Today, because the Holy Temple has been destroyed and the conditions of ritual purity in which the Kohanim ate the challah are not available, we do not actually give the challah to the kohen.

However, in remembrance of this gift and in anticipation of the future redemption and rebuilding of the Holy Temple, we still observe the mitzvah of separating the challah portion. We remove the piece of dough, but instead of eating it, we burn it, as its sacredness prohibits using it in any way.