Is it permitted to remove mold from bread on shabbos?

Aside from the issue of Borer, is it also an issue of Tolesh? Ie. Just like removing or picking up a mushroom from the ground is assur(which is a a fungus, and grows on the ground) is considered telisha (Shmiras shabbos kehilchasa 26:10) So too shouldn’t removing the mold from the bread also be considered telisha?

  • Fungus from the ground? I was believing that fungus is not.
    – kouty
    Commented Nov 1, 2017 at 11:12
  • Noted. I fixed it. It grows on ground Commented Nov 1, 2017 at 11:26
  • 3
    @avri no one is forcing you to eat this bread. If it's forbidden then just don't eat it.
    – Double AA
    Commented Nov 1, 2017 at 13:04
  • 1
    I realize that you are asking about the halachic aspects of this. However, see npr.org/sections/thesalt/2017/04/21/523647669/…, which suggests that you should ideally throw away the entire bread. (I won't delve into the halachot of whether you MUST eat bread at all on Shabbat.) At the least, you should cut away a large slice surrounding the visible mold. If you did this, you'd avoid the concern of borer, anyway.
    – DanF
    Commented Nov 1, 2017 at 14:55
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    @DanF and probably do away with the telisha problem as well considering it will still grow on the piece it's left on.
    – user6591
    Commented Nov 1, 2017 at 15:12

3 Answers 3


Rabbi Ribiat in 39 Melachos, Volume 2, page 281, Shemiras Shabbas KeHilchasa 26:10, Rambam Hilchot Shabbat 7:4, 8:3. explain that the Melacha of Kotzer refers to detaching produce from the ground using a utensil such as a sickle.

Tolesh which is the Toldah of Kotzer, includes detaching produce from the ground with one's hands. Uprooting or severing any part of a living plant is forbidden on Shabbat under the category of Kotzer.

There is a discussion amongst the Poskim, if Kotzer applies to things which do not grow from the ground.

Minchas Chinuch Kotzeir 2 asserts that the opinion of Rambam is that Kotzeir is not limited to Gidulei Karka, and this seems to fit with the Gemara Shabbos 107b that pulling a fetus out of its mother’s womb is an act of Okeir Davar M'Gidulo. The Talmud Yerushalmi Shabbos 48b takes this to an extreme and says that pulling a fish out of water is an act of Kotzeir M'Doraisa.

However the Magen Avraham (340:15) seems to imply that Kotzeir only applies to things that grow from the ground. While the Magen Avraham isn't discussing Kotzeir, he does write that all of the Melachos are learned out from the Mishkan and since we hold that dosh is limited to Gidulei Karka, the others must be as well.

Ramban Shabbos 107b also insists that Kotzeir is limited to Gidulei Karka. He rejects the proof from the fetus case, claiming that the Gemara sometimes uses the phrase “Okeir Davar Migidulo” with regards to other Melachos, in this case: Netilas Neshama. He further asserts that the Bavli disagrees with the Yerushalmi about fish. In fact, he suggests that even Rebbi Yehudah who holds that Dosh applies to things that don’t grow from the ground would agree that Kotzeir only applies to Gidulei Karka, since the ground is such an integral part of Meleches Kotzeir.

Based on the above it is clear that at least some authorities will say that there is no Tolesh for something that is not connected to the ground. Even according to the authorities that say that Kotzer / Tolesh applies to things that are not connected I would venture to say that if one removes a piece of the bread together with the mold most likely there would be no issue of Tlisha.

Thanks to http://halachipedia.com/index.php?title=Kotzer for this answer.


In the Halacha Q&A section of the American Yated Ne’eman (28 Cheshvan 5778, Nov. 17, 2017) this exact question was asked to Rav Azriel Auerbach Shlit”a, (The Rav of Bayit V'gan in Jerusalem, and son of Rav Shlomo Zalman Auerbach זצ"ל). What follows is the answer printed there:

Meleches Kotzer involves removing something from its life source (Rambam Shabbos 7:4). While this certainly applies to plucking plants from the ground, it also applies to items that are not attached to the ground, such as picking mushrooms or removing moss from the side of a bucket (Shulchan Aruch 336:5). Although your question is a valid one, removing the mold from the bread does not present a problem of Kotzer. In order to understand this, we must explain a subtle concept in Halacha. Even though scientists may describe mold as growing on the bread, this does not change the Halacha. Chazal considered something to be growing if it grows like a plant, such as wheat, trees, or even the moss you described, even funguses such as mushrooms are considered like growing plants and present an issue of Oker Davar Migidulo. Mold however is not viewed as a growing plant, since it starts off as a microscopic entity, and even when it develops it is not similar to plants or fungus as it spreads and does not consider it to be growing and, therefore we cannot call removing it to be Oker Davar migidulo. However I believe that removing this mold does constitute a problem of meleches borer, because the mold and the bread are two clearly distinct entities. Therefore you should cut off a small part of the bread from under the mold in order to remove it.


The Melocho of Kotzair is defined as the uprooting or severing of a plant from its source of growth. Upon the cutting of the fruit from its tree any potential of future growth is eradicated. Even a Flower attached to its flower pot in your living room is subject to Kotzair as it has the criteria discribed in Masechet Shabbos page 95'which is that its drawing life from its soil.Removing a Fish from the water strips him of his source of life and is therefor according to some considered Kotzair.

Considering a moldy piece of bread,if he took off the mold with a tiny piece of the bread as is required by some authorities in order to evade the Melocho of Borer (according to the understanding that it is not Borer since it is the Derech Achilah of this bread), the moldy part will continue and grow moldier ,and would therefore surely not be considered Tolaish since the mold will continue to grow on that piece of the bread.

However even if he hadn't taken it off with a piece of the bread the mold still contains a tiny particle of the bread (which in itself would not solve the problem of Borer since that tiny speck of bread can not be considered Ochel for it is certainly not edible) which would still continue growing and therefore can not be considered Borer.

Therefore removing the moldy part shall not be considered Tolaish or Kotzair.

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