Using One Mixer and Oven for Meat, Dairy, and Pareve

To the esteemed inquirer, The mixer is always used with cold items, whose taste does not become absorbed into the utensils. Therefore, if the bowl and beaters are clean, there is no problem using the mixer sometimes for dairy, sometimes for meat (provided no sharp items like onions or peppers are involved), or for pareve. However, at times the mixer itself, due to its rotational speed, heats the mixture. If the heat reaches a degree at which one would recoil from touching it—approximately 45 degrees Celsius—the mixer becomes designated for the type of food mixed with heat. For example, if it first heats to this degree when mixing dairy, then the utensil is considered dairy, and it is not permitted to use it initially to mix pareve food intended for a meat meal. If it does not heat to such a degree, there is no problem, and after proper cleaning it may be used. Regarding an oven, according to the rulings of the Mizrahi authorities, we present here the words of the late Rabbi Ovadia Yosef (from the book Kitzur Yalkut Yosef): "An electric baking oven in which meat or poultry is roasted is forbidden to cook or bake both meat and dairy foods in the same chamber on Shabbat, because the vapors transmit flavor from one to the other, which is prohibited. "It is permitted to bake dairy-filled cakes in such an electric oven, provided they are in a separate tray designated for dairy foods, and only occasionally, and on condition that the oven is aired out before baking for about half an hour [or a third of an hour], so that any residual moisture on the oven walls will be completely burned off by airing. This leniency applies to solid foods since many poskim hold there is no halacha of moisture in solid foods. However, it does not apply to liquids such as soup, unless the pot is well covered. In that case, permission is only granted occasionally and after airing as mentioned." [A brief note: Rabbi Yosef spoke regarding how to kasher the oven from moisture absorbed in its walls. However, it is fundamental that before any kashering process of absorbed food in walls, the utensil must first be thoroughly cleaned from any physical food residue on the surface. This is so basic in kashering that Rabbi Yosef did not even mention it in his remarks.] 

Blessings, Rabbi Nachum