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

• Published in: Czech Journal of Food Sciences 2009-04, Vol.27 (2), p.118-126
• Main Authors: Schlemmerová, Ljuba, Houška, Milan, Špelina, Vladimir, Strohalm, Jan, Landfeld, Aleš, ŠmuhaŘová, Hana, Němcová, Ilona, Kýhos, Karel, Průchová, Jiřina, Novotná, Pavla, Měřička, Pavel
• Format: Article
• Language: English
• Subjects: baroinactivation; Breast milk; Cow's milk; Decontamination; human milk; Mathematical models; Milk; Pasteurization; pH effects; Staphylococcus epidermidis; Substrates; Water activity
• ISSN: 1212-1800; 1805-9317
• DOI: 10.17221/1051-CJFS

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.