A rapid method for determination of Staphylococcus aureus based on milk coagulation by using a series piezoelectric quartz crystal sensor Original Research Article

A series piezoelectric quartz crystal (SPQC) sensor was utilized to determine the number of bacteria based on the coagulation of milk in which Staphylococcus aureus (S. aureus) had grown. Compared with the method based on a PQC coated with a thin film, earlier it had the advantage that no dilution of the medium was needed and cease of the oscillation can be avoided throughout the experiment. Moreover, it was rapid, the turning-point time (TT) for quantitative detection which was the time at which the frequency begins to return after a drop in response curve was easy to determine and there was a good relation between TT and logarithm of the initial concentration of S. aureus in the range of 2.4×102–2.4×105 cells ml−1.