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The Torah introduces a halachic mechanism in which the minority is nullified in the majority called Bitul. [1]

Introduction to Taste of Forbidden Foods

  1. There’s a dispute between Rashi[2] and Tosfot[3] whether we consider the taste of a forbidden food like the actual forbidden food itself on a biblical level or only on a rabbinic level. Rashi holds it is only rabbinic and Tosfot holds it is biblical. One ramification of this is if there’s a mixture of a forbidden food in a liquid mixture of another taste which was permitted, if it is unclear whether there is sixty times the volume[4] of the forbidden food according to Rashi it is permitted and according to Tosfot it is forbidden. We hold like Tosfot. [5]
  2. A food that fell into a mixture and was nullified and then falls into another mixture that second mixture is also forbidden unless there’s nullification. [6] However, if that item fell back into that same mixture it is still nullified with the original sixty times the forbidden item.[7]
  3. Forbidden foods require sixty times for nullification even if it less than the requisite amount of a kezayit.[8]
  4. Spices which are intrinsically forbidden aren’t nullified in sixty as long as their taste is recognizable. [9]


  1. If the forbidden item in a mixture is recognizable it must be removed. [10]
  2. If the forbidden food is recognizable even if its taste is nullified it must be removed. If the forbidden food isn’t currently recognizable but it is possible to remove the forbidden food nonetheless, one should do so. For example, if forbidden fat was cooked into a mixture but it can be removed by pouring water into it and letting the fat rise one should do so.[11] There is a dispute if one needs to do so if in the process the whole mixture will be ruined. Some poskim advise being strict.[12]

Liquid Mixtures

  1. A forbidden food that fell into a mixture of permitted food that shares its taste is nullified biblically as long as there’s a majority and according to the rabbis requires nullification of one to sixty to be permitted. However, if that forbidden food fell into a mixture of permitted food with a different taste than it, it would require nullification of one to sixty on a biblical level. [13]
    1. For example, meat and fat are considered different types of food unless the meat is very fatty.[14]
  2. Since everything is really dependent on taste, theoretically it would be sufficient to taste the mixture to see if there’s still any taste of the forbidden food in the mixture. However, since it is forbidden to taste, the next option is to give it to a non-Jew to taste. The practice is not to rely on the non-Jew for this matter. In fact there’s a dispute in the poskim whether one can rely on the tasting of an another Jew in cases where it is permitted to taste it and we hold that initially one should not rely on that either.[15]

Bitul BeRov

  1. If non-Kosher solid food is mixed up in a simple majority (51%) of Kosher food, and the non-Kosher food is similar in taste to the non-Kosher piece, is unrecognizable in the mixture, and the mixture is not hot or cooked together, then mixture as a whole is permissible.[16] Nonetheless, one person may only eat the pieces one at a time.[17] Some say that one person shouldn’t eat all of them but rather two or more people should split it up.[18] A stringency would be to take one of the pieces and throw it out or throw it to the dogs.[19]
  2. If the pieces have different tastes[20] in order to have nullification there needs to be sixty times the amount of forbidden food added to the mixture.[21] This applies equally if it is rabbinic prohibition mixed into the mixture of different types.[22]
  3. If the dry mixture which had nullification was later cooked together it becomes forbidden.[23]
  4. When a mixture is permissible because of nullification one person may eat the entire mixture at different intervals and not all at once. It is preferable for one Jew not to eat the entire mixture but rather leave one piece and let another person eat it. It is even more meritorious to be strict to discard one piece or to give it to a non-Jew. [24]
  5. Certain prohibited foods require a higher ratio for nullification. For example, Trumah, Challah, and Bikkurim require a 1 (forbidden) to 100 (permitted) ratio and Orlah and Kelayim require a 1 to 200 ratio. [25]
  6. Some have the practice to boil 3 eggs at a time so that if one is found with a blood spot, it will be nullified and not make the pot non-kosher. Some note that this practice is not necessary nowadays when the eggs are not fertilized.[26]

Bitul BeShishim

  1. If the mixture comprised of either 1) foods of dissimilar taste, 2) liquids, or 3) solids that were hot or cooked together, the nullification required is 1 to 60 called Bitul BeSheshim. [27]
  2. Nullification of 60 means that the volume of permitted ingredients is 60 times the volume of the forbidden ingredients.[28]
  3. If solid foods which were cold and of similar taste are subsequently cooked together the nullification required is Bitul BeShishim.[29] According to Ashkenazim in cases of loss it’s permissible to use the nullification of Bitul BeRov if one knew at first that there was a mixture of non-Kosher and Kosher prior to the mixture being cooked. [30]
  4. If something forbidden was cooked together with permitted food even if the forbidden item is recognizable and is removed, the mixture is forbidden unless the permitted part of the mixture is sixty times the volume of the forbidden part.[31]
  5. Even if it is a rabbinic prohibition or isn't a requisite size of prohibited foods (shiur), sixty times the amount of forbidden ingredients are needed to nullify them.[32]

