Tevul Yom, Chapter Three, Mishnah Four
1) Dough that had been mixed [with dough of terumah] or that had been leavened with yeast of terumah, is not disqualified by tevul yom.
a) Rabbi Yose and Rabbi Shimon declare it unfit.
2) Dough that had become susceptible [to uncleanness] by a liquid, and it was kneaded with produce juice, and later touched by a tevul yom:
a) Rabbi Elazar ben Judah of Barthotha says in the name of Rabbi Joshua: he disqualifies all of it.
b) Rabbi Akiva says in his name: he disqualifies only the part that he touched.
Section one: This section refers to hullin dough (non-sacred dough) that had been mixed up with some terumah dough or terumah yeast (starter dough). According to the first opinion, this dough is treated as if it were hullin dough and it is not disqualified if a tevul yom touches it. This is another leniency with regard to the rules governing a tevul yom.
Rabbi Yose and Rabbi Shimon disagree and say that since there is terumah mixed in with this dough, it is disqualified.
Section two: The dough was originally made susceptible to impurity by contact with a liquid. Then the dough was kneaded together with fruit juice, which does not cause produce susceptible to impurity. The question is: is all of the dough considered to be connected?
According to Rabbi Joshua, this dough is all considered connected and if the tevul yom touches one part, it is all disqualified.
Rabbi Akiva disagrees. He holds that just as fruit juice does not cause produce to be susceptible to impurity, it does not cause the dough to be connected. The only part that tevul yom disqualifies is the actual part that he touches.