פירוש על עבודה זרה 146:10

Rav and Shmuel’s reading of the mishnah adheres closely to the simple meaning. Any time two of the same substance become mixed together, one permitted and one forbidden, for instance terumah wine with regular wine, the mixture will be prohibited no matter how small a quantity of prohibited substance. But if the substances are different, for instance lard in a pancake mixture, the mixture is prohibited only if the prohibited substance imparts a flavor. The last line of the mishnah indicates that this is true no matter what the prohibition.