Estimating Listeria monocytogenes Growth in Ready‐to‐Eat Chicken Salad Using a Challenge Test for Quantitative Microbial Risk Assessment

Abstract

Currently, there is a growing preference for convenience food products, such as ready-toeat (RTE) foods, associated with long refrigerated shelf-lives, not requiring a heat treatment prior to consumption. Because Listeria monocytogenes is able to grow at refrigeration temperatures, inconsistent temperatures during production, distribution, and at consumer's household may allow for the pathogen to thrive, reaching unsafe limits. L. monocytogenes is the causative agent of listeriosis, a rare but severe human illness, with high fatality rates, transmitted almost exclusively by food consumption. With the aim of assessing the quantitative microbial risk of L. monocytogenes in RTE chicken salads, a challenge test was performed. Salads were inoculated with a three-strain mixture of cold-adapted L. monocytogenes and stored at 4, 12, and 16°C for eight days. Results revealed that the salad was able to support L. monocytogenes' growth, even at refrigeration temperatures. The Baranyi primary model was fitted to microbiological data to estimate the pathogen's growth kinetic parameters. Temperature effect on the maximum specific growth rate (μ max) was modeled using a square-root-type model. Storage temperature significantly influenced μ max of L. monocytogenes (p < 0.05). These predicted growth models for L. monocytogenes were subsequently used to develop a quantitative microbial risk assessment, estimating a median number of 0.00008726 listeriosis cases per year linked to the consumption of these RTE salads. Sensitivity analysis considering different time-temperature scenarios indicated a very low median risk per portion (<−7 log), even if the assessed RTE chicken salad was kept in abuse storage conditions.

Effect of cold atmospheric plasma torch distance on the microbial inactivation and sensorial properties of ready-to-eat olivier salad

“…In this study, three factors were efficient in the inactivation of microorganisms; the type of the microorganism, time of plasma exposure, and the distance of the exerted plasma from the nozzle to the product surface (Calvo et al, 2020; Silvetti et al, 2021). As the results indicated, by reducing the distance between the nozzle and Olivier salad surface at equal times, microbial reduction was observed in all cases.…”

“…Also, Staphylococcus aureus accumulates in the nasal passages and on the skin of employees. (Afshari et al, 2019; Bernardo et al, 2020; CDC, 2020; Kotzekidou, 2016).…”

“…Although some studies have been accomplished on the effect of cold plasma disinfection on RTE foods (Calvo et al, 2020; Lee et al, 2020, 2021; Lin et al, 2020; Risa Vaka et al, 2019; Silvetti et al, 2021; Yadav et al, 2020), no previous studies have reported the effects of cold plasma treatment on the quality of the Olivier salad. The objective of this study was to investigate the effect of cold atmospheric plasma torch (CAPT) with different nozzle distances on microbial inactivation and sensorial properties of the Olivier salad.…”

Microbiological Safety and Shelf-Life of Low-Salt Meat Products—A Review

“…In any case, results should be analyzed with care (including fail-safe approach), considering all the constraints and assumptions introduced in simulating the natural contamination present in foods and the accurate reproduction of conditions of foods during storage, distribution, sale, and preparation. Challenge testing is a technique commonly employed in research [ 62 , 184 , 185 , 186 , 187 , 188 ]. Up to a 40% NaCl reduction was achieved during a challenge test in a pre-packed cooked meat product when it was replaced with a commercial mixture of potassium lactate and sodium diacetate without statistically affecting the shelf-life [ 166 ].…”

Temperature Effect on Listeria Monocytogenes Planktonic Growth and Biofilm-Forming Ability

“…These persistent strains have been linked to recurring contamination of finished products [10][11][12]. Although this cross-contamination transfers low levels of L. monocytogenes onto food, its psychrotrophic nature enables growth during refrigerated storage, reaching levels that might represent an increased risk to the consumer [13][14][15]. This is even more concerning if temperature fluctuation occurs in any of the production and distribution stages, or even at the household level, and if the food is a ready-to-eat product, not requiring a listericidal treatment before consumption [16][17][18].…”