Updated: Apr 18, 2022
A conversation starter
The Beis Yosef teaches the idea that if a maamid was already batul three times, one may go ahead and use it l’chatchila.1 The source for this is found in a Tosefta that permits purchasing sourdough bread from kutim three weeks after Pesach even though they didn’t sell their chometz before Pesach. Since the sourdough starter from the bread made on Pesach was already nullified three times due to their three weekly bakings, it is permitted to purchase their bread.2 So too, the Beis Yosef adduces that kosher milk that was fermented with non-kosher milk is permitted after the fact to use once the non-kosher milk was used to ferment in kosher milk three times.
Some years ago COR was approached to certify an industrial bakery that made sourdough breads. Their family sourdough was always made using their previous breads as a starter. When asked about the source of the original sourdough, they responded with a story. When they came from USSR occupied Poland and started making bread in Canada, they weren’t satisfied with the taste and decided that they needed to get some sourdough from the family bakery back home. In order to get the sourdough, they had to wait until a family member emigrated and brought some live sourdough from which they used to make their breads. Even though the origins of the sourdough weren’t certain, we were able to certify their breads based on the concept that the sourdough had been used more than three times in a kosher recipe and was therefore permitted.
There is much discussion in the poskim that limits the heter of a maamid that was batul three times.3 Mogen Avraham in hilchos Pesach states that if mead from honey was fermented using sediment from chometz beer, then all subsequent fermentation of mead using third and fourth generations of that sediment are forbidden on Pesach.4 Mekor Chaim asks how this conforms to the rule that zeh v’zeh gorem mutar?5 Orech HaShulchan explains that since this fermentation was from a totally chometz source, it remains forbidden forever.6 Only when the fermentation occurs as a dual effort of heter and issur can it be permitted after three times.7
עי’ יד יהודה סימן פ”ז בפה”א ס”ק כ”ו שביאר כן בכוונת הב”י וז”ל “אלא כל דבריו שם להוכיח דבפעם שלישי גם משהו אינו”
2 Beis Yosef (Y.D. 125)
עי’ דגול מרבבה יו”ד קט”ו על הט”ז ס”ק י”ד “עי’ מג”א מ”ש בשם הרמב”ן ואולי שאני חלב עכו”ם שאינו אסור רק מספק”.
4 Mogen Avraham Hilchos Pesach (O.C. 442)
5 Mekor Chaim (O.C.442:6)
6 Aruch HaShulchan (O.C. 442:23)
ונראה דבסימן קט”ו בשאור ובחלב חמוץ, ע”כ נחשב זה וזה גורם משום דפעולת החימוץ היה שייך אף בלי השאור וכן החלב היה יכול להחמיץ גם בלי הוספת החלב חמוץ של הגוים וכן איתא ביד יהודה סימן פ”ז ס”ק כ”ו בפירוש הארוך.