Development of high concentrated slightly acidic hypochlorous acid generator for food safety

Having a mild acidic pH of 5-6.5, Hypochlorous acid (HOCl) is a harmless disinfectant having excellent sterilizing capability for use in agriculture, medicine and food industry. Recently, the use of non-diaphragm electrolytic cell has shown great potential in producing Slightly acidic electrolyzed water (SAEW). However, the effect of various physical properties such as electrode gap, flow rate, current, bubble formation and temperature conditions are still under investigation. In this study, we produced 40 ppm SAEW by using a self-developed non-diaphragm electrolytic cell that electrolyzed 6 % Hydrochloric acid (HCl) with H 2 and Cl 2 gas as by products. The tested range of electrolyte flow rate was 2-4 mL/min. The effect of current was studied in the range of 10-15 A. The results indicate that bubble generation by increased current decreased the average convection heat transfer coefficient between the electrode and electrolyte resulting in increased temperature. Moreover, the bubbles reduced the surface area for an efficient electrolytic reaction resulting in a decrease in available chlorine concentration. Hence, an optimized flow rate of 3 mL/min at 13 A current were found to be best process conditions for SAEW generation when the electrode size is 4 cm by 14 cm. Furthermore, the produced high concentrated HOCl showed excellent sanitization efficacy against various Escherichia coli concentrations (10 5 -10 8 cfu/mL).