A person took an oath that he will not drink this milk. Thereafter that milk turned into yoghurt and he consumed it. His oath will not break.
A person had a kid goat and took an oath that he will not consume the meat of that kid. After that kid grew into a fully grown adult goat, he consumed its meat. His oath will break.
A person took an oath that he will not consume any meat. Thereafter, he consumed some fish, liver or the tripe of an animal. His oath will not break.
A person took an oath that he will not eat this wheat. Thereafter, this wheat was ground and made into bread or a dish made of crushed wheat. If he consumes any of these, his oath will not break. But if he boils or roasts the wheat and consumes it, his oath will break. However, if at the time of taking the oath, the person intended that he will not consume anything made from it, then his oath will break with anything that is made from it.