Comparison of a continuous flow dipper well and a reduced water dipper well combined with ultraviolet radiation for control of microbial contamination

•Per 10s use, reduced water dipper wells (RW-DW) use 25% less water than conventional DW (C-DW).•RW-DW reduces Escherichia coli in skim milk on stainless steel utensils better than C-DW.•RW-DW plus UV-C reduces E. coli an additional 0.36-1.68 log10 during continuous use.

Continuous flow (CF) dipper wells, or small countertop sinks, are used in the foodservice industry for rinsing utensils such as stirring spoons and dishers. In addition, these dipper wells are designed as continuous flow not only to rinse and clean but to also control for the buildup of microorganisms. Here, we evaluate a reduced water (RW) dipper well - with and without ultraviolet subtype C (UV-C) disinfection - for control and inactivation of Escherichia coli present on a stainless steel utensil. Overall, the RW dipper well (with and without UV-C) performed significantly better than the CF dipper well for removal of E. coli in 10% skim milk medium at various exposure and rinse times. More specifically, at 5, 10, and 30 s, the RW dipper well without UV-C achieved 1.04, 1.72, and 2.03 greater log10 (CFU/ml) reduction in E. coli compared to the CF dipper well at the same treatment times, respectively. When combined with UV-C, the RW dipper well increased reduction of E. coli by 0.36-1.68 log10 (CFU/ml) over prolonged use (i.e. 2 h continuous use). Moreover, the RW dipper well combined with UV-C may provide a preventative step to reduce the growth and/or persistence of bacteria on the utensil as well as the dipper well reservoir, especially for E. coli in 10% skim milk medium. To our knowledge this is the first study to evaluate the efficacy of dipper wells - both RW and CF systems - in the removal of E. coli on a stainless steel utensil.