Fidaleo Marcello, Ventriglia Giordana
Department for Innovation in Biological, Agro-Food, and Forest Systems, University of Tuscia, Via San Camillo de Lellis, 01100 Viterbo, Italy.
Foods. 2022 Jun 15;11(12):1770. doi: 10.3390/foods11121770.
Despite the beneficial health effects of fruit juices, the high content of organic acids and low pH of some of them limit their consumption. The aim of this work was to study the deacidification of fruit juices using electrodialysis (ED) with monopolar membranes. Aqueous solutions of citric acid were used in ED deacidification experiments following a factorial design with citric acid concentration and electric current varying in the ranges of 5-25 g/L and 0.5-1 A, respectively. The design runs were characterized by a constant Faraday efficiency of 0.37 ± 0.03, suggesting that the triple-charged citrate ion (Cit) carried the electric charge through the anionic membranes. During deacidification, the pH increased in agreement with the decreasing concentration of the acid. Deacidification of pineapple juice or pineapple juice enriched with 20 g/L of citric acid using ED led to similar values of the Faraday efficiency, confirming that Cit is the main ion migrating through the anionic membrane. However, the decrease in titratable acidity during ED treatment was accompanied by a decrease in pH. Such behavior, already reported, was explained by considering proton generation during the transformation of the single (HCit) and double-charged (HCit) citrate ions into the triple-charged ion (Cit) when entering the anionic membrane.
尽管果汁对健康有益，但其中一些果汁的高有机酸含量和低pH值限制了它们的消费。这项工作的目的是研究使用带单极膜的电渗析（ED）对果汁进行脱酸。在ED脱酸实验中，使用柠檬酸水溶液，采用析因设计，柠檬酸浓度和电流分别在5-25 g/L和0.5-1 A范围内变化。设计运行的特点是法拉第效率恒定为0.37±0.03，这表明三价柠檬酸根离子（Cit）通过阴离子膜携带电荷。在脱酸过程中，pH值随着酸浓度的降低而升高。使用ED对菠萝汁或添加了20 g/L柠檬酸的菠萝汁进行脱酸，得到了相似的法拉第效率值，证实了Cit是通过阴离子膜迁移的主要离子。然而，ED处理过程中可滴定酸度的降低伴随着pH值的下降。这种已经报道过的行为，是通过考虑单电荷（HCit）和双电荷（HCit）柠檬酸根离子在进入阴离子膜时转化为三价离子（Cit）过程中产生质子来解释的。
