  The behavior of strange matter in the frame of the SU(3)Polyakov-loop
extended Nambu-Jona-Lasinio model including $U_A(1)$ anomaly is considered. We
discuss the appearance of a peak in the ratio of the number of strange mesons
to non-strange mesons known as the "horn". The PNJL model gives a schematic
description of the chiral phase transition and meson properties at finite
temperature and density. Using the model, we can show that the splitting of
kaon and anti-kaon masses appears as a result of introduction of density. This
may explain the difference in the $K^+/\pi^+$ ratio and $K^-/\pi^-$ ratio at
low $\sqrt{s_{NN}}$ and their tendency to the same value at high
$\sqrt{s_{NN}}$. We also show that the rise in the ratio $K^+/\pi^+$ appears
near CEP when we build the $K^+/\pi^+$ ratio along the phase transition diagram
and it can be considered as a critical region signal.
