Effect of microstructure and initial cell conditions on thermal inactivation kinetics and sublethal injury of Listeria monocytogenes in fish-based food model systems

Abstract

This document contains the post-print pdf-version of the referred paper: "Effect of microstructure and initial cell conditions on thermal inactivation kinetics and sublethal injury of Listeria monocytogenes in fish-based food model systems"

Limonene nanoemulsified with soya lecithin reduces the intensity of non-isothermal treatments for inactivation of Listeria monocytogenes

“…Most food products are complex media with several components (e.g. fat and fibers) that can affect microbial growth and inactivation 25,[53][54][55][56] . For that reason, exploratory research works aiming to understand the microbial response, rather than to validate its application in an actual food product are usually performed using standardized laboratory media.…”

The Complex Effect of Food Matrix Fat Content on Thermal Inactivation of Listeria monocytogenes: Case Study in Emulsion and Gelled Emulsion Model Systems

“…A strain cocktail of three L. monocytogenes strains, acquired from the BCCM/LMG bacteria collection of Ghent University in Belgium, was used, i.e., LMG 23773, LMG 23774 (both isolated from smoked salmon), and LMG 26484 (isolated from tuna salad). The preparation of precultures and the inoculation of the model systems was performed as described in Verheyen et al (2019a). Briefly, a purity plate was prepared for each strain by spreading a loopful of stock culture onto a BHI Agar plate [1.4% (w/v), Agar Technical No3, Oxoid Ltd., Basingstoke, United Kingdom], which was incubated at 30 • C for 24 h. Two consecutive 24 h-precultures (incubated at 30 • C) in BHI were prepared for each strain individually, starting from one colony of the respective purity plate.…”

“…Thermal inactivation experiments and sample processing were conducted as described by Verheyen et al (2019a). In short, vials containing the model systems were immersed in water baths at a constant temperature of 59, 64, or 69 • C, removed at different time intervals, and stored in ice-water prior to further processing.…”

“…Thermal processing remains one of the most used methods in food industry to ensure the microbial safety and extend the shelf life of many different food products (Pratap Singh et al, 2018). It has been shown that the presence of fat droplets inside food products significantly affects microbial inactivation kinetics during thermal processes (Verheyen et al, 2019a). Acquiring fundamental knowledge about the influence of fat content on thermal inactivation kinetics would be beneficial to acquire more insight into the influencing mechanisms of the presence of fat droplets on thermal inactivation of bacteria.…”

“…Model system composition was based on processed fish products containing a certain amount of fat (e.g., fish paté, fish salad, fish sausage) and major food microstructural elements of such food products (e.g., fat droplets, a viscoelastic matrix) were represented in the systems. In order to isolate the effect of fat content on microbial behavior, model systems with minimal variation in compositional and physicochemical factors were used, i.e., emulsions and gelled emulsions with fat contents of 5, 10, and 20% (Verheyen et al, 2018), and the obtained results were compared to those for systems containing 1% fat (Verheyen et al, 2019a). These systems spanned a fat content range of 1-20% which is relevant for a plethora of different processed fish products (Aquerreta et al, 2002;Raju et al, 2003;Echarte et al, 2004;Manthey-Karl et al, 2014).…”