Purpose: This work aimed at identifying an improved method for cleaning and sanitizing a produce brush washer, which could be developed into a standard operating procedure that would be shared through extension programming to benefit growers.
Methods: Postharvest produce brush washing experiments were conducted by surface inoculating targeted zones on the equipment with nonpathogenic, streptomycin-resistant Escherichia coli MC4100 to compare different washing times and concentrations of sodium hypochlorite. Sponge Swabs (3M, Minneapolis, MN) were used for sample collection. Samples were serially diluted and plated on 3M®Aerobic Plate Count (APC) and E. coli/Coliform Petrifilm™. Experiments were conducted in triplicate and statistical analysis of variance (ANOVA) was performed.
Results: Results showed that up to five minutes of rinsing with a non-treated water in the brush washer yielded no statistical difference (P=0.707) compared to the initial inoculation. This indicated that the use of water alone is not sufficient to remove surface inoculated E.coli (control: 4.47 log CFU/96 cm2; 300 second rinse: 3.56 log CFU/96 cm2). Treatment with a five minute water rinse plus a treatment of 200 ppm sodium hypochlorite resulted a reported value of <25 CFU/96 cm2 reduction. In addition, all chlorine concentration treatments were more effective at lowering E. coli levels than just a 30-second water rinse alone. Escherichia coli reductions after 200 ppm, 100 ppm, 50 ppm, and 25 ppm chlorine treatments were 4.31, 3.53, 2.68, and 1.78 log CFU/96 cm2, respectively.
Significance: This work helped to identify optimal sanitizing conditions for a produce brush washer. This information will be used to develop a standard operating procedure for small scale production, which will improve food safety practices.