Pulsed Electric Fields (PEF) applications in the inactivation of parasites in food

Background Parasites are concerning food-borne pathogens. Some of them are currently not being routinely controlled in food, probably because their burden on public health is underestimated and the relative importance of different transmission routes is not completely known. Parasitic incidences could be avoided if preventive technologies were applied during food processing. Effective inactivation treatments are currently based on heat or freezing, but their side effects collide head-on with current consumer trends and new culinary habits. Scope and approach This review describes the potential application of Pulsed Electric Field (PEF) technology in the control of food-borne parasites, with the aim of reducing the viability and infectivity of parasite transmission stages without affecting food quality. Results of published studies performed on different media are critically analyzed and factors affecting the outcomes are examined. Key findings and conclusions Recent studies on the topic demonstrate the feasibility of PEF as an alternative to traditional freezing processes for the inactivation of Anisakis in fish. The development of new PEF equipment is advancing at a rapid pace, allowing for food treatment at a scale that would have been unimaginable some years ago. A review of more basic-science studies carried out on buffer media would contribute to progress in addressing the underlying drawbacks that remain to be solved. Thoroughly different fields (parasitology, physics, food engineering, water sanitation, etc.) should converge to achieve the industrial implementation of PEF for the inactivation of food-borne parasites

Impact of the resistance responses to stress conditions encountered in food and food processing environments on the virulence and growth fitness of non-typhoidal salmonellae

The success of Salmonella as a foodborne pathogen can probably be attributed to two major features: its remarkable genetic diversity and its extraordinary ability to adapt. Salmonella cells can survive in harsh environments, successfully compete for nutrients, and cause disease once inside the host. Furthermore, they are capable of rapidly reprogramming their metabolism, evolving in a short time from a stress-resistance mode to a growth or virulent mode, or even to express stress resistance and virulence factors at the same time if needed, thanks to a complex and fine-tuned regulatory network. It is nevertheless generally acknowledged that the development of stress resistance usually has a fitness cost for bacterial cells and that induction of stress resistance responses to certain agents can trigger changes in Salmonella virulence. In this review, we summarize and discuss current knowledge concerning the effects that the development of resistance responses to stress conditions encountered in food and food processing environments (including acid, osmotic and oxidative stress, starvation, modified atmospheres, detergents and disinfectants, chilling, heat, and non-thermal technologies) exerts on different aspects of the physiology of non-typhoidal Salmonellae, with special emphasis on virulence and growth fitness. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Influence of the initial cell number on the growth fitness of salmonella enteritidis in raw and pasteurized liquid whole egg, egg white, and egg yolk

Salmonella growth in egg and egg products has been widely studied, but there are still some aspects that are not fully known. The objective of this work was to study the influence of the initial cell number on the growth fitness of Salmonella Enteritidis in raw and pasteurized egg products. Growth curves of five Salmonella Enteritidis strains in raw and pasteurized egg products, starting from different initial numbers, were obtained and fitted to the Baranyi and Roberts model. The results revealed that lower initial numbers led to longer lag phases (¿) and lower maximum specific growth rates (µmax) in raw liquid whole egg. Similar results were observed in raw egg white (except for one strain). Conversely, no influence (p > 0.05) of the initial concentration on Salmonella growth parameters in raw egg yolk was observed. On the other hand, no influence of the initial number of cells on Salmonella growth fitness in commercial pasteurized liquid whole egg was observed. The results obtained demonstrate that the disappearance of this initial-dose dependency phenomenon was dependent on the intensity of the thermal treatment applied. Finally, the influence of the initial number was, in general, lower in pasteurized than in raw egg white, but large differences among strains were observed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland