1) HALACHAH: A FORBIDDEN FOOD ITEM THAT RUINS ONE MIXTURE, BUT WHICH IS BENEFICIAL FOR ANOTHER
OPINIONS: The Gemara discusses the argument between Rebbi Meir and Rebbi Shimon whether or not a forbidden item which is "Nosen Ta'am li'Fegam" forbids a mixture into which it falls. Rebbi Yochanan (arguing with Ula) states that the Tana'im argue in a case in which the forbidden item in the mixture gave a bad taste to the mixture immediately upon falling into it.
Rav Amram says that proof for Rebbi Yochanan's statement can be found in the Mishnah in Orlah (2:9). The Mishnah discusses a case in which a leavening agent of Chulin which fell into a pot of dough and affected the dough, causing the dough to start to rise, and then a leavening agent of Terumah or Kil'ei ha'Kerem -- which also had the ability to affect the dough -- fell into the dough. The Tana Kama there (presumably Rebbi Meir) says that the mixture is forbidden, while Rebbi Shimon says that it is permitted. RASHI (DH v'Rebbi Shimon) explains that Rebbi Shimon says that the dough is permitted because adding extra leavening agents (in this case, of Terumah or Kil'ayim) makes the dough worse, not better. This, Rav Amram says, proves Rebbi Yochanan's point that the argument between Rebbi Meir and Rebbi Shimon applies even when the bad taste enters the mixture immediately. Rebbi Zeira refutes the proof, saying that the case in Orlah is not comparable to a prohibited item with a bad taste. There, the prohibited item is bad only for this dough (which already contains a leavening agent), but it is good for other batches of dough (which do not yet contain a leavening agent), and that is why, in that case, the leavening agent of Terumah prohibits the mixture immediately.
Is Rebbi Zeira's answer, and its ramifications, considered the Halachah?
(a) The RAMBAM (Hilchos Ma'achalos Asuros 16:16) says that the Halachah follows the Tana Kama, and that such a mixture is forbidden. The RADVAZ (ibid.) explains that although the Rambam rules that, in general, "Nosen Ta'am li'Fegam" is permitted, this case is different, as Rebbi Zeira says. Accordingly, we can infer that the Rambam would forbid any mixture with an agent of Isur which improves food, even though the Isur, in this mixture, is bad or inedible.
This logic is also applied by the RAN in Pesachim (45b). The Gemara there states that bread which rotted to the point that it is no longer fit for human consumption is still forbidden to possess on Pesach. The Ran explains that even though things which are not fit for consumption should no longer be forbidden (as the Gemara here says earlier), rotted bread can still be used as a leavening agent and thus is not considered totally unfit. This is evidenced by the Torah's explicit prohibition of leaven (Se'or) in Shemos (12:19), even though leaven is not fit to be eaten. It must be that its potential usefulness in creating Chametz makes it forbidden.
This has many practical applications. For example, the Poskim discuss whether or not lemon powder (for cooking) made with glucose syrup extracted from wheat may be considered kosher for Pesach. RAV BENTZION ABA SHAUL in OR L'TZION (OC 1:34:3) writes that the fact that the lemon powder is inedible before it is mixed into food does not make it lose its previous status of Chametz. He quotes the CHAVOS DA'AS (Yoreh De'ah, Biurim 103:1) who cites the aforementioned Ran and states explicitly that anything that is used to help another food cook or bake is forbidden, even though it itself is inedible. This is also the opinion of the PRI MEGADIM in MISHBETZOS ZAHAV (OC 447:1, regarding a piece of old Chametz Nuksheh that was hard and inedible for many years that falls into a pot) and ACHIEZER (YD 11:2-3).
Although RAV OVADYAH YOSEF (in YECHAVEH DA'AS 2:62) agrees that one should not use products with such lemon powder on Pesach (even if bought before Pesach), he permits it b'Di'eved.
