Czech J. Food Sci., 2009, 27(2):118-126 | DOI: 10.17221/1051-CJFS

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

Ljuba Schlemmerová², Milan Houška¹, Vladimir Špelina², Jan Strohalm¹, Aleš Landfeld¹, Hana ŠmuhaŘová², Ilona Němcová², Karel Kýhos¹, Jiřina Průchová¹, Pavla Novotná¹, Pavel Měřička³

¹ Food Research Institute Prague, Prague, Czech Republic

² State Health Institute Prague, Czech Republic

³ University Hospital Hradec Králové, Hradec Králové, Czech Republic

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 a_w = 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: D_p = D_{p, ref} × 10 ^{(Pref - P)/Z}, Z = -123.90 pH² + 1635.54 pH - 5210.49; D_{p, 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

Published: April 30, 2009  Show citation