Awareness of the Nullification

  1. A necessary factor for nullification to take place is that a person must realize that the nullification occurred. However, if a person doesn't realize that the nullification occurred until the situation is further complicated the original nullification is ineffective.[33] Most poskim say that the requirement of awareness is Biblical,[34] while some argue it is only rabbinic.[35]
  2. For example, if one piece of non-Kosher meat was mixed with two Kosher pieces and before he realized that non-Kosher was mixed up with the Kosher pieces he cooked them all together they are all considered non-Kosher. However, if he realized that the non-Kosher was mixed up with the Kosher pieces before it was cooked then nullification occurred and all of them are considered Kosher even if they are then cooked together.[36] Practically, many poskim are strict in this case since the taste of the forbidden piece mixture reawakens the nullified prohibition (Chozer Vneer).[37]
  3. Awareness isn't necessary for the principle of Kol Dparish. That is, if an item is removed from a mixture and considered Kosher based on the majority of the mixture which it came from, it is Kosher even if the person wasn't aware of this until the situation became more complicated.[38] Some poskim disagree and require awareness even for Kol Dparish to be effective.[39]
  4. There is a discussion if the awareness of the nullification of someone other than the owner is effective.[40]

Reawakening Nullified Ingredients

  1. If a forbidden food was nullified because there was sixty times it of permitted ingredients, and then more of the same type of forbidden food fell in, the entire mixture is forbidden unless the combined amount of forbidden food is nullified. This is based on the principle that even forbidden food which was nullified can be reawakened when more forbidden food is added.[41]

What is Included in the Measurement

  1. When measuring the food in a pot to see if it nullified the forbidden ingredients we consider the gravy, scraps of meat, and large pieces of meat.[42] Many poskim hold that dry bones, whether from a permitted or forbidden source, are also counted for nullification. However, the marrow of the bones from a forbidden source is also forbidden. Some poskim argue that bones from a forbidden source can't be counted towards nullification.[43]
  2. The width of the pot doesn't count towards nullification. [44]
  3. We measure the mixture according to the size of the items when they come before the rabbi.[45]

Unsure if there is Sixty

  1. If the food is before us, one must measure it to figure out whether the forbidden item was nullified.[46] Even if it is impossible to measure as long as the forbidden mixture is in front of us, one can't be lenient unless one knows that there was at least sixty times of forbidden taste compared to the permitted taste. [47]
  2. However, if some of the mixture under question was lost or spilled and it is no longer possible to measure whether there was 60 times the prohibited ingredient or not but certainly the majority is permitted, if the mixture is one of similar types it is permitted, however, if it is of dissimilar types it is forbidden. [48]
    1. If there is a mixture of chicken and milk and there's certainly majority of chicken and a minority of milk but it is unclear if there is 60 times the amount of chicken in comparison to the milk or vice versa, and it is currently impossible to measure the mixture because some of it fell or was lost, some poskim are lenient and some are strict. [49]

Foods for which nullification doesn’t work

  1. Spices which were forbidden in it of themselves, such as Orlah, are forbidden even if there's sixty times the amount of permitted food in the mixture.[50]
  2. If the prohibited food will be permitted after a certain time, nullification doesn’t work unless it is mixed with a different type of food (different in name) in which case Bitul BeShishim is effective.[51] Therefore, Chadash grain can not be nullified. [52]
  3. Tevel (produce of Israel wfrom which Trumot and Masserot have not been removed), wine poured to Avoda Zara, and produce of Isreal from the Shemitta (Sabbatical year) can’t be nullified unless it is mixed with a different type of food (different in name) in which case Bitul BeShishim is effective. [53]
  4. Chametz on Pesach and foods use to serve Avoda Zara can not be nullified in any amount. [54]
  5. A complete creature or limb, a piece of meat which is suitable to serve guests, items which are always sold by unit (eggs which are sold by the dozen), and a prominent item (that Chazal specified) can not be nullified. [55] According to Ashkenazim a piece of meat which would be suitable to serve guests after being cooked is not able to be nullified and according to Sephardim only a piece of meat which is suitable to serve guests as of now (meaning, that it is cooked) is not able to be nullified. [56]

