Heat pump drying of food materials: A critical review

Drying is an energy intensive process and conventionally air dried products suffer from distinct loss of quality due to excessive thermal damage. Drying of fruits and vegetables with near ambient temperature and low humidity air could be a better proposition to get quality dried products. Heat pumps have been known to be energy efficient when used in conjuction with drying operations. The principal advantages of heat pump dryers (HPD) emerge from the ability of heat pumps to recover energy from the exhaust as well as their ability to control the drying air temperature and humidity. Many researchers have acknowledged the importance of HPD in producing a range of precise drying conditions for drying various heat sensitive materials such as pharmaceutical products and fruits and vegetables to get better quality. Recently, there has been a significant growth in the potential market for HPD aided by the impact of new designs under development or recently introduced into the market.