  We investigate the quark mass dependence of baryon masses in 2+1 flavor
lattice QCD using SU(3) heavy baryon chiral perturbation theory up to one-loop
order. The baryon mass data used for the analyses are obtained for the
degenerate up-down quark mass of 3 MeV to 24 MeV and two choices of the strange
quark mass around the physical value. We find that the SU(3) chiral expansion
fails to describe both the octet and the decuplet baryon data if
phenomenological values are employed for the meson-baryon couplings. The SU(2)
case is also examined for the nucleon. We observe that higher order terms are
controlled only around the physical point. We also evaluate finite size effects
using SU(3) heavy baryon chiralperturbation theory, finding small values of
order 1% even at the physical point.
