Synergistic Effect of Electrolyzed Water and Citric Acid Against Bacillus Cereus Cells and Spores on Cereal Grains

Abstract

The effects of acidic electrolyzed water (AcEW), alkaline electrolyzed water (AlEW), 100 ppm sodium hypochlorite (NaClO), and 1% citric acid (CA) alone, and combinations of AcEW with 1% CA (AcEW + CA) and AlEW with 1% CA (AlEW + CA) against Bacillus cereus vegetative cells and spores was evaluated as a function of temperature (25, 30, 40, 50, or 60 degrees C) and dipping time (3 or 6 h). A 3-strain cocktail of Bacillus cereus cells or spores of approximately 10(7) CFU/g was inoculated in various cereal grains (brown rice, Job's tear rice, glutinous rice, and barley rice). B. cereus vegetative cells and spores were more rapidly inactivated at 40 degrees C than at 25 degrees C. Regardless of the dipping time, all treatments reduced the numbers of B. cereus vegetative cells and spore by more than 1 log CFU/g, except the deionized water (DIW), which showed approximately 0.7 log reduction. The reductions of B. cereus cells increased with increasing dipping temperature (25 to 60 degrees C). B. cereus vegetative cells were much more sensitive to the combined treatments than spores. The effectiveness of the combined electrolyzed water (EW) and 1% CA was considerable in inhibiting B. cereus on cereal grains. The application of combined EW and CA for controlling B. cereus cells and spores on cereal grains has not been previously reported. Therefore, the synergistic effect of EW and CA may provide a valuable insight on reducing foodborne pathogens on fruits, vegetables, and cereal grains.