Decontamination of fresh parsley leaves by sequential wash treatment in chlorine and lactic acid solutions

Due to concerns about the formation of carcinogenic disinfection by-products (DBPs) during decontamination process of fresh produce by chlorine based sanitisers, there has been interest in finding alternative sanitizers. Despite the intensive research, there is still no widely accepted cost effective sanitizer and most of the sanitizers in the marketplace has limited decontamination efficiency. By using parsley leaves as test vegetable, this study aimed to investigate the possibility of using a two stage sequential wash to increase the disinfection efficiency, while reducing the concentration of chlorine by application of a second stage wash with lactic acid (LA) solution. Washing of parsley leaves in 100 ±10 ppm chlorine solution for 3 min resulted in an average of 1.01±0.64 log reduction, whereas a 1 min wash in 1.0% (w/w) LA returned an average of 1.25±0.39 log reduction for TAC. Increasing washing time in chlorine or LA solutions alone did not increase the decontamination efficiency, significantly. However, 3 min wash in 100 ±10 ppm chlorine, followed by a 1 min wash 1.0% (w/w) LA (sequential wash) increased the decontamination efficiency significantly returning an average of 2.45±0.52 log reduction in total viable count. Sequential wash was also effective in reduction of artificially inoculated non-pathogenic strains of Escherichia coli, Salmonella and Listeria spp. Concentration of DBPs determined by GC-MS in wash water samples were below the limits set by United States Environmental Protection Agency.