For halachic questions of Kashrut a person should consult a rabbi because the laws of Kashrut involve many complexities.
The biblical Prohibition
- Take note that we are only speaking in terms of the Torah prohibition here. There are many cases where it is rabbinically forbidden to have meat and milk even though there is no biblical prohibition. For example, it is Rabbinically forbidden to eat milk and meat together even if they were not cooked together.
- The Torah states three times “לֹא-תְבַשֵּׁל גְּדִי בַּחֲלֵב אִמּוֹ” “You shall not cook a kid (baby goat) in its mother’s milk”[1]. Our Sages learn that the repetition of this prohibition three times informs us the prohibitions of cooking, eating, and having any type of benefit (monetary or feeding one’s animals) from milk cooked with meat.[2]
- Our Sages teach us that the language of “לא תבשל”-“You shall not cook” implies that the Biblical prohibitions only apply if the meat and milk are cooked together.[3]
- There is discussion whether frying or roasting meat and milk together is included in the biblical prohibition.[4] There is also discussion about if it is forbidden biblically to cook meat and milk together in a pot that is hot (Yad Soledet Bo), but is no longer on the fire.[5]
- There is a discussion if microwaving meat and milk together is considered cooking meat and milk together.[6]
- If you mix milk and meat in a kli sheni (a pot that was never on the fire), even if it is hot, you do not biblically violate cooking meat and milk.[7]
- If a mixture of meat and milk is not biblically prohibited then one may derive benefit from it so long as one doesn’t eat it.[8]
- The Torah only refers to a “גדי”; however, our Sages have taught us that a “kid” refers to all kosher domesticated animals (e.g. sheep, cows). We were also taught that all types of kosher animal milk are prohibited to cook meat with, not only the milk of the mother. Rather, the reason why the Torah was so specific is because it was speaking in the present (i.e. that the verse spoke in terms which are similar to the way the world functioned at the time).[9]
Cooking and Benefitting from Milk and Meat
- There is a biblical prohibition to eat or benefit from meat and milk cooked together. Additionally, cooking meat and milk together is itself a biblical prohibition. [10]
- For example, it is forbidden to use butter cooked in a meat pot as a candle for light or for Chanuka candles since that would be benefitting from milk and meat.[11]
- This biblical prohibition only applies to milk and meat from kosher species. Therefore, it is permitted to cook and benefit from the mixture of milk and ham or meat from another non-kosher species. Similarly, it is permitted to cook or benefit from the mixture of pig milk or milk from another non-kosher species with meat.[12]
- However, it is forbidden to cook or benefit from meat from an unslaughtered animal and milk or meat from an animal that was Tereifah and milk. [13]
- It is forbidden to eat chicken cooked with milk, however, it is permitted to cook and benefit from chicken and milk.[14]
- Even if one isn’t going to eat the food, it is forbidden to cook meat in a dairy pot that was used within the last 24 hours for dairy.[15]
- It is forbidden to stoke the coals under a pot that is cooking meat and milk.[16]
- According to many poskim it is permitted to smell meat and milk together such as a cheese burger since they are cooked as food and not for the smell.[17]
- Can you sell a utensil which has absorptions of meat and milk? Some poskim say that it is permitted since one isn’t directly benefiting from the absorptions as much as the actual pot. Others hold that one should only sell it after 24 hours.[18]
Feeding An Animal Meat and Milk
- Some hold that it is forbidden to feed meat and milk cooked together to animals, even ones that belong to other people, since there is a benefit in having one’s desires fulfilled and by using the meat and milk one was able to fulfill his intentions.[19]
Cold Meat and Dairy Touching
Dry Foods Touching
- Initially it is forbidden to have meat touch cheese if it is uncommon to wash the meat and cheese before eating them because one might forget to wash them before eating them.[20]
- If a cold piece of cheese or dairy food touched a cold piece of meat or a meat food, the area of their contact each needs to be washed before being eaten.[21]
- If both foods were dry and don’t make crumbs then they don’t even require washing and it all depends on what you see.[22]
- When washing the area of contact the food should be washed in water and rubbed gently to clean it from anything being stuck onto it.[23] If a dairy food was cut with a knife with meat fat the dairy food needs to be washed and rubbed well.[24]
