Many types of bread are made with oils and shortenings, which require kosher supervision as well. Basic ingredients of specially prepared dough mixes and dough conditioners are shortenings and diglycerides.
In bakeries, pans and troughs in which the dough is placed to rise and to bake are coated with grease or divider oils, which may be non-kosher. These oils often do not appear on the label.
There may also be an issue of other non-kosher products prepared and baked on the same equipment. These are some of the reasons that bread requires kosher supervision.
It is rabbinically prohibited to produce bread utilizing dairy ingredients. Since bread is frequently eaten at all meals, the rabbis were concerned that one might inadvertently eat dairy bread with a meat meal. There are two exceptions – if the bread is baked in an unusual shape or design indicating that it is dairy, or if the loaf is so small that it would be consumed at one meal.
Jewish law requires that a portion of dough or finished baked product be set aside for what is known as “challah.” After separation, the challah is burned.
This ritual is obligatory only (a) when the owner of the dough at the time of its preparation is Jewish and (b) the dough is made from flour of any of the following five grains (known as the Five Principal Species): wheat, oats, rye, spelt and barley. In addition, there is no requirement to separate challah if the batter contains less than 2.5 pounds of flour. If the batter contains at least 5 pounds of flour, a blessing is recited before separating challah.