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Título
Behavior of Shiga-toxin-producing Escherichia coli in ewe milk stored at different temperatures and during the manufacture and ripening of a raw milk sheep cheese (Zamorano style)
Autor
Facultad/Centro
Área de conocimiento
Título de la revista
Journal of Dairy Science
Número de la revista
8
Datos de la obra
Otero, V., Santos, J. A., Rodríguez-Calleja, J. M., & García-López, M.-L. (2022). Behavior of Shiga-toxin-producing Escherichia coli in ewe milk stored at different temperatures and during the manufacture and ripening of a raw milk sheep cheese (Zamorano style). Journal of Dairy Science, 105(8), 6527-6535. https://doi.org/10.3168/JDS.2021-21613
Editor
Elsevier
Fecha
2022
ISSN
0022-0302
Résumé
[EN] This study was conducted to assess the survival of 2 wild Shiga toxin-producing Escherichia coli strains (one serotype O157:H7 and one non-O157:H7) in ewe milk stored at different conditions and to examine the fate of the O157 strain during the manufacture and ripening of a Spanish sheep hard variety of raw milk cheese (Zamorano). The strains were selected among a population of 50 isolates, which we obtained from ewe milk, because of their high resistance to 0.3% lactic acid. Both strains were inoculated (approximately 2 log10 cfu/mL) in raw and heat-treated (low-temperature holding, LTH; 63°C/30 min) ewe milk and stored for 5 d at 6, 8, and 10°C and also according to a simulation approach for assessing the effects of failures in the cold chain. The minimum growth temperature for the O157:H7 strain in LTH and raw ewe milk was 8°C. For the non-O157:H7 strain, the lowest temperature showing bacterial growth in LTH ewe milk was 6°C, but it did not grow at any of the tested conditions in raw milk. It appears that the O157 strain was more susceptible to cold stress but was likely a better competitor than the non-O157 strain against the milk autochthonous microbiota. For manufacture of Zamorano cheese, raw milk was inoculated with approximately 3 log10 cfu/mL, and after 2 mo of ripening at 10 to 12°C, the cheeses showed the expected general characteristics for this variety. The O157:H7 strain increased 0.9 log10 cfu/g after whey drainage and during ripening and storage decreased by 2.9 log10 cfu/g. Nevertheless, its detectable level (estimated at 6.2 cfu/g) after 2 mo of ripening suggests that Zamorano cheese manufactured from raw ewe milk contaminated with E. coli O157:H7 could represent a public health concern.
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ID proyecto
- info:eu-repo/grantAgreement/MICINN/Programa Nacional de Investigación Fundamental/AGL2011-26118/ES/ESCHERICHIA COLI ENTEROPATOGENICO COMO PATOGENO EMERGENTE DE TRANSMISION ALIMENTARIA: CARACTERIZACION DEL PELIGRO ASOCIADO A SU PRESENCIA EN ALIMENTOS//
- info:eu-repo/grantAgreement/Junta de Castilla y León/Programa Nacional de Fortalecimiento Institucional/GR155-1/ES/Aplicación de técnicas moleculares a la detección y epidemiología de microorganismos patógenos aislados de alimentos, agua y muestras clínicas en Castilla y León//
- info:eu-repo/grantAgreement/Junta de Castilla y León/ Programa Nacional de Fortalecimiento Institucional/GR155-2/ES/Aplicación de técnicas moleculares a la detección y epidemiología de microorganismos patógenos aislados de alimentos, agua y muestras clínicas en Castilla y León//
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