- After the fact if the dairy and meat foods touched and were cooked separately without being washed beforehand, some say that it is kosher[25] while others are concerned unless there is certainty that there was 60x the crumbs that transferred.[26]
Liquid and Solid Touching
- If a cold piece of cooked meat fell into liquid milk according to Sephardim the meat should be washed and it is permitted, while according to Ashkenazim the meat is forbidden up to the depth of a peel and the milk is permitted.[27]
Utensils
Cups and Glasses
- One shouldn’t drink from the same cup when one was eating meat and when one is eating dairy[28] unless one cleans the cup in between in which case it is totally permitted.[29]
- One can use the same cup to drink a parve drink while one is eating meat or milk as long as one wipes one’s lips before drinking so that a fat residue doesn’t stick to the lip of the cup.[30]
- Some say that there’s a minhag to have separate dairy and meat drinking cups.[31] Others argue that one can use the same glasses for milk and meat meals as long as they are washed in between. They can be used for cold or hot parve drinks.[32]
- It is permitted to use a cold drinking glass in a non-kosher restaurant for a cold drink. But one should only have a hot drink in a disposable cup.[33]
Knives
- One shouldn’t use a knife that was used to cut a dairy food to cut bread that one is planning to eat with meat. The same is true of the opposite case. The reason is because we’re worried that a knife in general has a bit of fat stuck onto it.[34]
- One shouldn’t use a knife that was used to cut a meat food to cut a dairy food or the opposite.[35]
- Some have the practice to have a parve bread knife that is designated to cut bread so that the leftover bread can be eaten without a concern of mixing meat and milk.[36]
Tablecloths
- If a person ate meat on a tablecloth he should change the tablecloth before eating milk. The same is true vice versa.[37]
- Some poskim are lenient that one doesn’t need to change the tablecloth between meat and milk since nowadays we eat on plates.[38] Others are strict.[39]
Salt Bowls
- One shouldn’t leave an open bowl or cup with salt next to[40] a dairy liquidy food[41] since accidentally some of the dairy might splatter into the salt and later one might use that salt for meat.[42]
Salt Shakers
- It is recommended to have two salt shakers since the shakers might touch food or residue on people’s hands might get on the shaker.[43]
Pots
- If a person cooked parve food in a meat pot and then dairy food was cooked in that pot within 24 hours of the meat the dairy food is considered non-kosher and the pot needs to be koshered.[44]
Pot Covers
Hot Cover on Hot Pot
- If one uses a meat pot cover to cover a milk pot while it is on the fire or the opposite, the food, pot, and the cover are non-kosher.[45]
- If the pot is currently cooking parve and the pot or the cover weren’t used within 24 hours, the food would be kosher and the utensil which was used within 24 hours remains kosher, but the one which wasn’t used within 24 hours is non-kosher. If both weren’t used within 24 hours the food, the pot and the cover are kosher.[46]
- If the food in the pot is meat then that makes the pot and the cover absorb taste of meat immediately even if it wasn’t used within 24 hours for other meat. The same is true of milk.[47]
- The same is true whether or not the cover was hot as long as the pot was hot.[48]
- Some say that we can’t assume a pot cover that we’re unsure if it was used within 24 hours that is considered eino ben yomo.[49]
Hot Cover on Cold Pot
- If one accidentally placed a hot cover on a cold pot, some say that the food, the pot and the cover are all still kosher.[50] Other poskim hold that the pot needs to be koshered.[51] Poskim are strict unless there is financial loss involved.[52]
- The above only applies when the hot lid was wet or moist, but if it was totally dry then everything is kosher.[53] Without any more information we have to assume that a hot lid that was on a cooking pot and removed is still moist.[54]
Cold Cover on Hot Pot
- If someone accidentally places a cold cover on a hot pot, and it was left there for a while it is treated like we treat a hot cover on a hot pot, described above.[55]
Chumra of Non-Ben Yomo Lids
- In the Ashkenazi rishonim[56] there was a minhag to be strict on all lids to treat them as though they are ben yomo even if they are certainly eino ben yomo. Some try to provide justification for the minhag but ultimately it is a difficult minhag to explain.[57] Although the Rama 93:1 tried to abolish the minhag,[58] nonetheless, in his notes to Shulchan Aruch he writes that some have this minhag. He adds that if there are any other factors to be lenient in this case one can be lenient so as not to add to this minhag which is difficult to begin with.
