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Your search keyword '"Paula M. Periago"' showing total 2 results
Start Over Author "Paula M. Periago" Journal frontiers in microbiology
2 results on '"Paula M. Periago"'

1. The Different Response to an Acid Shock of Two Salmonella Strains Marks Their Resistance to Thermal Treatments

Author

Marta Clemente-Carazo, José-Juan Leal, Juan-Pablo Huertas, Alberto Garre, Alfredo Palop, and Paula M. Periago

Subjects
foodborne pathogens, acid shock, pasteurization, cross-resistance, stress adaptation, Microbiology, QR1-502
Abstract

Microbial cells respond to sub-lethal stresses with several physiological changes to increase their chance of survival. These changes are of high relevance when combined treatments (hurdle technology) are applied during food production, as the cells surviving the first hurdle may have greater resistance to subsequent treatments than untreated cells. In this study, we analyzed if Salmonella develops increased resistance to thermal treatments after the application of an acid shock. We compared the heat resistance of acid-shocked (pH 4.5 achieved with citric acid) Salmonella cells with that of cells maintained at pH 7 (control cells). Thermal treatments were performed between 57.5 and 65°C. We observed a differential response between the two strains studied. Acid-shocked cells of Salmonella Senftenberg exhibited reduced heat resistance, e.g., for a treatment at 60.0°C and pH 7.0 the time required to reduce the population by 3 log cycles was lowered from 10.75 to 1.98min with respect to control cells. Salmonella Enteritidis showed a different response, with acid-shocked cells having similar resistance than untreated cells (the time required to reduce 3 log cycles at 60.0°C and pH 7.0 was 0.30min for control and 0.31min for acid-shock cells). Based on results by differential plating (with or without adding the maximum non-inhibitory concentration of NaCl to the recovery medium), we hypothesize that the differential response between strains can be associated to sub-lethal damage to the cell membrane of S. Senftenberg caused by the acid shock. These results provide evidence that different strains of the same species can respond differently to an acid shock and highlight the relevance of cross-resistances for microbial risk assessment.

Published
2021
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2. High Heating Rates Affect Greatly the Inactivation Rate of Escherichia coli

Author

Juan-Pablo Huertas, Arturo Esnoz, Arantxa Aznar, Asunción Iguaz, Alfredo Palop, Paula M. Periago, Pablo S. Fernández, and Ministerio de Economía, Industria y Competitividad

Subjects
0301 basic medicine, Microbiology (medical), Food industry, Thermoresistometer, 3309 Tecnología de Los Alimentos, Thermal resistance, 030106 microbiology, lcsh:QR1-502, Heat resistance, medicine.disease_cause, Microbiology, lcsh:Microbiology, 03 medical and health sciences, 0404 agricultural biotechnology, Heat exchanger, Escherichia coli, medicine, Tecnología de los Alimentos, Food science, heat exchanger, Original Research, Chemistry, business.industry, heat resistance, Heating rate, 04 agricultural and veterinary sciences, 040401 food science, Biotechnology, Volumetric flow rate, Pilot plant, business
Abstract

Heat resistance of microorganisms can be affected by different influencing factors. Although, the effect of heating rates has been scarcely explored by the scientific community, recent researches have unraveled its important effect on the thermal resistance of different species of vegetative bacteria. Typically heating rates described in the literature ranged from 1 to 20°C/min but the impact of much higher heating rates is unclear. The aim of this research was to explore the effect of different heating rates, such as those currently achieved in the heat exchangers used in the food industry, on the heat resistance of Escherichia coli. A pilot plant tubular heat exchanger and a thermoresistometer Mastia were used for this purpose. Results showed that fast heating rates had a deep impact on the thermal resistance of E. coli. Heating rates between 20 and 50°C/min were achieved in the heat exchanger, which were much slower than those around 20°C/s achieved in the thermoresistometer. In all cases, these high heating rates led to higher inactivation than expected: in the heat exchanger, for all the experiments performed, when the observed inactivation had reached about seven log cycles, the predictions estimated about 1 log cycle of inactivation; in the thermoresistometer these differences between observed and predicted values were even more than 10 times higher, from 4.07 log cycles observed to 0.34 predicted at a flow rate of 70 mL/min and a maximum heating rate of 14.7°C/s. A quantification of the impact of the heating rates on the level of inactivation achieved was established. These results point out the important effect that the heating rate has on the thermal resistance of E. coli, with high heating rates resulting in an additional sensitization to heat and therefore an effective food safety strategy in terms of food processing. This research was financially supported by the Ministry of Economy and Competitiveness of the Spanish Government and European Regional Development Fund (ERDF) through project AGL2013-48993-C2-1-R

Published
2016
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