  We revisit the hypothesis of a possible line structure in the Hawking
evaporation spectrum of black holes. Because of nonperturbative quantum gravity
effects, this would take place arbitrarily far away from the Planck mass. We
show, based on a speculative but consistent hypothesis, that this naive
prediction might in fact hold in the specific context of loop quantum gravity.
A small departure from the ideal case is expected for some low-spin transitions
and could allow us to distinguish several quantum gravity models. We also show
that the effect is not washed out by the dynamics of the process, by existence
of a mass spectrum up to a given width, or by the secondary component induced
by the decay of neutral pions emitted during the time-integrated evaporation.
