Study of the Effect of High-Pulsed Electric Field Treatment on Vacuum Freeze-Drying of Apples

Abstract

High-pulsed electric field pretreatment on fruits and vegetables could enable the cell to break down and increase drying rate. It is hoped that it will help in solving practical problems in vacuum freeze-drying, such as large energy consumption, high production cost, and long drying time, etc. In order to study the influence of high-pulsed electric field pretreatment on vacuum freeze-drying of apples, the drying experiments for apples pretreated by a high-pulsed electric field were carried out. The effects of high-pulsed electric field pretreatment on drying rate, drying time, productivity per unit area, and specific energy consumption were studied separately. Based on the range analysis, the optimum parameters were obtained as follows: electric field strength 1000 V · cm−1, pulse width 120 µs, and pulse number 30 pulses. These were, in order of importance, pulse width, electric field strength, and pulse number. The comparison results showed that specific energy consumption was reduced by 20.46%, drying time was shortened by 22.50%, productivity per unit area was increased by 28.50%, and drying rate was improved by 27.02% over the results of the untreated group. Therefore, the result of complete drying of apples could be achieved by HPEF pretreatment.