Gemara

66a (Mishnah): If (forbidden) spices of two or three names from the same species, or from three different species, were mixed together, they join to forbid the food.

69a (Rav Tachlifa bar Giza): Perhaps a mouse is considered like spices of Terumah in a pot. They are not Batel in 100 times their volume.

Chulin 6a (Mishnah): One need not tithe a mixture containing Demai (Safek Tevel).

Contradiction (Beraisa): One who gives his neighbor a dough to bake or a pot to cook, he need not worry that she leavened or spiced it with Se'or ((sourdough, which is used to ferment) or spices of Tevel or Shemitah produce. If he told her to use her Se'or or spices, he must be concerned.

Answer (Rafram): Se'or and spices are different. They are added for their taste, so they are not Batel.

99a (Mishnah): If Terumah beans were cooked with Chulin lentils, if the beans gave taste to the lentils, whether or not there is 101 (times as much as the beans), the lentils must be eaten like Terumah. If the beans didn't give taste, whether or not there is 101, the lentils are like Chulin.

99b (Reisha): If Se'or of (Terumah) wheat fell into a dough of wheat, and it is large enough to ferment it, or there is not 101 times as much as the Se'or, we must treat the dough like Terumah.

Question: When the Se'or can ferment the dough, why don't 101 parts of dough Mevatel it?

Answer (Abaye): Perhaps Se'or is more stringent, because it is a potent fermenting agent.

Support (Rav Dimi): R. Yosi bar Chanina taugh that the quantities needed to be Mevatel different foods varies. Fish brine requires 192 parts of Heter. (R. Yehudah says so in a Mishnah.)

Rishonim

Hagahos Ashri (Avodah Zarah 5:6): Spices are added for taste, and taste is not Batel. I.e. we do not say that whenever there is 100 times as much Heter they are Batel, but surely they can be Batel (if one cannot taste them).

Tosfos (69a DH k'Tavlin): Spices and peppers are not Batel in 60 or 100, for a small amount gives much taste to a big pot. Do not say that they are never Batel, for they were taught among things that forbid due to taste, and not with things that forbid any amount. Above (66a) we said that spices join to forbid.

Tosfos (108b DH Amai): Rav (108a) said that if a K'Zayis of meat fell into a cauldron of milk, the meat is forbidden, but the milk is permitted. The Gemara said that this is correct if the meat does not forbid the milk itself. Even though milk is absorbed in the meat (and absorbs form the meat) and is emitted, since the milk is Asur only due to the meat it absorbed, it forbids only based on the amount of meat absorbed. This shows that if spices absorbed Chelev or blood and fell into a pot, they are Batel in 60, even though they give taste to the entire pot, for they are no more stringent than the Isur they absorbed.

Poskim

Rema (YD 98:8): All Isurim that apply nowadays are Batel in 60, except for Chametz on Pesach and Yayin Nesech. However, if the Isur gives taste to the pot, and the Isur is Asur due to itself, it is not Batel even in 1000, as long as one can taste it. Therefore, salt and spices, which are added for taste, if they are forbidden due to themselves, they are not Batel in 60.

Suggestion (Beis Yosef YD 112 DH Pas): Since Se'or mixes with the dough, even if it were Asur due to bread of Nochrim, one could use it to ferment bread. This is because Chachamim did not decree about a mixture of bread of Nochrim. Any amount of Isur that ferments forbids (Mishnah Orlah 2:4).This stringency is only for Isurei Torah, but not for Isurei mid'Rabanan, and all the more so it is not for bread of Nochrim, which is more lenient.

Rejection (Beis Yosef): In Chulin, we challenged the opinion that Chachamim did not decree about a mixture of Demai from a Beraisa. Rafram answered that we are concerned for spices of Tevel or Shemitah because they are added for their taste, and taste is not Batel. The concern for Tevel is mid'Rabanan, yet we are concerned for Se'or and spices. Rather, the decree was only on bread of Nochrim, but not on their dough or Se'or. Therefore, one may buy Se'or of Nochrim to ferment.

