  We investigate the phase structure of strongly interacting matter at
non-vanishing isospin before the onset of pion condensation in the framework of
the unquenched Polyakov-Quark-Meson model with 2+1 quark flavors. We show
results for the order parameters and all relevant thermodynamic quantities. In
particular, we obtain a moderate change of the pressure with isospin at
vanishing baryon chemical potential, whereas the chiral condensate decreases
more appreciably. We compare the effective model to recent lattice data for the
decrease of the pseudo-critical temperature with the isospin chemical
potential. We also demonstrate the major role played by the value of the pion
mass in the curvature of the transition line, and the need for lattice results
with a physical pion mass. Limitations of the model at nonzero chemical
potential are also discussed.
