to take away the natural qualities of (something or somebody)
to modify (e.g. a protein) by heat, acid, etc so that some of the original structure of the molecule is lost and its properties are changed
to make (alcohol) unfit for drinking, (e.g. by adding an obnoxious substance)
denaturant /deeʹnaychərənt, deeʹna-/ noun
denaturation /ˌdeenaychəʹraysh(ə)n, ˌdeenachəʹraysh(ə)n/ noun