  We study the effect of neutrino trapping on the phase diagram of dense,
locally neutral three-flavor quark matter within the framework of a
Nambu--Jona-Lasinio model. In the analysis, dynamically generated quark masses
are taken into account self-consistently. The phase diagrams in the plane of
temperature and quark chemical potential, as well as in the plane of
temperature and lepton-number chemical potential are presented. We show that
neutrino trapping favors two-flavor color superconductivity and disfavors the
color-flavor-locked phase at intermediate densities of matter. At the same
time, the location of the critical line separating the two-flavor
color-superconducting phase and the normal phase of quark matter is little
affected by the presence of neutrinos. The implications of these results for
the evolution of protoneutron stars are briefly discussed.
