We'd probably say 'votive offering' rather than 'votive food'.

Like Karen, I'm a little unsure what you mean. To "donate" food usually means that you're giving food to poor people. Religious groups and charity groups often allow people to give food donations, and the food is then given to poor people. If you're talking about food that is given as an offering to a dead person (or a god, etc.) as part of a religious ritual, then we would just call it an "offering." Offerings aren't always food, but as far as I know, we don't really have a word that means "an offering that is food."

To be honest, I don't think we have such a concept. You might simply need to describe it. Votive is more about an offering to God or a god, not to humans. Giving alms might be the closest you get to that concept - something given to poor people as a religious duty.