Intentional Bitul

  1. It's forbidden to intentionally mix forbidden food into permissible food so that it should become nullified. [57]
    1. If one did so intentionally, the food is forbidden for the person who did the nullification and his family as well as the person on whose behalf it was done and his family.[58] If the person on whose behalf it was done didn't know about it, it is permitted for him.[59]
    2. Others, however, may benefit from the mixture if it wasn't done specifically for their sake. [60]
    3. If one did so unintentionally, because one thought that it was permitted to do so, or because he forgot that the food was forbidden, the nullification is valid and the food is permitted.[61]
  2. If a forbidden ingredient falls into kosher food one may not increase the ratio of kosher food to non-kosher in order to nullify the non-kosher. [62]
  3. A mixture which was permitted because of nullification of majority and one wishes to cook it together which would make it forbidden, one may intentionally add more permitted ingredients so that there would be 60 times the forbidden ingredient before one cooks it and the cooked mixture would be permitted. [63]
  4. Some say that if a rabbinically forbidden item fell into a mixture it is permitted to add more permitted ingredients in order to create nullification. Ashkanzim are stringent not to do so.[64]
    1. Therefore, a person should be careful never to try to use nullification without asking a qualified rabbi.[65]
  5. A person may not ask a non-Jew to perform nullification for him.[66]
  6. Some say that it is forbidden to buy a product which was made with nullification if one can alternatively buy a product which doesn't use nullification. Others say that this is permitted. [67]
  7. If a pot absorbed a tiny amount of forbidden taste and it will always be used for sixty times that amount, it is permitted to use that pot after 24 hours have passed without having it go through a Koshering process. However, if the pot is sometimes used for a small amount of food and the absorbed taste wouldn't be nullified in sixty, it is forbidden to use that pot without Koshering even if one uses with an amount that would actually nullify the absorbed taste. [68]

Absorbed Taste in Utensils

  1. If food was cooked in a pot which was previously used for forbidden food within the same day, the food is forbidden unless the volume of the food is sixty times greater than the volume of the pot. Similarly, if a hot food was mixed with a utensil which absorbed forbidden flavors, the food is forbidden unless the volume of the food is sixty times greater than the volume of the part of the utensil which entered into the food. [69]
  2. If a meat spoon was last used for meat more than 24 hours earlier, then is used for milk that day, and is again used for meat that day, the spoon is considered to have only absorbed up to the volume of the milk that it was used for that day. Some are strict to assume that the spoon absorbed up to the full volume of the spoon if it is made of earthenware. [70]
  3. If a meat spoon was last used for meat with 24 hours, then is used for milk that day, and is again used for meat that day, the spoon is considered to have only absorbed up to the full volume of the spoon. Some are lenient in a case of great loss and the spoon isn’t made of earthenware.[71]
  4. If a forbidden mixture was cooked in a pot and was used after 24 hours passed, the food is kosher but the pot needs to be koshered.[72]
  5. If kosher food was cooked in a non-kosher pot after 24 hours has passed, the spoon used to mix that food while it was on the fire would need to be koshered, however, if that spoon was then used to stir another pot that other food would be kosher and the second pot wouldn't need to be koshered.[73]