- The Maharshal (Chullin 8:46:7) explains that the chumra (stringency) only applies to cover pots with a section that are hard to clean and so there could be actual food frosted on the inside of the lid that can’t be cleaned and therefore it could forbid the food even when it is not ben yomo since food doesn’t spoil by sitting out for 24 hours. Therefore, if one can be sure that the lid doesn’t have any area that is hard to clean or had enough in the pot to nullify the food that could be stuck to that section of the cover the food is kosher. This approach is adopted by the overwhelming majority of poskim.[59] It follows that for the common modern pot covers this isn’t an issue.[60]
- Sephardim don’t have this minhag.[61]
- According to the chumra, some say it that if one cooked parve in a ben yomo meat pot and covered it with a eino ben yomo dairy cover or the opposite, the food should be eaten with meat since it is meat equipment[62] but regarding the pot cover some say that it is forbidden,[63] while others are lenient.[64]
- It doesn’t apply to anything besides a designated cover and not if you put a pot on top of another pot.[65]
- Some say that after two months certainly the pot lids have the status of eino ben yomo.[66]
- If there is an area that is hard to clean and we assume that there’s some food that collected there, some say that it is necessary to have 60 times that area to nullify it, while others say you need slightly less than 3660 times that area to nullify it.[67]
Refrigerators
- It is permitted to leave meat and milk foods in the refrigerator without designating an area or shelf for meat or milk. However, one should be careful to make sure not to leave something that could spill or leak such as a milk carton over a meat food.[68]
Food that was on the Table
Stovetops
- Some poskim suggest being strict to use separate grates for stovetops that are designated for meat or dairy, however, many other poskim aren’t concerned and permit using the same grates.[69]
Drop of Milk on Meat in Pot
- If a drop of milk falls into the liquid part of a soup or stew it is nullified in that soup if the food in the pot is sixty times the drop’s volume.[70]
- If a drop of milk falls onto a piece of meat that is partially submerged in the liquid of a soup or stew it makes that piece forbidden unless there is sixty times its volume in that piece. However, with respect to the rest of the food in the pot it wouldn’t forbid it unless there wasn’t sixty times the drop’s volume in all of the food of the pot.[71]
- If a drop of milk falls onto a piece of meat that is completely out of the liquid part of the soup or stew that piece would be forbidden unless there is sixty times its volume in that piece.[72] According to many poskim the rest of the food in the pot would be kosher.[73]
Drop of Milk on Outside of Pot
- If there’s a drop of milk that splashed on a meat pot on the fire that is cooking, if the drop falls on a spot that corresponds to the area where the food is cooking that drop of milk is nullified in sixty times the contents of the pot. [74]
- However, if the drop falls on a spot that is above the area where the food is cooking the top of the pot becoming non-kosher and then the food in turn is non-kosher unless there is 3600[75] in the contents of the pot to nullify the drop.[76]
- The only time that 3600 is necessary is if the pot was used within 24 hours for meat and then the drop fell on the outside of the pot above the line where it is was cooking on the inside of the pot meat. However, if it wasn’t used in 24 hours for meat then only sixty is necessary.[77]
- In all of the above cases even if the food is kosher the pot needs to be koshered.[78] In a case of need, Sephardim are lenient if the milk fell on the outside below the line where the food was cooking.[79] The pot should be koshered on the inside and outside.[80]
Meat and Dairy Equipment (Nat Bar Nat)
Parve Food Cooked with Meat or Dairy Equipment
- Parve food cooked in a meat pot according to Ashkenazim should not be eaten together with dairy, but after the fact if it was cooked with dairy it would be permitted to be eaten. According to Sephardim it is permitted even initially to eat the parve food made with meat equipment with dairy.[81]
- Parve food cooked in a dairy pot according to Ashkenazim should not be eaten together with meat, but after the fact if it was cooked with meat it would be permitted to be eaten. According to Sephardim it is permitted even initially to eat the parve food made with dairy equipment with meat.[82] Some even permit cooking the parve food in the meat pot to eat it with dairy.[83]
