Per <a href="http://www.physor...066.html">http://www.physor...066.html</a> jets may form right outside black holes that have a retrograde spin or which spin in the opposite direction from their accretion disk.So the accretion disk would be composed of matter being pulled into the black hole, including electrons, whereas jets spin in the opposite direction, indicating opposite charge (positrons) which would be anti-matter.