Inactivation of Alicyclobacillus acidoterrestris spores in aqueous suspension and on apples by neutral electrolyzed water

Alicyclobacillus acidoterrestris can be difficult to control in fruit juices as their spores survive juice pasteurization temperatures and may subsequently germinate and grow. Contaminated fruits can be regarded as a major source of spoilage caused by A. acidoterrestris in fruit juices. The objective of this study was to evaluate the efficacy of neutral electrolyzed water (NEW) in reducing the number of A. acidoterrestris spores in aqueous suspension and on surface-inoculated apples. Its effectiveness was compared with that of sodium hypochlorite (SH) solutions at free chlorine concentrations of 50 and 200 mg/L. Viable spore counts in test suspensions were significantly (P < 0.05) reduced after exposure to NEW (200 mg/L free chlorine) for 1 min. However, NEW (50 mg/L free chlorine) and SH solutions were unable to significantly (P > 0.05) reduce the number of viable spore during the same exposure period. More than 5 log reduction in spore counts was achieved by NEW solution containing 200 mg/L free chlorine after 5 min of exposure. Exposure to NEW solutions for 3 min yielded more than 4 log reductions in the number of viable spores on apple surfaces. At the same concentrations of free chlorine, NEW was three to more than ten-fold effective than SH in reducing viability of A. acidoterrestris spores in aqueous suspension and on apple surfaces. This finding suggests that NEW can be considered as an effective disinfectant for the control of A. acidoterrestris on fruits.