  1. This principle is based on the pasuk "אחרי רבים להטת" (Shemot 23:2) meaning that one should follow the majority.
  2. Rashi chullin 98b
  3. Tosfot Chullin 98b s.v. Rava based on the Gemara Pesachim 44b which derives from the pasuk that bread with the taste of wine is biblically forbidden to a nazir.
  4. Badei Hashulchan 98:12 rules that nullification depends on the volume and not weight.
  5. Shulchan Aruch 98:1-2, Badei Hashulchan 98:1
  6. Gemara Chullin 108b, Rama 98:4
  7. Rama 98:4. See Badei Hashulchan 98:61 who explains why we don’t assume that the forbidden taste reawakens when the forbidden item falls in again.
  8. Shulchan Aruch 98:6
  9. Rama 98:8. See Badei Hashulchan 98:84 whether this is biblically forbidden or rabbinically. The Taz holds that this only applies to spices or sharp foods but not everything that has a strong taste. See Badei Hashulchan 98:87 for a variant opinion.
  10. Rama 98:4 writes that if the forbidden item is recognizable it must be removed. He adds that even if the forbidden ingredient has the potential to become recognizable it needs to be removed. For example, if forbidden fat fell into a mixture, one should pour in water to cause the fat to rise and then remove it. Shach 98:16 and Kaf HaChaim 98:57 note that even if the forbidden fat is removed by having it rise to the top still the food is forbidden unless the permitted ingredients are sixty times the forbidden fats. Kaf HaChaim 98:59 quotes a dispute between the Kereti and Pri Megadim whether one needs to do this procedure if it’ll ruin the food and concludes that for a major loss one can be lenient.
  11. Rama 98:4
  12. Badei Hashulchan 98:55
  13. *The gemara Zevachim 78b explains that a mixture of like ingredients is nullified by majority on a biblical level and nullified by one in sixty on a rabbinic level, whereas mixtures of different types are only nullified even on a biblical level if there’s one in sixty. Why do you need 60 needs to nullified the forbidden food in a mixture of like types? The Rosh (Chullin 7:37) explains that it is a particular prohibition to avoid any confusion between these two categories. However, the Rambam (Machalot Asurot 15:4-5) understands that this rabbinic prohibition was such that a forbidden food is never nullified until it is dispersed in such a great quantity such as one in sixty that it is completely lost. The Badei Hashulchan 98:13 cites this dispute.
    • The Rama 98:2 holds that the distinguishing factor between like mixtures and mixtures of different types depends on the type of food and its name. However, the Shach 98:6 argues that the distinguishing factor is the taste of the foods. The Badei Hashulchan 98:19 writes that we hold like the Shach.
  14. Shach 98:1 and Taz 98:1, Badei Hashulchan 98:2
  15. Badei Hashulchan 98:14
  16. The Gemara Chullin 98b assumes that it is possible to nullify a forbidden item in a mixture of permitted ones. Rashi s.v. de’mdeoritta explains that this is based on the pasuk Shemot 23:2 which says that we follow majority. Shach YD 109:6 agrees. See Gemara Chullin 11a which employs that pasuk for the rule of following majority for items that leave a mixture. See also the Shaarei Yosher 3:4 regarding the difference between these concepts. The concept of nullification with a majority is codified by the Tur and Shulchan Aruch YD 109:1.
    • Rambam (Maachalot Asurot 15:4) and Raavad (cited by Ran Chullin 36a s.v. garsinan) hold that even for a dry mixture nullification doesn’t happen with a majority but rather only if there is sixty times the amount of the forbidden item is the mixture permitted. However, the Tosfot (Zevachim 72a), Sefer HaTrumah (Siman 50 s.v. hilkach), Smag (Lavin 140-1), and Rashba (Torat HaBayit 17a) hold that it is permitted even on a rabbinic level with a simple majority. This dispute is discussed in the Bet Yosef YD 109:1. Tur and Shulchan Aruch YD 109:1 hold like the Tosfot.
    • The Pitchei Yeshuva YD 109:1 cites a dispute between the Pri Chadash and Minchat Yakov whether one needs a simple majority of 51% or one needs a ratio of 1:2, or 66.7% of permitted food in the mixture in order to have nullification. He advises being stringent. Kaf Hachaim 109:9 agrees.
  17. The Rosh (Chullin 7:37) writes that bitul makes the asur item turn into heter and one person can eat all 3 pieces of the mixture at once. However, the Rashba in Torat HaBayit (BeDini HaTaarovot p. 17) argues that you can’t eat them at once. When you eat each piece there’s another logic to allow that piece since it could be that the forbidden item was left in the rest of the mixture. Even upon eating the last piece it could be argued that that piece is permitted and the forbidden piece was already eaten. Shulchan Aruch YD 109:1 agrees with the Rashba. The Pri Megadim M”Z 109:1 writes that the Rashba agrees with the Rosh on a biblical level.
    • Interestingly, Shach 109:7 adds that it is permitted to eat two pieces at once and then the last one or vice versa as long as one doesn't eat all three at once. However, the Kaf HaChaim 109:20 and Aruch Hashulchan 109:20 argue that it is forbidden because taking two at once is effectively eating the majority with the forbidden item in it. Additionally, the Shach 109:12 writes that it is equally permitted to cook them in two pots.
