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BioMed Research International
Volume 2015, Article ID 548930, 10 pages
http://dx.doi.org/10.1155/2015/548930
Research Article

Impact of Moderate Heat, Carvacrol, and Thymol Treatments on the Viability, Injury, and Stress Response of Listeria monocytogenes

1Departamento de Ingeniería de Alimentos y del Equipamiento Agrícola, Campus de Excelencia Internacional Regional “Campus Mare Nostrum”, Escuela Técnica Superior de Ingeniería Agronómica, Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, Cartagena, 30203 Murcia, Spain
2Instituto de Biotecnología Vegetal, Campus de Excelencia Internacional Regional “Campus Mare Nostrum”, Universidad Politécnica de Cartagena, Edificio I+D+I, Muralla del Mar, Cartagena, 30202 Murcia, Spain

Received 22 April 2015; Accepted 11 June 2015

Academic Editor: Avelino Alvarez-Ordóñez

Copyright © 2015 L. Guevara et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The microbial safety and stability of minimally processed foods are based on the application of combined preservative factors. Since microorganisms are able to develop adaptive networks to survive under conditions of stress, food safety may be affected, and therefore understanding of stress adaptive mechanisms plays a key role in designing safe food processing conditions. In the present study, the viability and the sublethal injury of Listeria monocytogenes exposed to moderate heat (55°C) and/or essential oil compounds (carvacrol and thymol, 0.3 mM) treatments were studied. Synergistic effects were obtained when combining mild heat (55°C) with one or both essential oil compounds, leading to inactivation kinetics values three to four times lower than when using heat alone. All the treatments applied caused some injury in the population. The injury levels ranged from around 20% of the surviving population under the mildest conditions to more than 99.99% under the most stringent conditions. Protein extracts of cells exposed to these treatments were analysed by two-dimensional gel electrophoresis. The results obtained revealed that stressed cells exhibited differential protein expression to control cells. The proteins upregulated under these stressing conditions were implicated, among other functions, in stress response, metabolism, and protein refolding.