A Comparative Study Assaying Commonly Used Sanitizers for Antimicrobial Activity against Indicator Bacteria and a Salmonella Typhimurium Strain on Fresh Produce

Abstract

With increased concerns over failures in vegetable and fruit sanitation, evaluating the efficacy of widely approved chemicals is ever more important. The purpose of this study was to determine whether sanitation treatments are equally effective against indicator bacteria and human enteric pathogens on cucumber and parsley. We provide here an experimental overview on the efficacy of common sanitation methods, which are based on peracetic acid-hydrogen peroxide, sodium dichloroisocyanurate, and the quaternary ammonium compound didecyldimethylammonium chloride. The sanitizers were tested for their activity against natural populations of total aerobic microorganisms, enterococci, and coliforms, and against the enteric pathogen Salmonella Typhimurium ATCC 14028 (which was added artificially). Results revealed that compared with washing parsley and cucumbers with water, treatments with all three sanitizers were not effective, resulting in a maximal reduction of only 0.7 log CFU of Salmonella Typhimurium. These sanitizers were also not effective in removal of natural bacteria from parsley (maximal reduction was 0.7 log CFU). Sanitation of cucumber was more successful; peracetic acid showed the most effective result, with a reduction of 2.7 log in aerobic microorganisms compared with cucumbers washed with water. Still, removal of natural bacteria from cucumbers proved more efficient than the removal of Salmonella Typhimurium. This may create a debate about the necessity of the sanitation and its contribution to safety, because sanitation of some contaminated vegetables may result in an increased likelihood of foods that, although they are given good hygienic ratings due to low microbial counts, harbor pathogens.

Resistance to essential oils affects survival of Salmonella enterica serovars in growing and harvested basil

“…Fresh fruits and vegetables are often consumed raw with minimal or no thermal processing that could destroy these pathogens (Heaton and Jones, ). Washing and disinfection of raw food is usually insufficient to assure microbial safety (Sapers, ; Lynch et al ., ; Shirron et al ., ). Thus, fresh fruits and vegetables contaminated with enteric pathogens increase the risk of food‐borne diseases.…”

Quantification of low and high levels of Salmonella enterica serovar Typhimurium on leaves

“…For example, high numbers of coliforms can readily out-compete Salmonella (Maddox, 2003). Parsley leaves, investigated in the present study, harbor high levels of natural microflora (as many as 7.3 log CFU/g) and an abundant coliform population of 6.6 log CFU/g (Shirron et al, 2009). Thus, low levels of S. Typhimurium inoculated on to parsley leaves may have been outcompeted by the natural microflora during the enrichment process which lead to false negative results.…”

“…To solve the problem many researchers used very high concentrations of pathogens (above 10 5 CFU/g) to determine how the pathogen transfers from contaminated water/soil/manure to the plants (Islam et al, 2004;Lapidot & Yaron, 2009;Solomon, Yaron, & Matthews, 2002) or to compare the effectiveness of different sanitizers (Shirron et al, 2009). The high levels of contamination applied in these experiments are usually not realistic in terms of contamination levels that possibly occur in the environment or during processing.…”

Microbial enrichment and multiplexed microfiltration for accelerated detection of Salmonella in spinach

“…Regulations imposed by the recent Food Safety and Modernization Act are intended to help prevent these outbreaks; however, current control practices, such as washing produce with sanitizing agents (e.g., chlorine), are ineffective and potentially counterproductive. Persistent pathogens may thrive after disinfection, when they can grow with less competition from indigenous microflora . Additionally, standard detection protocols underestimate pathogen populations in low and high inoculum scenarios, and biofilm formation can make detection difficult .…”

“…10,11 In 2016, major Australian grocers recalled prepackaged salads due to Salmonellacontaminated spinach. 12 Regulations imposed by the recent Food Safety and Modernization Act are intended to help prevent these outbreaks; however, current control practices, such as washing produce with sanitizing agents (e.g., chlorine), are ineffective 13 and potentially counterproductive.…”