  We discuss the possible influence of gravity in the neutronization process,
$p^+ e^- \to n \nu_e$, which is particularly important as a cooling mechanism
of neutron stars. Our approach is semiclassical in the sense that leptonic
fields are quantized on a classical background spacetime, while neutrons and
protons are treated as excited and unexcited nucleon states, respectively. We
expect gravity to have some influence wherever the energy content carried by
the in-state is barely above the neutron mass. In this case the emitted
neutrinos would be soft enough to have a wavelength of the same order as the
space curvature radius.
