Disinfection of Salmonella enterica typhimurium and Escherichia coli O157:H7 on radish microgreen during spray irrigation with chlorinated water

Microgreens have become a recent trend in industrial and household production. They are micro- sized greens harvested when the seeds of various vegetables, grains and plants germinate and reach 1-3 inches long after the formation of their first true leaves. The purpose of this study was to determine the efficacy of spray application of chlorinated water before harvest on population of Salmonella enterica Typhimurium and Escherichia coli O157:H7 on radish microgreen. Seeds were sow in perlite inoculated with nalidixic acid resistant strains. During growth, microgreens were sprayed with chlorinated water at three different concentrations (0.50, 1.00, and 2.00 ± 0.05 ppm free chlorine). Spray application of chlorinated water was performed on microgreens once (day 9), twice (day 8 and 9), three (day 7, 8, and 9) and four times (day 6, 7, 8, and 9). The population of aerobic mesophilic bacteria (AMB) and total yeast and mold counts (TYMC) were also determined. Salmonella and E. coli O157:H7 populations were detected lower with the increase of chlorine concentration. Chlorinated water reduced Salmonella and E. coli O157:H7 populations up to 1.1 log CFU/g (P < 0.05) and 0.9 log CFU/g (P > 0.05), respectively. AMB population decreased up to 1.1 log CFU/g (P > 0.05). No effect on population of TYMC was seen at any concentration. Spray application of chlorinated water during microgreen growth may help to reduce microbial load but cannot be used as only control measures.