Radio frequency-vacuum drying of kiwifruits: kinetics, uniformity and product quality

A radio frequency (RF) vacuum technology is proposed for drying kiwifruit slices using a 27.12 MHz, 3 kW RF-vacuum drying system. The results demonstrated that electrode gap, vacuum pressure and sample thickness had major effects on the RF-vacuum drying. The RF-vacuum drying was associated with internal heating and rapid drying, resulting in 65% reduction of hot air (60ºC) drying time. Moreover, kiwifruits dehydrated by RF-vacuum drying were associated with better color stability, higher vitamin C retention and higher rehydration capacity (P<0.05). Overall, the RF-vacuum drying process may provide a more effective and practical method for high-quality dehydration of kiwifruits. Keywords: radio frequency-vacuum drying; hot air; moisture content distribution; moisture effective diffusivity; quality