  We study the weak interaction processes taking place within a combustion
flame that converts dense hadronic matter into quark matter in a compact star.
Using the Boltzmann equation we follow the evolution of a small element of just
deconfined quark matter all along the flame interior until it reaches chemical
equilibrium at the back boundary of the flame. We obtain the reaction rates and
neutrino emissivities of all the relevant weak interaction processes without
making any assumption about the neutrino degeneracy. We analyse systematically
the role the initial conditions of unburnt hadronic matter, such as density,
temperature, neutrino trapping and composition, focusing on typical
astrophysical scenarios such as cold neutron stars, protoneutron stars, and
post merger compact objects. We find that the temperature within the flame
rises significantly in a timescale of 1 nanosecond. The increase in $T$
strongly depends on the initial strangeness of hadronic matter and tends to be
more drastic at larger densities. Typical final values range between $20$ and
$60 \, \mathrm{MeV}$. The nonleptonic process $u + d \rightarrow u + s$ is
always dominant in cold stars, but in hot objects the process $u + e^{-}
\leftrightarrow d + {\nu_e}$ becomes relevant, and in some cases dominant, near
chemical equilibrium. The rates for the other processes are orders of magnitude
smaller. We find that the neutrino emissivity per baryon is very large, leading
to a total energy release per baryon of $2-60 \, \mathrm{MeV}$ in the form of
neutrinos along the flame. We discuss some astrophysical consequences of the
results.
