@M.A.R. Well, the carcinogens reason would be offtopic for our site, and the OP said explicitly that they are not interested in a difference in taste. The question seems to have been asked in search for knowledge for its own sake. I would find it answerable even without a purpose being named, if it is specified as "difference in X", where X is clearly measurable. And yes, naming the desired food would be a large improvement.

@rumtscho then I suppose my latter message applies. Been a while since I've had any meaningful activity on main, but I'm pretty sure there's only two ways a question like this can get any answers: 1) If the OP is superspecific, as in, "What happens to [ingredient] when it changes color/tastes sweet/becomes crunchy when fried/boiled/steamed?", or

2) if a very charismatic and inquisitive OP convinces in not few and not many words answerers to give common examples of reactions that happen so we call something cooked. Like if someone went to Seasoned Advice and asked, I dunno, how many ways there are to prepare eggs, and chose the exact wording to soften the curators until the question became too popular to close/delete.