Dehydrated food was any foodstuff from which water had been removed (or dried) in order to allow for long-term storage. Paprika was an example of a dried seasoning.
Grapes could be dried out to make raisins by raisin farmers. (LD: "Grounded", "Crisis Point 2: Paradoxus")
Among the camp rations kept by Carmen Davila, a member of the first group of colonists arrived at Melona IV in 2368, was the dried chicken curry that she had been saving. (TNG: "Silicon Avatar")
Starfleet ration pack 5 consisted of stewed tomatoes and dehydrated eggs. (VOY: "Phage")
Astronauts consumed dehydrated food. In 2032, Lieutenant John Kelly attributed his sighting of a spacecraft to the dehydrated food going to his head. (VOY: "One Small Step")