- If the meat pot wasn’t used within 24 hours for meat, then if something parve cooks in it, the parve food can be eaten together with dairy even initially. However, one shouldn’t use a meat pot even if it hasn’t been used within 24 hours to cook parve food that one intends to eat with dairy. The same is true of dairy and meat vice versa.[84] According to Sephardim all cases of cooking parve food in a meat pot in order to eat it together with dairy are permitted.[85]
- Parve food cooked in a meat pot can be eaten with dairy utensils but the parve food shouldn’t be poured directly from the meat pot onto a dairy utensil. The same is true of the opposite case.[86] It is permitted to even initially indirectly pour (Iruy Shenifsak Hakiluach) the food into the dairy utensil from a meat pot.[87]
- It is permitted to reheat food made with dairy equipment in a meat pot.[88]
- According to Ashkenazim and some Sephardim one shouldn’t cook the parve in a meat pot in order to eat it with dairy or vice versa. After the fact even if one intentionally made the food in a meat pot in order to eat with dairy most poskim hold that it is nonetheless permitted to eat with dairy.[89]
- Tasting transferring from food to food isn’t considered nat bar nat. Nat bar nat needs to involve a utensil.[90] If there is a transfer from food to utensil to food that is nat bar nat. From utensil to food to food or food to food to utensil are questionably nat bar nat.[91]
Roasting, Baking, Soaking
- Some Ashkenazim are more strict if the parve food is roasted or baked as opposed to cooked in a dairy equipment to treat it like dairy food, while others consider it like the general category of dairy equipment. This has ramifications even after the fact if that parve food is mixed with meat. The same is true of parve food roasted or baked with meat equipment.[92] Most poskim hold that roasting is no different than cooking.[93]
- If the parve food soaked in a meat or dairy pot there is an unresolved discussion if that would render the food meat or dairy equipment.[94]
Dairy Spoon Used to Mix Meat Pot Cooking Meat
- If a dairy spoon was used to mix a meat pot with meat in it, if there isn’t sixty in the pot relative to the amount of the spoon that was inserted into the food, the spoon, the food, and the pot are rendered non-kosher. If there is sixty in the pot the food and pot are kosher but the spoon is rendered non-kosher.[95] Alternatively, if the spoon wasn’t used for dairy within 24 hours the food and pot are kosher but the spoon is rendered non-kosher.[96]
Dairy Spoon Used to Mix Meat Pot Cooking Parve
- If someone used a dairy pot, used for dairy within 24 hours, to cook parve and stirred it with a meat spoon, used for meat within 24 hours, the pot, the food, and the spoon are forbidden according to Ashkenazim.[97]
- If the dairy pot and the meat spoon weren’t used within 24 hours for their respective kind then they have no effect upon each other.[98] Nonetheless it is best to eat the food parve not with meat or milk.[99]
- If the dairy pot or the meat spoon weren’t used within 24 hours for their respective kind then they have no effect upon each other. However, the minhag is to treat the food like the one that wasn’t used within 24 and the utensil that wasn’t used within 24 hours as non-kosher.[100]
- If a dairy spoon was used to mix a parve soup or food with liquids in a meat pot, according to Ashkenazim the food and the pot are rendered non-kosher. If there is sixty times the spoon in the soup the food and pot are kosher and the dairy spoon is rendered non-kosher. If the dairy spoon wasn’t used within 24 hours the food and pot are kosher and the spoon is rendered non-kosher. According to Sephardim the food, pot, and spoon are kosher.[101]
- If a dairy spoon was used to mix rice, noodles, or vegetables in a meat pot on the stove where there aren’t liquids between the foods, some poskim hold that for Ashkenazim the food, the spoon, and the pot are rendered non-kosher. Others hold that only the food is non-kosher, while still others hold that everything remains kosher.[102] Sephardim hold like that everything remains kosher.[103]
Dairy or Meat Spoon Used in Parve Pot
- If a person used a dairy spoon to mix parve food in a parve pot then we should treat that pot like it is dairy. The same is true if a person used a meat spoon to mix parve food in a parve pot.[104]
- If a person used a dairy spoon to mix parve food in a parve pot rendering the pot dairy and then a meat spoon was used to mix parve food in that same pot, that pot shouldn’t be used at all.[105] Some are lenient to say to treat the pot as meat.[106] After the fact if a person used that pot the food isn’t forbidden.[107]
- If the parve food in the pot was sixty times the spoons then they have no effect on the pot.[108] Additionally, if the spoons were not used within 24 hours for meat or milk they have no effect on the pot.[109]
Transference of Taste
