T.S.
My son was doing this for a while...I think he picked it up at his child care center. I sat down with him and explained what "hate" means. We then when through and explained the difference between dislike and hate. I then asked if he really hated eggplant or did he perhaps dislike it? We when through a few other examples and I think he understands that hate is a very strong emotion that should be reserved for things that truly deserved it. Every now and then he forgets, but he usually corrects himself now.
Good luck!