Rif Pesachim 13b {Pesachim 43a continues; 45a-b}

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13b

{Pesachim 43a continues}
but there still is a prohibition.
And also, when the Sages say that he incurs no lashes, these words are so when there is not an olive's measure in the amount of time it would take to eat a peras {=4 egg measures} {Rashi: That if he ate a peras from the mixture, there would be an olive's measure of chametz}, such as Babylonian kutach. But if there were an olive's measure in the time to eat a peras, even according to the Sages he would incur lashes.

{Pesachim 45a}
Mishna:
Dough in the crevices of the kneading trough -- if there is an olive's measure in one location, he is obligated to remove it. And if not, it is nullified due to its smallness.
And so to in terms of the laws of ritual impurity. If he is particular about it {=the dough}, it separates, but if he wishes it to stay, it is like the kneading trough.

Dull dough -- if there is there {another dough} the same as it {made at the same time} which exhibits signs of rising, it is forbidden.

Gemara:
"And if not, it is nullified due to its smallness":
Rav Yehuda cited Shmuel: They learnt this only where it was {placed there} in order to strengthen {the trough}, but where it was not there to strengthen, he is obligated to remove.

We may deduce that an olive's measure, even where it was there to strenghten, he must remove.

{Pesachim 45b}
The Sages learnt {in a brayta}: The troughs of the tanners into which flour was placed, within three days he is required to remove it. After three days he is not required to remove it. Rabbi Natan said: Regarding what were these words said? When he did not place within it {=the trough} hides {to be tanned}, but if he placed in it hides, even within three days.

Rava said: The halacha is like Rabbi Natan, and even if for one day and even one hour.

The Sages learnt {in a brayta}: If bread became moldy and became unfit for human consumption but a dog is able to eat it, it can become impure with the ritual impurity of foods as long as it is the size of an egg, and may be burned together with impure things on Pesach.
This implies that if it became unfit to be consumed by a dog,