I've been painting glassware for quite some time and most of the paints that I have either looked at, or tried, have stated..... "You should not paint on areas that come into contact with food".
I know that if you go to a ceramic shop and paint on unfired bisque, most of the paints available there will be food safe. Unfortunately, I have never found one for "home" use in any kind of craft store, or even from online internet searches, that advised that it was okay to paint on food surfaces. Also, most of the paints that you buy in craft stores are effected by heat (from food/dishwashers/microwaves/ovens/etc.) that causes the paint to become soft, for a period of time. Most of the glassware that I paint I caution on the use and cleaning of the item.
Sorry, wish I could be of more help, let me know if you find something that works!