The effects of using a direct electric current on the chemical properties of gelatine gels and bacterial growth

This article comprises an investigation of the changes within the chemical properties of gelatine samples with different sodium chloride concentrations (0; 0.5; 2% w/v) that were caused by applying a direct current (DC). The pH and chloride ion concentration were measured during the storage period of 7 days, and litmus was used to visualise pH changes. Additionally, the effect of a weak DC (10, 20 and 30 mA) on the growth of Staphylococcus aureus and Yersinia enterocolitica was analysed. The results measured after the storage time indicated little pH change on the anode side of the gelatine samples with 0.5 and 2% NaCl; however, the pH was considerably reduced near the cathode side where the sodium ion concentration decreased by 34-39%. Furthermore, the application of DC inhibited bacterial growth, and this effect was strengthened by the addition of sodium chloride. This work demonstrates that the use of DC in hydrogels is a promising method of food preservation, but requires further investigation. (C) 2015 Elsevier Ltd. All rights reserved.