  18. Tosfot Rid (b”b 31b s.v. shtei) in fact says it can’t be eaten by one person and doing so would be biblically forbidden. Smag (lavin 141 s.v. shaninu) and Tosfot Chullin 100a s.v. biryah says that two people should eat it.
  19. Rashi Avoda Zara (74a s.v. tarti) holds that in order to allow the mixture one of the pieces needs to be thrown out or thrown to the dogs. However, the Rosh (Avoda Zara 5:30) argues that the only reason that the Mishna Orlah 2:1 one would remove the amount of trumah added to a mixture which nullified the trumah is in order not to steal from the kohanim. Hagahot Sharei Dura (39:6) agrees. The Rama YD 109:1 writes that there is a stringency to be concerned for Rashi and throw out one of the pieces.
  20. Shach YD 109:7 and Pri Chadash 98 s.v. veleinyan assume that differences in taste is critical to consider two foods to be two types unlike the Bach who considers foods to be different if they have a different identification or classification. Shach YD 98:6 argues again at length with the Rama that the critical factor is taste and not identification.
  21. The Tur YD 109:1 postulates that there’s no difference whether the pieces in the mixture are of the same types of different types. However, he also cites the Sefer HaTrumah who says that if there’s different types there is a need of sixty times the forbidden amount in order to have nullification. The Bet Yosef YD 109:1 cites the Ran (Chullin 36b, end of Perek Gid HaNasheh) who says that it is forbidden unless there is sixty times the amount of forbidden food in the mixture. His reasoning is that since if the mixture were to be cooked together the need for having sixty for nullification would be biblical, there is a rabbinic need for sixty for nullification even though it is a dry mixture. The Hagahot Shaarei Dura 39 holds that this is biblically forbidden, while the Iser Veheter 26:11 holds it is only rabbinically forbidden. The Shach 109:10 cites the Maharshal, Torat Chatat 39:4, Ran (Chullin 36b), and Rashba (Chullin 97b s.v. ubekedeirah) who side with the Iser Veheter. Shulchan Aruch YD 109:1 (according to the Shach 109:2) and Rama ad loc. hold like the Sefer HaTrumah and require sixty for nullification of a dry mixture when there’s two different types in the mixture.
  22. The Shach 109:9 concludes based on the Ran that if there’s a dry mixture of different types with only a rabbinic prohibition mixed in it is nullified with a majority. The Rama 109:1 seems to equate the cases whether it was a rabbinically prohibited or biblically prohibited item that it should require sixty times for nullification of different types. The Gra 109:8 agrees.
  23. The Rashba (Torat HaBayit 17a, responsa 1:272) holds that once the mixture is cooked together it is forbidden even though it is a mixture of one type since once it is cooked together the entire mixture shares the taste of the forbidden food. This is also the opinion of the Ran (Chullin 36a s.v. garsinan). The Rosh (Chullin 7:37) and Smak (Siman 214) argue that it is permitted even if it was cooked together. Shulchan Aruch YD 109:2 rules like the Rashba, while the Rama adds that in a case of a major loss one may rely on the Rosh.
  24. S”A YD 109:1, The Laws of Kashrus (Rabbi Binyamin Forst; pg 54-6)
  25. Rambam Machalot Assurot 15:13-4
  26. Halachically Speaking vol 4 issue 18
  27. S”A and Rama 109:1-2, The Laws of Kashrus (Rabbi Binyamin Forst; pg 58-61)
    • According to Rabbi Yehuda (Menachot 22a) a mixture of items of a similar type aren't nullified, however, according to the Rabbis it is. Rashi (Chullin 109a s.v. VeTu) holds like Rabbi Yehuda. Tosfot (Chullin 97a s.v. amar rava), however, argues with Rashi and rules that we hold like the Rabbis. Ran (Chullin 34b), Rosh (Avoda Zara 5:29), and Rambam (Maachalot Asurot 15:6) agree with Tosfot. Tur and Shulchan Aruch YD 98:2 hold like the Rabbis that a mixture of similar items is nullified.
    • Rava in gemara Chullin 97a states that one can rely on the testimony of a non-Jewish chef that a mixture of meat and a bit of milk doesn't have any dairy taste in it to permit it to a Jew. Concludes the gemara, if there no chef around or it is a mixture of similar items and it is impossible to taste the forbidden item specifically, one needs nullification of 60. (a) Rashi (Chullin 98a s.v. beshishim) implies that even if there's no taste of the forbidden ingredient still the mixture is forbidden unless there is also nullification of 60. (b) Similarly, the Ramban Chullin 98a s.v. kol holds that if the forbidden food dissolved into the permitted food it is nullified with 60 and not the taste of a chef. Yet, if the forbidden food was removed from the mixture but its taste remains it is nullified with the taste of a chef even if that's less than 60. (c) However, the Tosfot Chullin 99a s.v. elah and Rosh (Chullin 7:29) argue that if the non-Jew doesn't taste the forbidden ingredient it is permitted even if there isn't nullification of 60. (d) The Bet Yosef YD 98:1 understands that the Rambam (Machalot Asurot 15) thinks if there's an option to ask a non-Jewish chef one should and if he says that there's a forbidden taste, it is forbidden even if there's nullification of 60 and if he says that there's no forbidden taste it is permitted even if there's not nullification of 60.
