P Mañas1, R Pagán, F J Sala, S Condón. 1. Departamento de Producción Animal y Ciencia de los Alimentos, Tecnología de los Alimentos, Facultad de Veterinaria, Zaragoza, Spain.
Abstract
AIMS: To investigate which components of milk increase the heat resistance of Salmonella senftenberg 775W, and to explore the mechanisms that could be involved in this protective effect. METHODS AND RESULTS: The heat resistance of Salm. senftenberg was determined in a specially designed resistometer in several heating media. The molecules responsible for the thermal protective effect of milk were in the protein fraction, even in the < 3000 Da ultrafiltrate. The protective effect was lost when whey was demineralized. The former protective effect was restored when calcium or magnesium was added. Milk components protected cell envelopes of Salm. senftenberg from heat damage. CONCLUSIONS: The protein fraction and divalent cations were responsible for the protective effect of milk. The whole protective effect on Salm. senftenberg was not the result of the addition of the protective effect of each component, but the result of a synergistic effect of some of them interacting. SIGNIFICANCE AND IMPACT OF THE STUDY: This work could be useful for improving food preservation and hygiene treatments. It also contributes to our knowledge of microbial physiology.
AIMS: To investigate which components of milk increase the heat resistance of Salmonella senftenberg 775W, and to explore the mechanisms that could be involved in this protective effect. METHODS AND RESULTS: The heat resistance of Salm. senftenberg was determined in a specially designed resistometer in several heating media. The molecules responsible for the thermal protective effect of milk were in the protein fraction, even in the < 3000 Da ultrafiltrate. The protective effect was lost when whey was demineralized. The former protective effect was restored when calcium or magnesium was added. Milk components protected cell envelopes of Salm. senftenberg from heat damage. CONCLUSIONS: The protein fraction and divalent cations were responsible for the protective effect of milk. The whole protective effect on Salm. senftenberg was not the result of the addition of the protective effect of each component, but the result of a synergistic effect of some of them interacting. SIGNIFICANCE AND IMPACT OF THE STUDY: This work could be useful for improving food preservation and hygiene treatments. It also contributes to our knowledge of microbial physiology.