797. Finding Chometz on Pesach

111:17 If a person finds chometz in his house on chol hamoed, he must take it out and burn it. If there is at least an olive-sized amount (k'zayis), he first recites the bracha al bi'ur chometz. (Some authorities disagree – Mishnah Brurah 435:5.) One does not recite the bracha on less than a k'zayis (nor on something that is not actual chometz – ibid.). If one found chometz on yom tov, on Shabbos of chol hamoed, or on Shabbos that is erev Pesach - on any of which he would not be permitted to handle the chometz because it is muktzeh - he should cover it with a vessel until after yom tov or Shabbos, then burn it. If it was found on the last days of yom tov so that after yom tov, Pesach will be over, he burns it without a bracha, even if it is more than a k'zayis.

112:1 Some things contain a mixture of chometz, even though the chometz itself is not visible and there is only a taste from the chometz, such as if the chometz was removed from it. Such things may not be kept over Pesach. Something that did not have chometz in it at all but was cooked in a chometz pot, even if the pot was used within the previous 24 hours, or if something was pickled in a chometz pot, one may keep it over Pesach provided that it was cooked or pickled before Pesach. If the food was cooked or pickled on Pesach in a chometz pot, it must be removed.