Baroinactivation of Staphylococcus epidermidis – mathematical model and its verification using human and cow milk

https://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.
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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.
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