    • Shulchan Aruch YD 98:1 holds like the Rambam. However, the Rama 98:1 based on the Agur writes that the minhag Ashkenazim is not to rely on a non-Jew to taste for a forbidden taste and just always use nullification of 60. The Kaf HaChaim 98:2 records that the Sephardic minhag was also to always use nullification of 60.
    • While the Shach 109:5 writes that we can rely on the taste of a Jew when it is permitted for the Jew to taste it, the Kaf HaChaim 109:12 quotes the Chavot Daat 109:2 who disagrees.
  28. Pitchei Teshuva 109:2 writes that when evaluating nullification volume is measured and not weight. Kaf HaChaim 109:5 agrees.
  29. Shulchan Aruch YD 109:2 based on the Rashba (Torat HaBayit 17a)
  30. Rama 109:2 based on the Rosh, however, Kaf HaChaim 109:40 writes that Sephardim don’t hold of this leniency.
  31. Based on the Gemara Chullin 97b, Rashba in Torat HaBayit holds that whenever a forbidden item is cooked into a mixture and then is removed, the amount of flavor that emanated from it could be as large as the actual item itself. He holds this regarding all types of prohibited food even rabbinic prohibitions. This is opposition to the opinion of the Orchot Chaim (Maachalot Asurot no. 13) and Raavad (Tamim Deyim no. 7) who distinguish between different types of prohibitions. Shulchan Aruch YD 98:4 rules like the Rashba. Shach 98:10 and Kaf HaChaim 98:44 adds the stipulation that applies even to rabbinic prohibitions.
  32. While the Rambam (Maachalot Asurot 15:17) holds that all rabbinic prohibitions are nullified with fifty nine times the amount of the forbidden ingredients, the Bet Yosef 98:8 writes that the majority of poskim disagree and Rama YD 98:8 writes that sixty times is necessary. Kaf HaChaim 98:73 agrees. The Gemara Chullin 98a states that if a forbidden food is less than the requisite size of the prohibited food (shiur), it still requires sixty times for nullification. This is codified by Shulchan Aruch YD 98:6.
  33. Mishna Trumot 5:8, Rosh Chullin 7:37
  34. The Shach 109:12 writes that without an awareness of the mixture Biblically there isn't nullification. Pri Chadash 109:10 agrees. Chachmat Adam 51:18 and Kaf Hachaim 109:45 agree with the Shach and disproves the Minchat Yaakov.
  35. Minchat Yaakov 39:18
  36. Rama 109:2
  37. Shulchan Aruch YD 109:2 is strict. Kaf Hachaim 109:40 agrees even if there's great loss. Rama is lenient in cases of great loss.
  38. Binyamin Zeev (Kuntres Acharon n. 14), Rav Poalim YD 1:23 s.v. Vachar, Chazon Ish 37:20. Minchat Pittim (Rav Meir Arik YD 8) writes that Kol Dparish doesn't require awareness for it to be effective. He proves it from the Ran Chullin 33b s.v. amar. Darkei Teshuva 110:59 cites the Minchat Pittim.
  39. Binat Adam Bet Hakavuah n. 13
  40. Yerushalmi Orlah 2:1 seems to in doubt about awareness of a friend if that's effective. Darkei Teshuva 109:65 quotes the Levushei Sharad 109:25 who holds that nullification is only effective if the owner knew. He also quotes Yad Elimelech 5 who holds that for a rabbinic prohibition awareness of someone else is effective.
  41. Rama 99:6 rules like the Rosh who says that even if all the ingredients are dry, even if they're all of the same type, and even if one knew about the nullification before the second forbidden food fell in, still the old forbidden food is reawakened and forbidden. The Shach 99:21 argues that if there's no concern of taste being transferred such as where the ingredients are dry, of the same type, and one knew about the nullification before the next piece of forbidden food fell in one can be lenient to assume that the old forbidden food is reawakened. Kaf HaChaim 99:70 and The Laws of Kashrut (p. 68) follow the Rama against the Shach.
  42. Shulchan Aruch YD 99:4
  43. Shulchan Aruch 99:1 rules like the Rashba (Torat HaBayit 6a) that even the forbidden bones count towards nullification, but the Rama cites the Or Zaruah who holds that the forbidden bones can't be considered towards nullification and adds that in cases of loss one can rely on the Rashba. Kaf HaChaim 99:11 writes that Sephardim primarily follow Shulchan Aruch here. The Shach 99:1 and Kaf HaChaim 99:2 are strict regarding moist bones from a forbidden source to include them in the measurement of the forbidden ingredients.
  44. Tur and Shulchan Aruch YD 99:1
  45. Shulchan Aruch YD 99:4
  46. Orchot Chaim (Machalot Asurot n. 14 s.v. hareviyi) quoting the Rabbenu Peretz, Bet Yosef 98:2
  47. Shulchan Aruch YD 98:3 writes that only if a mixture is before us one must measure it, however, if it was spilled and one doesn't know how much was in the mixture and whether that was sufficient to nullify the forbidden taste that's considered a doubt. The Taz 98:6 quotes the Mordechai who explains that if a fool can't measure it but it is possible for other people to measure that's not considered a doubt since it is possible to ask someone else to measure it. However, if no one in the generation knows how to measure it that's considered a valid doubt. The Shach 98:9 similarly quotes the Mordechai but also quotes the Ran who says that as long as the mixture is before us it isn't considered as though there's a doubt if there's nullification as the Rabbis made an enactment without distinctions. The Kaf HaChaim 98:43 cites the Shach and notes that it seems that the Taz's leniency, that if no one knows how to measure it, it is considered a doubt even if the mixture is before us, is against the Ran.