(b) However, the NODA BI'YEHUDAH (YD 1:26) suggests that the Rambam actually holds, contrary to most other Poskim, that a mixture with "Nosen Ta'am li'Fegam" is forbidden. He also states that any Isur which became hard and inedible, and then it softened and became edible again, loses its prior status and is permitted (see SHEVET HA'LEVI OC 1:152:1). Accordingly, the Rambam mentioned above would not write that he rules in accordance with Rebbi Zeira's explanation, since he rules that the leavening agent of Terumah is forbidden because it is a case of "Nosen Ta'am li'Fegam." (Y. MONTROSE)
2) "NOSEN TA'AM LI'FEGAM" IN A CASE OF A "SHERETZ"
QUESTION: The Gemara relates an incident in which a mouse fell into a barrel of beer. Rav rules that the beer in the barrel is now prohibited. Even though Rav maintains that, in normal cases, a mixture with "Nosen Ta'am li'Fegam" is permitted, he rules that such a mixture is prohibited when the Isur involves an Isur of Sheratzim. This is because the Torah forbids eating Sheratzim even though they always have a bad taste and are "Nosen Ta'am li'Fegam," and people regard them as disgusting things to eat. This shows that they are always forbidden, even though they are "Nosen Ta'am li'Fegam."
Rava later in the Gemara argues with this and rules that even in the case of a mixture containing a Sheretz, the mixture is permitted because of "Nosen Ta'am li'Fegam." Why does Rava ignore Rav's logic to prohibit Sheratzim in a mixture?
(a) We can understand Rava's opinion based on the words of the RASHBA in TORAS HA'BAYIS (4:1). He explains that when determining whether or not a mixture containing a forbidden food is permitted, we judge by whether or not the forbidden food gives a taste to the mixture. In order to be considered present in the mixture because of its taste, the forbidden food must provide a good taste. If it provides a bad taste to the mixture, then it is considered something that spoils the dish and is not considered a "taste." Accordingly, when there is an unidentifiable Isur in a mixture which increases the mass of the food substantially, but which detracts from the taste, the mixture is still permitted. (See Insights to 67b, where we cite the CHAVOS DA'AS (YD 103:1) and RAV CHAIM SOLOVEITCHIK (Hilchos Ma'achalos Asuros 15:1) who explain that the Rashba's reasoning is based on the source of the principle of "Ta'am k'Ikar.")
This answers our question. Although Sheratzim are always disgusting and are inherently "Nosen Ta'am li'Fegam" and the Torah still forbids them, this does not mean that we should alter the basic logic from the source for the principle of "Ta'am k'Ikar" because of this exception. Rather, a Sheretz still must give a good taste to the mixture in order to prohibit it.
(b) However, the RAN (67b) explains that the laws of "Nosen Ta'am li'Fegam" are derived from the laws of Neveilah. Neveilah is forbidden when the person eating it will enjoy the Isur as long as it is edible, even if it is slightly ruined. However, if it is deemed inedible, it is permitted to be eaten even though it was originally a forbidden piece of meat. Similarly, in the case of a mixture in which an Isur gives a bad taste to a permitted food, the person eating it has no pleasure at all from the Isur in the mixture, just as he has no pleasure from a totally spoiled piece of Neveilah, which is permitted. According to the Ran, therefore, our question remains. If a person who eats a Sheretz does not have any benefit from it, and yet the Torah still forbids it, then a piece of Sheretz in a mixture which is "Nosen Ta'am li'Fegam" should also forbid the mixture!
We may suggest that the Isur of Sheratzim is a novel Isur that differs from the normal laws that apply to other prohibitions of eating. All other prohibited items can at least be called "food," while Sheratzim cannot be called "food" and are entirely inedible. It is possible that even the Ran understands that items like Neveilah can be represented by their tastes because there is some benefit derived when eating a tasty Neveilah as opposed to eating a spoiled one. However, with regard to Sheratzim, the Torah forbids the act of eating the actual Sheretz without regard to its taste, since a Sheretz does not have a taste. Since the taste of a Sheretz is not related to its prohibition, Rava permits a mixture in which the Sheretz is no longer identifiable, even though its [bad] taste is noticeable in the mixture (see also KEHILOS YAKOV 25:7 and YOSEF DA'AS here). (Y. MONTROSE)