The deacidification of pineapple juice using electrodialysis with monopolar ion exchange membranes

Abstract

The objective of this research was to study the performance of the electrodialysis using monopolar ion exchange membranes for the deacidification of pineapple juice. Based on preliminary experimental data using citric acid solution, AFN monopolar anion exchange membrane was selected for the subsequent study of the deacidification of pineapple juice. Electrodialysis of pineapple juice resulted in the reduction of the conductivity and the total acidity in the diluted stream. The deacidification value was 27.53 %. Deacidification process unexpectedly decreased the pH value from 4.01 to 3.75. However the Brix values were essentially unchanged (from 10.50 to 10.17 % Brix). A slight fluctuation in sugar compositions during electrodialysis was observed after 80 minutes of the processing. The sugar analysis was carried out using High Performance Liquid Chromatography (HPLC). HPLC analysis also showed that citric acid and malic acid compositions were always higher in the concentrated stream as compared to the diluted stream. The elemental analysis of the pineapple juice indicated that the composition of magnesium, phosphorus and potassium were reduced in the diluted stream but increased in the concentrated stream. The results from sensory evaluation test showed a higher overall acceptance for the electrodialysed pineapple juice compared to the fresh juice. The values of the overall acceptance were 66.0 % and 56.0 %, respectively. The findings showed that electrodialysis offer a better processing route and produce a more acceptable product for the deacidification of pineapple juice.