The heat pump dehydrator is a high-efficiency drying machine which is powered by the latent heat of vaporisation from surrounding air or water to dry food materials. It does not consume any fossil fuels and emits no airborne pollutants during operation. Its advantages over conventional drying techniques include energy efficiency, higher quality, and lower operating costs. It also requires a much shorter drying time, making it a great choice for applications with tight production schedules.
Research has shown that heat pump drying (HPD) enhances the quality attributes of fruits and vegetables, such as microbial safety, colour stability, vitamin C retention, volatile compounds, aroma compounds, and texture. Its effectiveness can be enhanced by using a pre-selected cyclic temperature schedule and by choosing the optimal refrigerant.
In addition, Mujumdar [17] found that the use of a reduced air temperature at the beginning and a subsequent temperature elevation as drying progresses, can accelerate drying kinetics without affecting the microbial viability of dehydrated products. This technique is particularly important for heat sensitive foods such as meats, cheeses and fruit.
Similarly, Achariyaviriya and Phoungchandang developed a computer simulation model of HPD for garlic and white mulberry leaves that was in good agreement with experimental results and adaptable to other types of low temperature drying. The model was sufficiently accurate and able to predict the influence of various factors on the quality of dried herbs. However, additional studies are required to improve the model and develop a suitable software program for application to the sub-Saharan African context. heat pump dehydrator