高强脉冲电场作用下水中溶解氧的变化反应

Change and Reaction of Dissolved Oxygen Under the Treatment of Pulsed Electric Fields

为研究高强脉冲电场(PEF)食品加工技术,以不同pH值水溶液为处理对象,研究了不同场强脉冲电场处理对其溶解氧、pH值及电导率的影响。实验结果表明:PEF作用下水会轻微电解从而导致溶解氧微量增加。中性环境中φ(O2)增加2.72 mg/L;酸性(pH=4.0)环境中,由于提供了更多的离子H+与氧气发生进一步的反应生成H2O2等活性成分,消耗了一定的氧气,φ(O2)只增加了2.21 mg/L;碱性(pH=10.0)环境中因Cl-与OH-在阳极竞争放电,OH-阳极放电生成氧气不如中性以及酸性环境强烈,φ(O2)增加不多,增幅为1.75 mg/L。pH值以及电导率的变化不大。

Pulsed electric field （PEF） related food processing technologies have been widely researched in food engineering field in recent years for its highlighted characteristics of fast, even and non-thermal treatments, especially for the purpose of sterilization. In order to explore the electrochemical reactions in PEF treated solutions, the change of dissolved oxygen,pH value and conductivity of sodium chloride solutions after subjected to PEF treatments were studied in this paper. Results showed that after PEF treatment, the content of dissolved oxygen in NaCl solution with pH value 4.0, 7.0 and 10.0 was increased by 2.21 mg/L, 2.70 mg/L and 1.75 mg/L, respectively, while the pH value and conductivity changed little under all treatments. It can be concluded that trace oxygen had been generated during PEF treatments which resulted from electrolysis reactions. Comparing the neutral condition, in acid condition （pH 4.0） ,there was more active H^＋ participating electrochemical reactions and consuming oxygen molecules which resulted in less increase of dissolved oxygen. While in alkaline conditions （ pH = 10.0）, Cl^- competed with OH^- to discharge in positive electrode and as a result, less oxygen had been generated. It implies that electrochemical reactions may exist in PEF treatment and the safety of applying this novel technique should be re-assessed further.