Modelling the effect of the starter culture on the growth of Staphylococcus aureus in milk

The competitive growth of a starter culture of lactic acid bacteria (Fresco 1010, Chr. Hansen, Hørsholm, Denmark) and Staphylococcus aureus was studied in milk. The lactic bacteria (LAB) were able to induce an early stationary state in S. aureus. The developed model highlights that the growth of S. aureus is inhibited when the LAB have reached a critical density. The model was tested in different conditions of temperature (from 12° to 25 °C), for various inoculum sizes of LAB and S. aureus. The results show that the model accurately quantifies the kinetics of S. aureus as a function of the starter culture.