  Hot hypernuclear matter is investigated in an explicit SU(3) quark model
based on a mean field description of nonoverlapping baryon bags bound by the
self-consistent exchange of scalar $\sigma, \zeta$ and vector $\omega, \phi$
mesons. The $\sigma, \omega$ mean fields are assumed to couple to the
u,d-quarks while the $\zeta, \phi$ mean fields are coupled to the s-quark. The
coupling constants of the mean fields with the quarks are assumed to satisfy
SU(6) symmetry. The calculations take into account the medium dependence of the
bag parameter on the scalar fields $\sigma, \zeta$. We consider only the octet
baryons $N,\Lambda,\Sigma,\Xi$ in hypernuclear matter. An ideal gas of the
strange mesons $K$ and $K^{*}$ is introduced to keep zero net strangeness
density. Our results for symmetric hypernuclear matter show that a phase
transition takes place at a critical temperature around 180 MeV in which the
scalar mean fields $\sigma, \zeta$ take nonzero values at zero baryon density.
Furthermore, the bag contants of the baryons decrease significantly at and
above this critical temperature indicating the onset of quark deconfinement.
The present results imply that the onset of quark deconfinement in SU(3)
hypernuclear matter is much stronger than in SU(2) nuclear matter.
