special low-temperature drying method. The liquid is frozen and the “ice” is then broken (or “granulated”) into small pieces that are dried on a plate or a transporter by sublimation, without passing through a liquid state.
This process is done in a vacuum chamber indirectly heated by radiation with an infrared light, microwaves or electrical plates. The evaporated water is condensed into ice. Due to the low temperature, the product’s organoleptic properties remain intact.
Due to high investment and operating costs, this drying method involves high operating costs. For this reason, it is reserved for products of high quality or that have high added value (or for products that are difficult to dry with other methods). Typical examples are top quality coffee extracts, fruit juices and frozen vegetable that are sliced or in pieces.