  We present a new calculation of neutrino emissivities and energy spectra from
a massive star going through the advanced stages of nuclear burning
(presupernova) in the months before becoming a supernova. The contributions
from beta decay and electron capture, pair annihilation, plasmon decay, and the
photoneutrino process are modeled in detail, using updated tabulated nuclear
rates. We also use realistic conditions of temperature, density, electron
fraction and nuclear isotopic composition of the star from the state of the art
stellar evolution code MESA. Results are presented for a set of progenitor
stars with mass between 15 $M_\odot$ and 30 $M_\odot$. It is found that beta
processes contribute substantially to the neutrino emissivity above realistic
detection thresholds of few MeV, at selected positions and times in the
evolution of the star.
