There has been a growing interest in recent years to apply heat pump drying (HPD)
technology to foods and biomaterials where low-temperature drying and well-controlled
drying conditions are required to enhance the quality of food products. High-valued
products, which are extremely heat-sensitive, are often freeze-dried. This is an extremely
expensive drying process (Baker, 1997). Therefore, there has been great interest in
looking at the heat pump drying system as a replacement system for freeze-dried products.
Table 20.2 presents a summary of some hybrid heat pump drying systems for
selected bioproducts.