Laws of Mixtures

There are two fundamental rules regarding forbidden foods that became mixed with permitted foods. The first rule is bitul be-shishim (nullification in sixty): if the forbidden food became mixed into a quantity whose volume is sixty times greater than it, its taste is not perceptible, and the mixture is permitted to be eaten. For this is how the Sages estimated: if the permitted food contains sixty times the forbidden food, it is known that the taste of the forbidden food is nullified, because even foods with a very strong taste, such as onion, do not impart taste into more than sixty times their volume (Ḥullin 97b; Ran and Ra’avya).

The second rule is bitul be-rov (nullification in a majority): if the forbidden food does not impart taste to the mixture, we follow the majority. For example, a piece of tereifa meat that became mixed with two pieces of kosher meat of the same kind is nullified in the majority, as it is stated: “Follow the majority” (Shemot 23:2) (SA YD 109:1; below, section 8).

For the forbidden food to impart taste to the permitted food, two conditions must be met. First, the mixture must be min be-she’eino mino (one kind in a different kind); that is, the taste of the forbidden food differs from the taste of the permitted food, and therefore it can be perceptible in it. Second, the mixture must be laḥ be-laḥ (liquid in liquid, i.e., blended), for then the taste of the forbidden food merges into the mixture. For example, when milk mixes into a meat soup, its taste spreads throughout the soup. Likewise, when a piece of tereifa meat is cooked with vegetables, the taste of the tereifa mixes into the vegetables.

However, if one of the two conditions is not met, then even though the forbidden and the permitted are mixed, the taste of the forbidden food does not spread into the permitted food. For example, if a forbidden piece of meat became mixed with two permitted pieces of meat that have a different taste, even though this is a mixture of min be-she’eino mino, since the mixture is yavesh be-yavesh (dry in dry, i.e., discrete pieces), the taste of the forbidden food does not pass into the permitted foods, and therefore by Torah law the forbidden food is nullified in the majority. Likewise, when gravy of tereifa meat became mixed with gravy of kosher meat, even though the mixture is laḥ be-laḥ and the forbidden merges with the permitted, since the taste of the forbidden is like the taste of the permitted, it does not impart taste to it, and therefore by Torah law the forbidden food is nullified in the majority.

However, the Sages made a protective fence for the Torah and enacted that even when only one of the two conditions that allow the transfer of taste is met – either the mixture is laḥ be-laḥ, or it is min be-she’eino mino – the forbidden food is not nullified in a majority; rather, sixty times its volume is required to nullify it (Rashba and Rosh). The Sages had another important aim in their enactment: to make the measures uniform, so that there would be a single rule of nullification in sixty for all mixtures that resemble a mixture in which the forbidden food can impart taste (Ran). Therefore, even when the basis of the prohibition is rabbinic, we do not say that there is no need to make a fence for it; rather, sixty times its volume is required to nullify it, because the Sages made their measures uniform (BY and Rema 109:1).^¹