We study the consequences of antineutrino trapping in hot quark matter for quark star configurations with possible diquark condensation .
Due to the conditions of charge neutrality and \beta -equilibrium the flavor asymmetry increases with the number density of trapped antineutrinos .
Above a critical value of the antineutrino chemical potential of 30 MeV diquark condensation is inhibited at low densities and a two-phase structure emerges : a superconducting quark matter core surrounded by a shell of normal quark matter .
When the quark star cools down below a temperature T \sim 1 MeV , the mean free path of antineutrinos becomes larger than the thickness of the normal quark matter shell so that they get untrapped within a sudden process .
By comparing the masses of configurations with the same baryon number we estimate that the release of energy due to the antineutrino untrapping transition can be in the range of 10 ^ { 51 } \div 10 ^ { 52 } erg .