For the violation of the “I will not eat” oath, Rabbi Akiva obligates one for even a minute amount. Why is this?
Is it because he follows the opinion of Rabbi Shimon, who obligates one for any prohibited food for even a minute amount? If so, Rabbi Akiva should disagree in general and say to the Sages, “I obligate for any food violation, regardless of amount!” No, this idea is incorrect. Rabbi Akiva could simply be answering the Sages according to their words: “I say, one is liable for any amount of forbidden food. You, the Sages, who don't hold so, should at least agree with me in the instance of an oath, where he violates his oath, not just the food prohibition.”
It could also be that in general Rabbi Akiva does not follow the opinion of Rabbi Shimon and obligates for eating forbidden foods only if a specific amount is consumed. Here, however, Rabbi Akiva says that the one who takes an oath “I will not eat” means it in the common sense of eating, and small amounts are included.
The second explanation is the preferred one.
Art: Georges de La Tour - Peasant Couple Eating