Are you allowed to bring in outside food?

Yes, you may bring your own food, we just request no glass or straws.

I have seen people and groups with their own food. It does however mention in rules about glass bottles and straws. https://www.zooknoxville.org/visitor-info/zoo-rules/

I didn't see anything posted that said you couldn't. If you want to know for sure just check their website or call.