See the complete topic here: Transferring Taste
If there’s no liquids
- If a hot meat pot touches a hot dairy pot and there’s no liquid in between the pots the two pots are still kosher because taste doesn’t transfer between pots without liquid.[110]
- If a hot piece of meat touches a hot piece of dairy and there’s no liquid between the pieces and neither piece is fatty only a finger-width of each piece surrounding where they touched is made non-kosher. Ashkenazim are strict to forbidden the entire piece of meat and dairy.[111]
- If a hot piece of fatty meat touches a hot piece of dairy and there’s no liquid between the pieces the entire piece is forbidden since the fat spreads taste.[112]
- A piece of meat which absorbed a dairy taste is considered completely forbidden. Therefore, if it is hot and touches a piece of kosher food it will cause that other food to become non-kosher up to the depth of a finger-width.[113]
- If you mix rice with milk or butter and the milk or butter is completely absorbed and then the rice is mixed with a meat spoon the rice is non-kosher but the spoon and pot are kosher, some however hold that the rice, spoon and pot aren’t kosher.[114]
If there are liquids
- If hot or even cold meat fell into hot milk or vice versa everything is forbidden. [115]
- If hot milk falls onto cold meat the meat is only forbidden up to the depth of a peel. Sephardim hold that the milk is permitted, while Ashkenazim hold that the milk is forbidden unless there is sixty times the area of contact to the depth of a peel.[116]
- One shouldn’t pour water from a faucet or parve cup into a hot meat pan since the stream will affect the faucet making it meat like the pan, otherwise the faucet or parve cup will become meat. The same is true with a milk pan.[117]
Pouring
- If hot meat from a kli rishon fell into cold milk or hot milk from a kli rishon fell onto cold meat the meat needs to have a klipah removed and the milk is permitted.[118]
- If the klipah wasn’t removed and it was cooked after the fact the it is permitted but if the klipah is recognizable it needs to be removed.[119]
- If a cooked[120] piece of hot meat from a kli rishon fell into a cold dairy salty liquid[121] if it was raw it could be washed off. If it was cooked it would be forbidden up to the level of a klipah. If it was spiced or has cracks it would be entirely forbidden. According to Ashkenazim even cold meat that fell into a cold dairy salty liquid is forbidden up to a klipah. If it has cracks or is spiced it is entirely forbidden.[122]
Kli Sheni
- If a hot piece of meat is cut with a cold dairy knife if the knife was used for dairy within 24 hours the amount of a “peel” needs to be removed from the meat. If it wasn’t used within 24 hours the meat is kosher. The knife in either case needs to be cleaned off but not koshered.[123] However, many poskim hold that the meat is completely not kosher and the knife needs to be koshered.[124]
- This applies even if the meat isn’t yad soledet bo as long as it is hot.[125]
Kashrut of Ovens for Meat and Milk
- To avoid all issues one should choose the primary use of the oven for meat or milk and then cover the other type. For example, if he chooses that it be used as a meat oven, the meat foods can be cooked in there uncovered. The dairy dishes with liquid should be covered, however, the dry dairy dishes can be cooked uncovered. Also, if within 24 hours of cooking a meat dish with liquid one wants to cook a dairy dish with liquid one should wait until after 24 hours even if it is covered.[126] Some Ashkenazic poskim permit using an oven for meat and milk consecutively as long as there are no spills or residue on the oven walls or floor.[127]
- According to Sephardim, many Poskim rule that nowadays a person should have separate ovens for cooking meat and for cooking milk.[128] In cases where this is difficult, one can be lenient to use one oven so long as one covers all food placed in the oven. Alternatively, if one cooks a solid food in the oven over 24 hours apart from of the opposite type and one also preheated it for 20 minutes.[129] After the fact, one may be lenient.[130]
- According to some, if the foods are dry foods that don’t produce vapors, then one may place the foods in the oven one after the other (but not at the same time).[131] Others rule that one should wait 24 hours between cooking the foods and that one should first let the oven run for 15 minutes before placing the second food into the oven.[132]
- In a case where someone has only one oven, he does not need to have separate oven grates for meat and milk.[133]
Zeyia
- The primary reason that cooking in an oven could transfer taste from the food to the walls or the opposite is through the mechanism of zeyia, steam, or more accurately defined water vapor. Generally, the poskim hold that the zeyia of a food that is cooking contains the taste of the food and transfers its taste.[134]