Beis Yosef (Sof 105 DH Kasav): Sefer ha'Terumos (53) says that if salt absorbed blood or an Isur and it was put in a pot, if there is 60 times as much in the pot as the salt it is permitted. Even though the salt is Asur like a Neveilah and it gives taste to the pot, and taste is not Batel even in 1000, it is not more stringent than if all of it were blood or the Isur absorbed in it. Also Tosfos (Chulin 108b) says so. Sefer ha'Terumos also said that this refers to salt or spices that absorbed actual Isur. If they absorbed Kosher meat and they are put in milk, or vice-versa, we need 60 times only the amount of meat or milk absorbed in them, since they did not absorb Isur. The Tur said so above (Siman 94). The Tur brings from R. Shimshon and Riva that since the salt dissolves with the blood (and disperses throughout the pot and brings the Isur with it, one must estimate as if all the blood were salt). Semag says that they brought a proof. Sefer ha'Terumos says that this is only according to R. Tam, who says that a piece that absorbed any Isur becomes like a Neveilah. R. Efrayim says so only for meat and milk. If so, it suffices to have 60 times the Isur absorbed. We hold like R. Efrayim.

Taz (11): If Asur oil fell into a food, why is it Batel in 60? It is for taste! Granted, lard that falls into milk is Batel, for it is not forbidden due to itself, only due to the mixture. Since there is 60 parts of milk, there is no mixture (to forbid). However, oil is forbidden due to itself. Why is it Batel in 60? This should be like an egg laid on Yom Tov that was used to whiten a food. It is not Batel in 60, because it is for taste (OC 513). Even though there it mentions taste and appearance, here surely taste alone forbids. The Rema says 'as long as one can taste it.' One may not taste it, for perhaps there is taste! Rather, normally we assume that there is no taste in 60 parts of Heter, but if we taste it, it is not Batel. We do not say so about an egg, since it also colors. Therefore we are not lenient to say that a Davar she'Yesh Lo Matirim is Batel in 60, since perhaps it has taste. Isur v'Heter (25:6) says that anything for taste, e.g. anything sharp, like spices and salt of Hekdesh, is not Batel. He seems to hold that only sharp things are called Nosen Ta'am, but not oil. Even though oil gives taste and sweetens the food, it is not felt as much as a sharp food. Therefore, it is Batel like all Isurim. This is why the Rema concluded 'such as salt and spices.'

Shach (28): Other Stam Isurim are not for taste. They are Batel in 60, for they do not give taste to more than 60 times their own volume, unless one tastes them. Then, obviously they are forbidden! Therefore, if one tastes the Isur it is not Batel even in more than 60. Therefore, salt and spices are not Batel even in 1000, since normally they are for the sake of taste. Something added for taste is not Batel because presumably, it gives taste even in 1000. This is clear from Sefer ha'Terumos brought in the Beis Yosef. If so, if we know that there is no taste, e.g. one grain of salt or spices fell into a big pot, it is permitted. Toras Chatas (85) and Tosfos (66a Sof DH Tavlin) explicitly say so.

Shach (29): Isur v'Heter (25) says that it is mid'Rabanan that they are not Batel. He says that if we are unsure whether it can be tasted, Ohr Zaru'a permits giving it to Nochri to taste even nowadays (that normally we do not rely on Nochrim).

Shach (30): Toras Chatas (85) says that if salt and spices fell into something with the same name but a different taste, it is not Batel. If they fell into something with the same taste, it is Batel in 60.

Shach (31): The Beis Yosef proves that spices forbidden due to themselves are not Batel even if the Isur is mid'Rabanan. The Rashba connotes similarly, and also Isur v'Heter and the Rema (114:6), who say so about Stam wine of Nochrim, which is mid'Rabanan. The Poskim say so in many places.

Gra (35): Semag and the Mordechai (889) say that Riva and R. Shimshon disagree. They learn from Chulin 99b. Brine forbids only due to absorbed fat, and even so we gauge (Bitul) based on the vinegar and salt inside. This requires investigation. Perhaps they hold that R. Yosi in that Mishnah (Terumos 10:8) argues, and forbids only based on the amount of fat, therefore, he forbids only 16 times the amount of brine. They rule like him because the Sugya in Chulin 108 is like him. The Gemara learned from the Mishnah that not all Shi'urim ar the same, for R. Yosi would agree if the salt and water were forbidden due to themselves.