  The equation of state for quark matter is derived for a nonlocal, chiral
quark model within the mean field approximation.We investigate the effects of a
variation of the formfactors of the interaction on the phase diagram of quark
matter. Special emphasis is on the occurrence of a diquark condensate which
signals a phase transition to color superconductivity and its effects on the
equation of state under the condition of beta- equilibrium and charge
neutrality. We calculate the quark star configurations by solving the Tolman-
Oppenheimer- Volkoff equations and obtain for the transition from a hot, normal
quark matter core of a protoneutron star to a cool diquark condensed one a
release of binding energy of the order of Delta M c^2 ~ 10^{53} erg. We find
that this energy could not serve as an engine for explosive phenomena since the
phase transition is not first order. Contrary to naive expectations the mass
defect increases when for a given temperature we neglect the possibility of
diquark condensation.
