  We consider the effect of an expanding plasma on probe matter by determining
time-dependent D7 embeddings in the holographic dual of an expanding viscous
plasma. We calculate the chiral condensate and meson spectra including
contributions of viscosity. The chiral condensate essentially confirms the
expectation from the static black hole. For the meson spectra we propose a
scheme that is in agreement with the adiabatic approximation. New contributions
arise for the vector mesons at the order of the viscosity terms.
