The heat pump dehydrator is an innovative drying technology that has gained rapid interest in recent years due to its energy efficiency, improved quality, and reduced operating costs. It is also environmentally friendly as it uses renewable energy to dry food materials. However, it still has some challenges and needs further research to overcome them.
It is important to understand the concept of heat pump drying before comparing it with conventional drying processes. Heat pump dryer performance can be characterized by its thermal efficiency (COP), specific moisture removal rate (SMER) and exergy losses (Hawlader et al. 2003). These parameters are important in determining the efficiency and quality of dried products.
Various studies have shown that the quality of heat pump dried foods is comparable to those of conventionally dried products. For example, the kinetics of color and aroma degradation for herbs were significantly reduced by HPD (Prasertsan and Saen-saby 1998). The same results were obtained for apple and mushroom (Jangam et al. 2008). Additionally, the kinetics of lactone and terpenoid retention for nectarine slices was greatly reduced by heat pump drying (Sunthonvit et al. 2007).
One of the reasons for this is the optimum temperature profile used in heat pump drying. In general, a lower air temperature is utilized for the initiation of drying process and then gradually increased as drying progresses. This allows for a more gradual decrease in water content which improves the overall quality of the finished product. heat pump dehydrator