  The induced gravitational collapse (IGC) paradigm of long gamma-ray bursts
(GRBs) associated with supernovae (SNe) predicts a copious
neutrino-antineutrino ($\nu\bar{\nu}$) emission owing to the hypercritical
accretion process of SN ejecta onto a neutron star (NS) binary companion. The
neutrino emission can reach luminosities of up to $10^{57}$MeV s$^{-1}$, mean
neutrino energies 20 MeV, and neutrino densities $10^{31}$ cm$^{-3}$. Along
their path from the vicinity of the NS surface outward, such neutrinos
experience flavor transformations dictated by the neutrino to electron density
ratio. We determine the neutrino and electron on the accretion zone and use
them to compute the neutrino flavor evolution. For normal and inverted
neutrino-mass hierarchies and within the two-flavor formalism
($\nu_{e}\nu_{x}$), we estimate the final electronic and non-electronic
neutrino content after two oscillation processes: (1) neutrino collective
effects due to neutrino self-interactions where the neutrino density dominates
and, (2) the Mikheyev-Smirnov-Wolfenstein (MSW) effect, where the electron
density dominates. We find that the final neutrino content is composed by
$\sim$55% ($\sim$62%) of electronic neutrinos, i.e. $\nu_{e}+\bar{\nu}_{e}$,
for the normal (inverted) neutrino-mass hierarchy. The results of this work are
the first step toward the characterization of a novel source of astrophysical
MeV-neutrinos in addition to core-collapse SNe and, as such, deserve further
attention.