    • As an outgrowth of this discussion, if a non-Jew or child added forbidden food to a pot and one can't know how much forbidden ingredients were added, the Pitchei Teshuva 98:8 quotes the Emunat Shmuel who believes that it is considered like the case of the food spilling or getting lost since it is nearly impossible to figure out the measurement. Nonetheless, the Emunat Shmuel writes that his logic was speculative and not definitive for a ruling. The Pri Chadash 98:9 agrees with the Emunat Shmuel even as definitive ruling. Chachmat Adam 51:13 and Badei HaShulchan 98:17 hold like the Pri Chadash that the addition of forbidden food by a child or non-Jew in a case where it is impossible to measure the amount of forbidden food that was added is considered a valid doubt.
  48. Rashba (Torat HaBayit 11b), Tur and Shulchan Aruch YD 98:2. The logic of the Rashba is that he follows Rabbenu Tam (Tosfot Chullin 98b s.v. rava) who says that in a liquid mixture of different types the need for nullification is biblical and since there is a doubt about a biblical prohibition one should be strict. The general principle is that when dealing with doubts about a biblical prohibition one should be strict. However, he states a mixture of like types biblically is nullified with majority and only rabbinically needs nullification of 60 and so if one is in doubt one can be lenient. This is also the opinion of the Rosh (as cited by the Tur 98:3). It is noteworthy to mention that the opinion of Rashi (Chullin 98b s.v. letaam) and the Rambam (Machalot Asurot 15:2-3, as understood by the Bet Yosef YD 98:2; responsa of the Rambam Pear Hadur 65) is that even a liquid mixture of different types is biblically nullified with majority only needs nullification of 60 rabbinically. Shulchan Aruch YD 98:2 follows the Rashba.
  49. According to the Shach 98:7 it is permitted based on the logic of the Rashba that we should say since there is only a rabbinic prohibition and there's certainly nullification on a biblical level we can be lenient. However, the Taz 98:5 argue that it is forbidden since we treat chicken and milk like meat and milk for all intents and purposes even though it is rabbinic. Pitchei Teshuva 98:6 cites the Emunat Shmuel and Pri Chadash as agreeing.
  50. Rama YD 98:8. Shach 98:29 quotes the Iser Veheter who says that this is only rabbinic. Taz 98:11 holds that the idea of the Rama that something added for taste can't be nullified only applies to sharp tasting foods such as spices. Taz also states that if the spices are only forbidden because of the mixture, such as meat and milk, they can be nullified and only if they are forbidden in it of itself can't they be nullified.
  51. Gemara Beitzah 3b, Rambam (Hilchot Maachalot Asurot 15:10), S”A YD 102:1
  52. The Laws of Kashrus (Rabbi Binaymin Forst; pg 62)
  53. Rambam Machalot Assurot 15:6, 8
  54. S”A OC 447, S”A YD 140
  55. Shulchan Aruch YD 100, 101, S’A and Rama 110:1
  56. S”A and Rama 101:3, Taz 101:5
  57. Gemara Beitzah 4a, Shulchan Aruch YD 99:5. The Raavad (Isur Mashehu ch. 2) considers this to be Biblically forbidden, while the Ran (Chullin 35b) and Rashba (Torat HaBayit 31b) hold that it is derabbanan. See Bet Yosef Y"D 99, Shach 99:7, and Chachmat Adam 52:6
  58. The Yerushalmi Orlah 3:6 states that if a person did nullify a prohibited item, if done so intentionally it is forbidden if unintentionally it is permitted. This is echoed in the opinions of Rabbi Shimon and Rabbi Yose in Gittin 54b. The Rambam (Maachalot Asurot 15:25, according to the Bet Yosef 99:5), Rashba (Torat HaBayit 31b), and Tur 99:5 codify this as the halacha. Shulchan Aruch YD 99:5 concurs. The Rashba (Torat HaBayit 32a) writes that the food is forbidden for the person doing the nullification as well as the one for whom it was does on his behalf so that he doesn't benefit from his sinful actions. The Rashba cites the Rambam and Raavad in agreement with this idea. Shulchan Aruch YD 99:5 codifies this. Additionally, the Maharshal cited by the Taz 99:10 writes that anytime it is forbidden for the person it is also forbidden for his whole family. The Kaf HaChaim 99:45 agrees. See Kaf HaChaim 99:46 regarding the dispute whether the penalty against one who did nullification includes the pot as well.
  59. Taz 99:10, Kaf HaChaim 99:44
  60. Shulchan Aruch YD 99:5
  61. Shulchan Aruch YD 99:5 writes that if the nullification happened unintentionally the food is permitted. See previous footnote for his sources. The Taz 99:7 states that if a person thought it was permitted to do so, it is considered as though he was unintentional. Kaf HaChaim 99:38 and The Laws of Kashrut (p. 75) agree. The Kaf HaChaim 99:41 writes that if a person forgot that it was forbidden that too is considered unintentional.
  62. Shulchan Aruch Y"D 99:5
  63. Shulchan Aruch YD 109:2 based on the Raah. The Taz 109:3 and Shach 109:13 explain that the logic for this is that since the mixture is currently permitted it is permitted to add as much as one wishes even though it is preventing an forbidden item from prohibiting the mixture later upon cooking it.
  64. Shulchan Aruch YD 99:6 permits adding to a mixture with a rabbinically forbidden item in order to permit it with nullification. This is based on the Gemara Beitzah 4b. The Rama, however, argues that it is forbidden to do so. See Shulchan Aruch OC 677:4 who seems to forbid as well. Kaf HaChaim 99:68 writes that the Sephardi minhag is to follow Shulchan Aruch and allow nullification on derabbanan prohibitions by adding to the mixture.
