Comparison of the efficacy of various sanitizers and hot water treatment in inactivating inoculated foodborne pathogens and natural microflora on mung bean sprouts

The microbiological safety of seed sprouts has been a concern in recent years following several reports of foodborne outbreaks associated with the consumption of seed sprouts. The frequent occurrence of outbreaks suggests the need for effective decontamination of seed sprouts. In this study, various decontamination methods including acidic electrolyzed water (AEW) (75 ppm available chlorine, ORP 1150 mV, pH 2.8, 180 s), acidified sodium chlorite (ASC) (1200 ppm, pH 2.3, 180 s), cetylpyridinium chloride (CPC) (2%, 180 s), ozonated water (2 ppm, 180 s), trisodium phosphate (TSP) (10%, pH 12.6, 180 s) and hot water (70 °C, 20 s) were evaluated for their efficacy against inoculated pathogens and natural mircoflora on mung bean sprouts. Results showed that the hot water treatment reduced the microbial population by 4.19, 4.35, 4.81 and 4.37 log CFU/g in Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp. and natural microflora on mung bean sprouts, respectively. On the other hand, chemical sanitizer treatments using AEW, ASC, CPC, ozonated water and TSP resulted in less than 2-log reduction in the same bacterial strains. However, hot water treatment also caused detrimental impact on the color and firmness of the bean sprouts after treatment or during storage for 4 days at 4 and 25 °C. Nevertheless, the present results indicate that, compared to the chemical sanitizers, hot water treatment has a better potential for postharvest control measure to improve the microbiological safety of raw mung bean sprouts. However, this study suggests that the method needs to be further modified to better retain the physical quality of raw mung bean sprouts. These findings may help to expand the limited pool of information on the efficacy and feasibility of decontamination treatments on sprouts.