Efficacy of Ohmic Vacuum Concentration for orange juice concentrates and their physicochemical properties under different voltage gradients
Jeong Hyeon Hwang, Ah Hyun Jung, Sung Hee Park
Abstract
The efficacy of ohmic vacuum concentration (OVC) was evaluated for the production of value-added orange juice concentrate under different voltage gradients. OVC enables the evaporation of moisture in fruit juice at low temperatures under a vacuum. An OVC system was customized using an ohmic cell, vacuum chamber, vacuum pump, and pressure regulator. During OVC treatment, orange juice extract was ohmically heated to 66 °C using different voltage gradients (15, 20, 25, and 30 V/cm) under 27 kPa vacuum. The highest concentration of OVC was 22 min, producing 2 kg water/kg dry solid orange concentrate. However, it took 40 min to produce the same concentration using ohmic atmospheric concentration (OAC) treatment. OVC minimized the depolymerization of pectin at lower concentrations and produced a thicker orange concentrate than that by OAC. OVC also enabled a slower concentration time in which the orange concentrate was exposed to less thermal abuse. OVC did not induce discoloration or degradation of vitamin C content because the juice extract was concentrated at low temperatures for a short time. This study showed the potential of OVC to produce value-added fruit juice concentrates.