Green’s Dictionary of Slang

to sample or enjoy one’s food and drink.

1815		(con. 18C) W. Scott Guy Mannering (1823) 161: A tall, stout, country-looking man [...] busy discussing huge slices of cold boiled beef.
1836		Marryat Mr Midshipman Easy I 3: They allowed him to discuss the question, while they discussed his port wine.
1861		W. Thornbury J.M.W. Turner II 264: Turner was always to be seen between ten and eleven at the Athenæum, discussing his half-pint of sherry. As his health failed, he became very talkative after his wine, and rather dogmatic.
1885		Lord Malmesbury Memoirs of Ex-Minister 562: The time was passed in discussing a substantial luncheon .
1900		Bulletin (Sydney) 20 Oct. 14/4: The Dick Turpin legends set forth that mare ‘Black Bess’ used to discuss an occasional beef-steak. Present writer has seen several horses eat meat.