# Postharvest Reduction of _Salmonella enterica_ on Tomatoes Using a Flagmonic Acid Emulsion
###### Abstract  
A novel produce wash consisting of pelargonic acid (PEL) emulsions was tested on tomatoes contaminated with a five-servor _Salmonella enterica_ cocktail. Ability to reduce contamination on the inoculated tomato surface, as well as mitigation of subsequent cross-contamination to uninoculated tomatoes washed in re-used/spent wash water were examined. Sanitizer efficacy was also examined over 1 and 7 d storage time (8 \({}^{\circ}\)C, recommended for red ripe tomatoes) and in the presence of 0.5% (\(w/v\)) organic load. PEL performed statistically the same (\(p\leq 0.05\)) at both 30 mM and 50 mM concentrations and resulted in greater than 1, 5 and 6 log CFU/g _Salmonella_ reductions at 0 h, 1 d and 7 d, respectively, when compared to a water-only or no rinse (NR) treatment. This was also a significantly greater reduction than was observed due to chlorine (sodium hypochlorite) and peroxyacetic acid (PAA) at all time points (\(p\leq 0.01\)). Organic load had no impact on sanitizer efficacy for all examined treatments. Finally, PEL had a deleterious impact on tomato texture. At 1 d, ca. 5 N and 7 N were required to achieve tomato skin penetration and compression, respectively, compared to >9 N and 15 N required by all other treatments (\(p\leq 0.05\)). While PEL sanitizers effectively reduced inoculated _Salmonella_ and subsequent transfer to uninoculated tomatoes, reformulation may be necessary to prevent deleterious quality impacts on produce. produce safety; postharvest wash; sanitizer; chlorine; peroxyacetic acid 202110.178.100101017817 December 2020213 January 20211 caused 125 illnesses, whereas the other outbreak sickened seven people in one Canadian province and was caused by _S._ Javiana [7]. Additionally, _S. enterica_ serovars Saintpaul, Enteriditis, Hartford, Typhimurium and Berta have also been implicated in tomato-related salmonellosis outbreaks since 2004 [8]. While good agricultural practices (GAPs) are critical to limit initial contamination of produce, postharvest sanitizers can reduce microbial cross-contamination and internalization in the event contaminated produce is introduced to postharvest wash tanks. The Produce Safety Rule (PSR) does not require the use of sanitizers during postharvest washing [9], but the North American Tomato Trade Work Group and United Fresh Produce Association's Commodity Specific Food Safety Guidelines for the Fresh Tomato Supply Chain recommend chlorine or other U.S. Environmental Protection Agency (EPA)-registered antimicrobial pesticides approved for use in postharvest wash water to control cross-contamination [10; 11]. Chlorine and peroxyacetic acid (PAA) are both strong oxidizers and two of the most frequently used sanitizers for postharvest washing [12; 13]. Chlorine, the more economical option of the two, requires robust monitoring and pH adjustment as fluctuations in pH, temperature, organic matter and other factors interfere with its efficacy [12; 13; 14; 15]. PAA is less impacted by extrinsic factors and does not require pH adjustment but is generally more expensive than chlorine [12; 13]. Both sanitizers are also highly corrosive and may pose a worker health hazard when mishandled [16]. Additionally, while chlorine and PAA can result in 4 to 5 log CFU/mL reductions of foodborne pathogens within the wash system [17], effectively reducing cross-contamination, they typically result in <1 to 2.5 log CFU/g reductions on the produce or sprout surface [14; 18; 19; 20]. For these reasons, alternative mitigation strategies are of increasing interest to produce growers and researchers alike. One such novel, alternative sanitizer being examined is pelargonic acid (PEL). PEL, also known as nonanoic acid, is a nine-carbon saturated fatty acid naturally occurring in plants, including tomatoes and animals [21; 22; 23; 24; 25]. Pelargonic acid is of interest as a sanitizer because it exhibits both antibacterial and antifungal activity [23; 26; 27]. The primary mode of antimicrobial action is membrane disruption resulting in eventual cell lysis [22; 28].