  65. The Laws of Kashrut (p. 75). See Pitchei Teshuva 99:5 regarding a person who asked an unqualified rabbi and he ruled incorrectly that it is considered intentional. See, however, Kaf HaChaim 99:39.
  66. Radvaz 3:547 says that it is forbidden to ask a non-Jew to do nullification and if one did so, the food is prohibited. He adds that if the non-Jew did nullification without the Jew asking even if he recognizes the jew it is permitted unlike a non-Jew who does melacha for a Jew on Shabbat. The Kaf HaChaim 99:50-51 quotes the Radvaz.
  67. Kaf HaChaim 99:52 cites the Radvaz who is strict against the Erech HaShulchan who is lenient. The Badei HaShulchan 99:38 is lenient.
  68. The Gemara Avoda Zara 33a states that a container a non-Jew used for wine can be used for a Jew to drink water. The Rashba (Torat HaBayit 36b) explains that since only a tiny bit of the wine taste was absorbed into the containers and it will be nullified when later used to drink water it is permitted. The Rivash (no. 349) and Raavad (cited by Ran Avoda Zara 12b) agree.
    • The Raah (Bedek HaBayit 36b) vehemently argues with the Rashba because it should be considered a violation of intentionally nullifying the forbidden absorption in the pots. Rather he explains that the absorption of wine in the containers that the Gemara was discussing is minimal since it is all cold. Also, the wine taste is ruined when it mixes into the water and that isn't considered intentional nullification. The Maadanei Asher (Isur V'heter Siman 81) explains that the Rashba would respond that it isn't forbidden because of intentional nullification unless it is possible that there wouldn't be nullification but if there certainly is nullification, it is permitted.
    • The Tur (YD 122) also disagrees with the Rashba but for another reason. He says if the rabbis enacted a decree against using a pot with forbidden taste if 24 hours passed and now the absorptions are permitted, how much more so would they enact a decree against using a pot with absorptions within 24 hours just because it'll be nullified lest one use it for less than the amount that would cause nullification. The Bet Yosef YD 122:5 answers that there's no decree on something uncommon and it is uncommon to use a pot of such a size for a quantity of food less than sixty times the forbidden absorption.
    • The Taz 99:15 discusses this Rashba at length and offers two alternate explanations of the Gemara Avoda Zara 33b. Based on Rashi, the water is permitted since it dilutes the wine absorption and ruins it. Additionally, the Ran (Avoda Zara 12b) explains that it is permitted to fill up the wine containers used by the non-Jews for wine in order to Kosher them and even though in the process the water will nullify the wine absorption it is permitted since that isn't one's intent. The Taz concludes in disagreement with the Rashba.
    • The Shulchan Aruch YD 99:7 rules like the Rashba and the Kaf Hachaim 99:73 and Aruch Hashulchan 99:49 write that one can rely on the Rashba only if 24 hours have passed.
  69. Shulchan Aruch YD 98:4.
    • Rabbenu Peretz (cited by Tur YD 98:4) held that if a metal utensil is partially inside the hot food the entire utensil becomes hot and imparts taste to the food, however, the Tur disagrees. Rama YD 98:4 rules like the Tur. Kaf HaChaim 98:56 writes that one should be strict for Rabbenu Peretz unless there is a large loss.
    • Kaf HaChaim 98:48 explains that when discussing food cooked in a forbidden pot we always consider as though the entire pot imparted forbidden taste even if the food only cooked in half of the pot since there is hot moisture which spreads the forbidden taste throughout the pot.
  70. Shulchan Aruch YD 98:5 and Rama, see next note.
  71. The Rashba (Torat HaBayit 1b) writes that if a new spoon was used for a prohibited food or a meat spoon was last used for meat more than 24 hours earlier and is then used for milk that day, then it is considered to only have absorbed the taste of the amount of milk it was used for. However, if it was used for meat within 24 hours, then is used for milk and again for meat, then we consider the spoon to having absorbed the forbidden taste up to the full volume of the spoon. He cites the Ramban as holding that a utensil never becomes completely forbidden and only ever receives the amount of forbidden taste it absorbed even if that was within 24 hours. The Bet Yosef 98:5 understands that the Tur follows the Rashba, while the Ran follows the Ramban. Shulchan Aruch YD 98:5 and Rama rule like Rashba. Kaf HaChaim 98:65 agrees. Shach 98:21 rules that in cases of great loss one can rely on the opinion of the Ramban.
    • The Taz 98:8 understands the Mordechai cited by the Rama to say that if an earthenware spoon is used it becomes forbidden up to the full volume of the spoon even if was only used for a certain amount. He concludes that one should be strict for the Mordechai.
  72. Rama 103:2. The Badei Hashulchan 103:28 cites the Gra who explains the reason is that the rabbis forbade using this pot for something for which it will taste good and forbid it.
  73. Badei Hashulchan 103:38