Basically, food cubes with a large amount of nutrients and food energy compacted into a small cubes that don’t spoil, cause why wouldn’t a semi high tech society have an easyer way to eat food… they come in a generic nutrient blend and they are probably rather bland, but you could probably find them in packs at a grocery store…
also, Atomic Cube Proccessing Unit - ACPU for short, makes food cubes by consuming food “perhaphs normally enedible or low enjoyment from” .
food cubes should probably have twice the space consumption of vitamins