  The thermodynamic characteristics of hot $\beta$-equilibrium electrically
neutral three-flavor quark matter at neutrino confinement are investigated. For
the thermodynamic description of such a quark-lepton system, the local SU (3)
Nambu--Jona-Lasinio (NJL) model is used, in which also takes into account the
't Hooft interaction, leading to the quark flavor mixing effect. The energy
density $\varepsilon$ and pressure $P$ of quark matter are numerically
determined for different values of the baryon number density in the range
$n_B\in[0.02{\div}1.8]$ fm$^{-3}$ and temperatures in the range
$T\in[0{\div}100]$ MeV. The results obtained are compared with the results of
cold quark matter calculated within the framework of the same model, but under
the assumption that all neutrinos have already left the system. The dependence
of the contribution of individual quark flavors to the baryon charge of the
system at different temperatures is discussed. Both isothermal and adiabatic
speeds of sound in hot quark matter are determined depending on the baryon
number density.
