Mixes in is a phrasal verb which means to blend or combine with something else. Antonyms of mixes in can differ based on the context. For instance, if the context refers to food, the antonym is to separate or isolate. If it's about people, the antonym would be to exclude, alienate, or segregate. In a scientific experiment, the antonym would be to avoid or omit. In the context of music, the antonym is to differentiate or distinguish, extracting the distinctness of each instrument. In conclusion, antonyms of mixes in vary according to circumstances, but generally imply the act of separating, excluding, avoiding, differentiating, or distinguishing.