Source: https://www.halachipedia.com/index.php?title=General_overview_of_Kashrut
Timestamp: 2019-04-25 08:24:07+00:00

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It’s forbidden to eat the taste of non-Kosher food which was absorbed into another food.
If someone finds a blood spot in an egg today should be strict to throw it out.
Cows which have their stomachs punctured for gas build up might not be considered teref and as such the Shochet doesn't need to check for it, however, if he sees that it has scares from those punctures it isn't kosher.
Many poskim hold that it is permitted to use soaps made from animal fats even if they included the forbidden fats.
See Kosher Wine: Yayin Nesech, Stam Yeinam, and Maga Akum for details.
A person who ate fish should wash out his mouth with a solid and liquid before eating meat. Ashkenazim hold that one doesn't have to wash one's hands but Sephardim hold that one should also wash one's hand before eating meat after having fish.
It is permitted to cook fish in a meat pot even if it is was used within that same day.
Fish in meat is nullified one in sixty even though it is a concern of danger.
Some hold that it is permitted even initially to add more to the mixture in order to nullify the danger of meat and fish and that there would be sixty times.
There is a Sephardic custom not to eat fish and dairy together.  Such is the Syrian practice. Ashkenazim hold that it is permitted.
Ashkenazim hold that it is permitted to have fish and dairy together.
One may not eat food that was cooked by a non-Jew. See the Bishul Akum page.
Many poskim hold that it is permissible to own stock in a company that sells meat and milk cooked together such as McDonald's.
Many poskim permit eating veal with a reliable hechsher. The issues involved are that there is a greater percentage of terefot, the animals aren't treated nicely, and the diet consists of meat and milk.
The fact that there is a higher percent of terefot doesn't exclude the ability of a shochet to check the lungs to determine if it is kosher. The kashrut organizations checked that there isn't a higher concern of a teref developing in the intestines of the calf when raised as veal.
Since the calves are fattened with a meat and milk formula there is an issue of eating an animal that was fattened with something that's forbidden in benefit (nitfatma biusrei hanah). There are several factors to permit the meat nonetheless. First, not all rishonim agree that the halacha forbids an animal that was fattened with something that's forbidden to benefit from. Second, since the meat is non-kosher some rishonim hold that the meat and milk combination is not forbidden to benefit from. Third, perhaps the diet of the veal is comprised of other permitted ingredients and the forbidden benefit is only considered one factor but not the sole contributor (zeh vzeh gorem). Forth, the meat and milk were individually cooked before being cooked together in which case it might not be considered a meat and milk combination that is forbidden to benefit from. The kashrut organizations have tried to mitigate this issue by using a kli sheni to create the formula and not kli rishon, which would also not create a meat and milk combination that is forbidden.
See this topic discussed on OU.org and in the Journal of Contemporary Halacha.
Although some poskim argued that royal jelly should be considered kosher, most poskim hold that it is not kosher.
↑ The Gemara Avoda Zara 66b discusses whether a smell ('reyacha') is halachically significant. The Rashba Teshuva 3:234 writes that for anything that isn't made to give off a smell even if it is forbidden for benefit such as Orlah or Kilayim it is permitted to smell. Tosfot Avoda Zara 12b s.v. elah disagrees. Shulchan Aruch Y.D. 108:6 rules like the Rashba, while Shach 108:27 sides with the Tosfot. Rabbi Shmuel Pinchasi on dailyhalacha.com follows Shulchan Aruch. See Or Tzadikim 12:59 who writes that one shouldn't smell non-kosher food since one might come to eat it.
↑ The gemara Keritut 21b says that eating human blood is only derabbanan once it separated from the body. The gemara explains that if a person is eating and finds blood on the piece of food that is forbidden, however, if a person’s teeth are bleeding that blood is permitted and a person can swallow it. Rambam (Machalot Asurot 6:2) and Shulchan Aruch YD 66:10 codify this halacha. Rama YD 66:10 adds that if human blood fell into a food and isn't recognizable it doesn't forbid the mixture. The Pri Megadim S"D 66:16 writes that theoretically this is the case even if the human blood is in the majority.
↑ Igrot Moshe OC 3:61 writes that although the majority aren't fertilized at all and there is no issue so the blood could be removed and the rest eaten but since eggs are so cheap it is right ot be strict and throw it all out.
↑ The Mishna Chullin 42a enumerate 18 defects and the Rambam Hilchot Shechitah 10:9 counts 70.
↑ Rav Ovadia Yosef (Taharat Habayit v. 3 p. 244) quotes the Tosfot niddah 32a and many other rishonim that smearing forbidden animal fat on one's skin isn't forbidden because it is like eating. Additionally, he quotes the Pri Chadash YD 177:4 who says that the soaps are unfit for eating and as such there's no issue of using soaps. The Aruch Hashulchan YD 117:29 agrees. See however, Biur Halacha s.v. 326:10.
