2,449. When the Ratios Don't Apply

Maachalos Assuros 15:34

If the meat of a properly slaughtered kosher animal gets mixed with the meat of a neveila that was salted, the kosher meat is rendered prohibited. This is because the essence of the neveila gets absorbed into the kosher meat. It’s not possible to discern their flavor or to calculate the ratio of the prohibited thing. If the flesh of an unsalted species of kosher fish gets mixed with the flesh of an unkosher species of salted fish, the kosher fish is rendered prohibited from the non-kosher brine. However, if the kosher fish was salted and the non-kosher fish was unsalted, then the salted fish is not rendered prohibited because, even though the unsalted fish absorbs the brine of the salted fish, it doesn’t absorb so much that it will expel its own brine. If a non-kosher fish is pickled with a kosher fish, the mixture is prohibited unless the permitted is 200 times the volume of the prohibited.

Maachalos Assuros 16:1

All of the ratios given by the Sages for prohibited things that get mixed with permitted things of the same kind only apply when the prohibited thing isn’t a leavening agent, a spice or something noteworthy that remains as it is without getting blended throughout the permitted thing. If the prohibited thing is one of these, then even the smallest volume of it renders an entire mixture prohibited.