Deacidification of passion fruit juice by electrodialysis with bipolar membrane after different pretreatments

Abstract

The reduction of acidity of passion fruit juice was investigated by electrodialysis (ED) with bipolar membranes (BM) at the laboratory and pre-industrial scale. Four states of juice were tested: initial pulpy juice, juice clarified by tangential microfiltration, twice-concentrated clarified juice, centrifuged juice. The ED performances were compared in terms of deacidification rate, current efficiency, and energy consumption. The deacidification was carried out up to pH 4.5 with satisfactory results. ED performances were lower with the pulpy and concentrated juices because of fouling of the anion-exchange membrane, which increased voltage. The differences in acidity between the juices was reduced by the pre-industrial ED stack, which involved better hydrodynamics through high flow rates and low compartment thickness. Whatever the juices, physico-chemical analysis showed that colour changed only slightly.