Brine was water with a high salt content.
Brine was an ingredient in Bajoran hasperat. Macias asked Ro Laren to prepare brine for a very strong hasperat in 2370. (TNG: "Preemptive Strike")
In 2372, Neelix served brine-soaked niccel strips for lunch aboard the USS Voyager. (VOY: "Persistence of Vision")
The Moneans had a saying, "brine in the veins", referring to their special connection to the Waters. (VOY: "Thirty Days")