↑ Shulchan Aruch YD 116:2, Yalkut Yosef YD 87:83, Kitzur Shulchan Aruch 33:1. See Dr. Fred Rosner's article in Tradition v. 35 pp. 36-44 about the theory that it is unhealthy since there's small bones in fish and a person might swallow one without realizing if he is also eating meat at the same time which doesn't have small bones. However, he questions that theory and concludes that we don't have a scientific explanation of this danger today.
↑ Shulchan Aruch YD 116:3 based on the practice of the Rosh that one should wash one's hands and mouth before eating meat after having fish. However, the Rama says that practice isn't to wash one's hands or mouth before having meat but it is proper to wash out one's mouth with a solid and liquid.
The Magen Avraham 173:1 and Chatom Sofer YD 101 question whether this prohibition should really still apply today since it doesn't seem to be dangerous. Kaf Hachaim 173:9 says that since this is a question of health one should be strict.
↑ Shach (Nekudat Hakesef YD 116:2) holds that fish in meat is nullified one in sixty. Taz 116::2 understands that the Maharil holds that it isn't nullified at all. Yabia Omer YD 1:7:10 quotes the Chatom Sofer 101, Rogachover in Safnat Paneach 264, Zer Zahav 39:7, Sheilat Shalom 2:165, Bet Shlomo 2:218, Olat Yitzchak 146, and Sh"t Maharitz Chiyitz 52 who agree with the Shach. Yabia Omer also agrees with the Shach.
↑ Pitchei Teshuva YD 116:3 writes that it is permitted to even initially nullify something that is a concern of danger. Yabia Omer YD 1:8:7 quotes Rav Yitzchak Elchanan in Ayin Yitzchak OC 24:2, Maharash Engel 1:83, Chamudei Doniel 96a, and Divrei Shalom Vemet OC 13 who agree. However, he also quotes the Tuv Taam Vdaat 3:2:10 and Anei Tzedek YD 49 who hold that it is forbidden to initially nullify something that is a concern of danger. Yabia Omer is lenient.
↑ Bet Yosef 87:3, Yalkut Yosef YD 87:84, Yechave Daat 6:48, BI"H, Beha'alotecha, 15, Kaf Hachaim 87:24, Horah Brurah 87:13. Rabbenu Bechay Shemot 23:19 explains that it is spiritually dangerous to eat fish and cheese because milk is derived from blood which causes the one who eats it to become cruel and when that mixes with fish which causes the one who eats it to become lazy together they are negative for a person's soul. He concludes that fish and cheese causes bad middot and tzarat. See Darkei Teshuva 116:43.
↑ Shulchan Aruch YD 117 writes that it is forbidden to sell non-kosher food. Gilyon Maharsha 117:1 forbids even investing in a non-kosher business even though there's no concern that one will come to eat the non-kosher food. Kaf Hachaim 117:69 quotes most achronim who are strict about investing in a non-kosher business but some who are lenient. Igrot Moshe EH 1:7 allows buying shares of a publically traded company that works on Shabbat since he doesn't mean to buy any share of the actual company and its tools but just to invest in the value of the corporation. He allows that as long as one isn't invested so heavily that he is involved in the voting or management. Similarly, Rav Dovid Feinstein (cited by Journal of Halacha and Contemporary Society v. 24 p. 85) ruled that it is permitted to own stock in McDonald's since one is just an investor and not like one is actually doing business with the non-kosher food. Halachically Speaking v. 4 Issue 21 p. 7 discusses this as well.
↑ Igrot Moshe EH 4:92 was strict that the intestines should be checked in calves raised for veal. Rav Aaron Tietelbaum is cited by the RJJ v. 45 p. 8 fnt. 5(by Rabbi Josh Flug and Rabbi Ezra Schwartz) that the kashrut organizations checked and didn't find a higher incident of a concern.
↑ Rama YD 60:1 based on Avoda Zara 49a. Kaf Hachaim 60:12 is strict.
↑ RJJ article cites Mesorah v. 15 pp. 74-8 who suggests that it is zeh vzeh gorem because of the water that the calves drink. RJJ Article p. 17 clarifies that the kosher ingredients in the formula aren't considered zeh vzeh gorem because of chaticha naaseh nevelah. Pri Chadash 47:9 is lenient on any zeh vzeh gorem where the animal itself is considered a gorem together with the food, but his opinion is disputed by Kanfei Yonah YD 60. Also, Bet Hillel 60:1 based on Tosfot A"Z 48b s.v. vrabbanan writes that the animal isn't considered one of the factors as a gorem.
↑ Pri Megadim OC 673:1 writes that there's no bishul achar bishul of meat and milk if they were already cooked together but if they were cooked separately it is still forbidden to cook them together. Yalkut Yosef Isur Vheter v. 3 p. 190 writes that it is possible to question this.
↑ Pri Megadim SD 87:19 writes that cooking meat and milk together in a kli sheni isn't considered cooking and the result would be permitted to benefit from. Yalkut Yosef Isur Vheter v. 3 p. 111 agrees.
This page was last edited on 12 March 2019, at 18:01.

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