- Some poskim hold that there is no issue of zeyia in an open area[137] but most poskim disagree.[138] Therefore, it is advisable not to pour salt from a saltshaker into an open pot cooking on the fire since the zeyia from that food will get absorbed in the saltshaker. If that happens if the food is meat then the salt becomes meat and if the food was dairy then the salt becomes dairy.[139]
- Some poskim considered the possibility that zeyia doesn’t get into a food that is itself steaming. It certainly isn’t accepted but some poskim use it as a factor.[140] Others disregard this idea.[141]
- Some poskim hold that solid foods do not have any zeyia and only liquids have zeyia.[142] Many poskim disagree.[143]
- A minority opinion holds that zeyia is burnt up in an oven[144] but isn’t accepted.[145]
- A minority opinion holds that zeyia dissipates in an oven that has a small vent.[146]
- Zeyia which isn’t yad soledet bo can’t transfer taste.[147] Therefore, if meat is hanging above a pot of dairy that is cooking if it is so high above the pot that the steam isn’t Yad Soledet Bo there is no concern.[148]
- A covered pot can’t transfer zeyia.[149]
Reycha
- If one cooks two foods in the oven at the same time there is a smell (trans. reycha; Heb. ריחא) that is transferred from one food to the other. After the fact, the food is permitted.[150]
- There are some instances where it is possible for reycha to forbid food even after the fact according to Ashkenazim:
- If the oven is small and completely sealed reycha forbids the food even after the fact.
- If one of the foods is a Dvar Charif then reycha can forbid the food even after the fact.
- If the prohibition under consideration is forbidden in any amount, such as chametz, reycha can forbid the food even after the fact.[151]
How to Prevent Reycha
- There is no reycha when foods are cooked one after another.[152]
- If the oven is large enough to hold 12 isaron of bread and has a large vent there is no reycha. The poskim assume that our ovens today do not have that requisite size.[153]
- If one or both of the foods were in pots with walls those walls separate between them and prevent reycha from transferring from one to the other.[154]
Reycha for Parve
- Bread: If one cooked open meat simultaneously with open bread in the oven at a temperature above Yad Soledet Bo one shouldn’t eat the bread with dairy.[155] Ashkenazim are lenient if one doesn’t have other bread available.[156]
- If a person cooked parve bread in the oven at the same time as he cooked a dairy bread it is best to treat the parve bread as dairy.[157]
Microwave for Meat and Milk
- If one uses a microwave for meat and for dairy (at different times), some authorities hold that one should preferably double wrap all foods[158], however, some authorities hold that covering it well with one covering is sufficient. Some also advise using different trays one for dairy and one for meat. [159]
- Alternatively, one can cover all dairy foods with one large plastic microwave container and all meat foods with another container designated for meat. Also, the plastic containers may have tiny holes to let out steam.[160]
- If one wasn’t careful to keep his microwave kosher in these regards, one can make it kosher again by cleaning the microwave out and boiling water in the microwave for a few minutes until it steams. Some also recommend adding soap to the water that is to be boiled in the microwave.[161]
Toaster-Oven for Meat and Milk
- One should preferably designate his or her toaster-oven specifically for meat or for dairy, since it is small and hard to clean out. The concern is that small particles remain behind in the toaster-oven and would then make it impossible to separate between meat and dairy foods.[162]
Steam Jacket Kettle
- Some permit using a steam jacket kettle even if that steam was previously used for non-Kosher.[163]
Washing Meat and Milk Dishes in One Sink
- Ideally, one should have two sinks one for meat and one for milk.[164]
- It is permissible to wash meat and dairy dishes in a sink one after another as long as there are two boards or racks to raise the dishes off of the bottom of the sink, one for meat and one for dairy.[165]
- Hot water poured from a kli rishon can cause flavors to be imparted up to the depth of a peel.[166] Therefore, if hot water from the sink hits a piece of meat and then a piece of dairy it would be impart flavor up to the depth of a peel in the dairy food.[167] There is a dispute if the hot water from the sink hit a piece of meat and then a dairy pot if it would impart flavor up the depth of a peel in the pot.[168]
