Abstract: Core-collapse supernovae are one of the most complex phenomena in the universe. Not only are they one of the sites of the production of the heavy elements which enable the existence of life, but their cores are also one of the densest environments we can indirectly probe. At such densities, the matter may no longer consist only of hadronic degrees of freedom but undergo a phase transition to quark matter. In this talk, I will discuss the implications of such a transition on the neutrino emission from core-collapse supernovae and how the detection of such a signal on Earth can be used to point to the location of the supernova and set stringent limits on the absolute active neutrino mass.