YA/children's story,post-apocalyptic dome city

I remember a story from about 1994, about a boy and girl trying to escape from a domed (or otherwise protected) city into the post-apocalyptic wilderness beyond. They meet an old man on the outside (who they may or may not have previously met in the city, I can't recall), and it seems to have been heavily inspired by the film version of Logan's Run, but with younger protagonists. My memory is very hazy on this, but I remember that the main characters are intrigued by the smell of oranges as they near the city exit (as they've never encountered fruit or vegetables), if that's of any limited help.

This time of darkness by H. M. Hoover has a plot similar to the one you describe, and the main characters do eat an orange for the first time in their lives after escaping.

Yes, you're right, that's the one. Thank you very much!