Study on the Quality Improvement of Acidic Citrus Juices, Citrus natsudaidai and Citrus grandis, by Bipolar Membrane Electrodialysis

摘要

Acidic citrus juices obtained from C. natsudaidai and C. grandis were electrodialyzed with bipolar and organic acid selective membrane (ion exchange membrane) cartridges. The pH levels of the acidic citrus juices gradually increased to 14.5% (C. grandis) and 25.2% (C. natsudaidai) by electrodialysis with the bipolar membranes, while levels remained consistent when organic acid selective membranes were applied. The total acidity levels decreased more with the organic selective membrane than with the bipolar membrane. Conductivity rose with the bipolar membranes while the value continued to fall rapidly with the organic selective membranes. Sugar and flavonoid contents remained relatively unchanged, without any significant differences before and afterelectrodialysis with each membrane. Also, ion contents were almost unchanged with the bipolar membranes and the electrolyte, K_2SO_4, as compared to rapid changes in sodium and potassium levels with the organic selective membranes and the electrolyte, K_2SO_4. In summary, the use of bipolar membranes provided juice with better sensory quality than that of the organic acid selective membranes.