Baroinactivation of Staphylococcus epidermidis – mathematical model and its verification using human and cow milk
L. Schlemmerová, M. Houška, V. Špelina, J. Strohalm, A. Landfeld, H. Šmuhařová, I. Němcová, K. Kýhos, J. Průchová, P. Novotná, P. Měřičkahttps://doi.org/10.17221/1051-CJFSCitation:Schlemmerová L., Houška M., Špelina V., Strohalm J., Landfeld A., Šmuhařová H., Němcová I., Kýhos K., Průchová J., Novotná P., Měřička P. (2009): Baroinactivation of Staphylococcus epidermidis – mathematical model and its verification using human and cow milk. Czech J. Food Sci., 27: 118-126.
Staphylococcus epidermidis, commonly found on the human skin, may contaminate human milk. High-pressure pasteurisation of human milk under normal temperature preserves the majority of its protective agents. The objective of this study was to acquire baroinactivation data and develop a model for model solutions of pH = 6.4 to 7.2 and water activity aw = 0.99, in which baroinactivation of Staphylococcus epidermidis takes place. Decontamination data manifested exponential kinetics and the resulting model was described by the following equations: Dp = Dp, ref × 10 (Pref – P)/Z, Z = –123.90 pH2 + 1635.54 pH – 5210.49; Dp, ref = –8.89 pH2 + 121.02 pH – 408.34. The developed model was verified using pasteurised human milk and UHT-treated skimmed cow milk. The agreement between the experimental data and model-based prediction was very good for human milk. It was proved that the application of a pressure of 350 MPa for 10 min decreased the concentration of the working suspension of S. epidermidis in the model substrate by a minimum of five orders.Keywords:Staphylococcus epidermidis; baroinactivation; human milk