We have finished siman 3, and are discussing the concept of gerufah u’ketumah, which, for our purposes, means putting up a blech. We learned (S0039) that there are differences between Ashkenazim and Sephardim regarding how cooked the food must be before putting it directly on a fire (i.e., without gerufah uketumah) before Shabbos. This machlokes is based on a machlokes in the Gemara, between the Chachomim and Chananya. The Gemara discusses whether one may leave food on the stove which is already cooked to the level of ma’achal ben derusai without the stove being gerufah u’ketumah. Chananya holds it may remain on the stove, and the Chachomim opinion holds it cannot remain on the stove unless it is fully cooked.
In addition, the Chachomim are concerned for mitztameik veyafeh lo. This is the concept that certain foods can be fully cooked at the onset of Shabbos, but improve by remaining on the fire. For example, a cholent can be ready to eat on Friday night, but will improve by remaining on the fire overnight until Shabbos morning. The Chachomim hold that even when the food is fully cooked at the outset of Shabbos, if remaining on the fire is beneficial to the food item (mitztameik veyafeh lo), it cannot remain on the fire unless the fire is gerufah uketumah. Alternatively, if the food is fully cooked at the onset of Shabbos, and remaining on the fire is not beneficial to the food item, it may remain on the fire even without gerufah uketumah, because we are no longer concerned that a person will stir the coals. This is known as mitzkameik vera lo.
The Rif and Rambam pasken like the Chachomim, that one may only leave food on the fire if it is mitztameik vera lo, or if the fire is gerufah uketumah. However, the Rosh, followed by the Rema, pasken that it is sufficient to have the food reach maachal ben derusai, and after that point there is no need for gerufah uketumah.
The language of the Rosh is unclear. The Rosh brings opinions that are machmir, and then writes that since Klal Yisroel enjoy oneg Shabbos, we should let them be and follow the more lenient opinion. The Mishnah Berurah understands the Rosh as holding that one should be machmir lechatchilla, and always have the fire gerufah uketumah, but that the Rosh does not want to force it upon Klal Yisroel, especially because they want to have their oneg Shabbos. Thus, according to the Mishnah Berurah, ideally, one should always have a blech.
However, the Chazon Ish disagrees, and paskens lemaaseh that there is no need for gerufah uketumah once the food is past maachal ben derusai. The Chayei Adam follows the same opinion as the Chazon Ish, but the Mishnah Berurah is machmir.
It is important to note that this discussion only applies to shehiyah; regarding chazarah, everyone holds the fire must be gerufah uketumah. We will discuss chazara in later shiurim
Our discussion is relevant regarding leaving food on top of a stove or a crockpot. We will discuss whether it applies to leaving food in an oven in the upcoming shiur, be’ezras Hashem.
- Even when food is not cooked sufficiently to remain on the fire at the onset of Shabbos, one solution to avoid the issur of shehiyah is to make the fire gerufah or ketumah.
- The modern application of ketumah is a blech, which serves to cover the source of heat.
- According to the Mishnah Berurah, even if a food item has reached maachal ben derusai before the onset of Shabbos, it should only be left on the fire if the fire is gerufah uketumah (i.e., has a blech). This is true even if the food is fully cooked, but it is mitztameik veyafeh lo.
If the food has reached maachal ben derusai at the onset of Shabbos, according to the Mishnah Berurah, bedieved it does not require gerufah uketumah. The Chazon Ish holds that lechatchilla it is not required. Preferably, one should follow the opinion of the Mishnah Berurah.