A brand was a recognized product sold under a specific name.
According to a commercial, Tribbles was a leading cereal brand. The commercial boasted that it had more Human DNA than any other leading brands. (ST: "The Trouble with Edward", credit cookie)
In 2268, Doctor Leonard McCoy asserted that his theragen derivative, when mixed with alcohol, prevented nerve signals from reaching one's brain. Montgomery Scott then quipped, "Oh, well, any decent brand of Scotch will do that." (TOS: "The Tholian Web")