- One should certainly not clean dirty meat and dairy dishes together in one sink. After the fact some poskim hold that the dishes are fine,[169] while most assume that this would cause the meat and dairy dishes to become non-kosher.[170] For Ashkenazim, the halacha is that one should not wash dishes together in the sink at the same time and if one did, even if the dishes were clean beforehand they should be koshered. [171]
- After the fact, if there were no pieces of meat, dairy, or even grease on the dishes and they were washed together in the same sink the dishes are all kosher.[172] Some are strict and hold that even if the dishes had no pieces of meat or dairy on them nonetheless washing them together under a hot faucet would cause them to become non-kosher.[173]
- After the fact, if the meat dish had a piece of meat on it or even just grease and the dairy dish was clean, and they were washed together in the sink, both dishes are considered non-kosher. In a case of a large loss some say that the meat dish would be considered kosher, while the dairy would be considered non-kosher. The same is true of the opposite case.[174]
- Hot water which was poured and the stream was broken is considered hot enough to impart flavor up to the depth of a peel but can’t transfer taste from one food to another. [175]
- If one is cleaning meat dishes in the same sink in which one cleaned milk dishes, if there’s still some dairy remnant in the sink, it’s forbidden to pour hot water there because at the time one pours the water the meat and milk are halachically cooked together even though one has no intention of using those remnants. [176] Some say that technically, it is permitted but best to avoid.[177]
Dishwashers
- According to Ashkenazim, some say that it is forbidden to use a dishwasher for meat and milk even one after the other and even if one uses different racks. [178] Sephardim only allow using one dishwasher for meat and milk if they are used in different shifts and the dishes are first rinsed to remove the large pieces.[179]
- If there is porcelain in the walls of a dishwasher it can’t be koshered. If it is metal then it can be koshered but not the plastic parts.[180] There is a dispute if the hard plastic racks can be koshered.[181]
Accidental Placement of Wrong Type in Sink
- If one accidentally placed a utensil of the wrong type in the sink and it was cold everything should be washed with cold water and is permitted. If the utensil was hot but was placed there with only parve food in the utensil then it is permitted, especially if the area between the utensil and sink was dry but it is permitted even if it was wet.[182]
Soaking as a Form of Cooking
- Milk and meat that were soaked together for 24 hours or were salted together may not be eaten, however, they are permitted to benefit from.[183]
- If a prohibited item was soaking together with a permitted item in a liquid for 24 hours the permitted item is. If it was there for less than 24 hours it is sufficient to just wash off the permitted item. [184] The definition of liquid for this purpose is something that jiggles when a person moves the container.[185]
- If it soaked for 24 hours non-consecutively, such for 23 hours and then for another hour, after the fact most poskim assume that it is permitted.[186]
- If a prohibited item was soaking in a pot for 24 hours, the pot absorbed the prohibited taste and would need to be koshered.[187] There is a discussion if metal and glass pots absorb taste through soaking.[188]
- If a permitted item was soaking in a non-kosher pot for 24 hours, after the fact the food is kosher according to most opinions, yet a person should only be lenient in cases of great loss. [189]
Inedible Foods
- Prohibited food which is inedible is permitted on a biblical level[190] and forbidden on a rabbinic level because when your eating the food indicates that it is good.[191]
- Medicines made with prohibited ingredients which were made inedible, some poskim permit this since one’s intent isn’t to eat the prohibited item, while others are strict.[192]
Negative Taste (Noten Taam Lifgam)
- If a forbidden item fell into a mixture and adds a negative taste, if the actual forbidden item was removed the mixture is permitted.[193]
- If a forbidden item fell into a mixture and adds a negative taste, if the actual forbidden item dissolved completely and there is greater detriment from the negative taste than the increase of volume, the mixture is permitted.[194]
- There is a dispute whether or not this leniency of spoiled tastes applies to chametz on pesach. [195]
- Noten taam lifgam applies to all prohibitions including combinations of milk and meat.[196]
Sharp Foods
- If an onion or another sharp food is cut with a meat or milk knife or is cooked in a meat or milk pot see the Sharp Foods page.
Taken from: Milk and Meat in the Kitchen – Halachipedia