Disinfection efficacy of electrolyzed oxidizing water on brown rice soaking and germination

Brown rice is prone to be contaminated by microorganism and it is a common problem during brown rice soaking and germination. In this study, efficacy of acidic electrolyzed water (AEW) and slightly acidic electrolyzed water (SAEW) with different available chorine concentrations (ACC) on inactivation of natural microbiota and inoculated Bacillus cereus spores on brown rice was determined. Effect of replacing treatment solution during soaking and properties of brown rice after treatment was also determined. Brown rice was treated with AEW and SAEW at ACC of 50, 100 and 150 mg/L for 30 or 60 min at the ratio of 1: 5 (w/v) to remove the natural microbiota and then soaked in sterilized deionized water for the following 24 h. The results showed AEW with ACC of 150 mg/L for 30 or 60 min treatment decontaminated natural microbiota completely with no significant impact on properties of brown rice and could be used to remove microbiota on brown rice for the following inoculation trials. AEW and SAEW with ACC of 50, 100 and 150 mg/L were used to soak brown rice for 24 h and achieved the reduction of B. cereus spores inoculated on brown rice about 1.6–3.3 logs. AEW and SAEW with ACC of 50 and 100 mg/L replaced for 5 times during brown rice soaking achieved additional 2.40, 2.87 and 2.80, 2.78 log reductions respectively, in comparison with electrolyzed oxidizing (EO) waters with the same ACC soaked brown rice without replacement. However, germination potential and germination rate of brown rice were negatively affected by AEW for 24 h soaking. Results suggested that the application of SAEW to soak brown rice could reduce the microorganism with no adverse effect or even promote the properties of brown rice and hence could be used safely in food industry for brown rice soaking. Other approaches will be needed to combine with EO water for brown rice germination to reduce microbiota.