Wine has an importance throughout Poe's story. He uses the fictitious Amontillado to lure Fortunato to his death. It should be noted that both men refer to the cask as a "pipe." This means a barrel containing 126 gallons. The quantity is important because it explains Fortunato's strong motivation to sample it.
Both Montresor and Fortunato are connoisseurs--but they are not interested in buying so much wine for private consumption. The size of the cask, plus the supposition that there is a whole shipload of identical casks newly arrived in Venice, suggests that a big financial profit can be made if they hurry. Everyone is involved in carnival revelry. No other potential buyers, including Luchesi, have heard the news. But once word gets out, there will be competitive bidding for Amontillado sherry, and the potential profit will shrink. Of course, this is all hypothetical, because the cask of Amontillado does not really exist.
When Montresor encounters Fortunato drunk and wearing a jester's costume, he tells his friendly enemy and business rival:
"But I have received a pipe of what passes for Amontillado, and I have my doubts....and I was silly enough to pay the full Amontillado price without consulting you in the matter. You were not to be found, and I was fearful of losing a bargain....I am on my way to Luchesi. If any one has a critical turn, it is he."
Montresor is pretending to be anxious to verify the quality of the wine that very night. The obvious implication is that he bought one cask but will buy more if assured it is genuine. Otherwise there would be no hurry. Fortunato does not have to sample Montresor's cask. He could easily make some excuse and find the Spanish ship himself. There he could bargain with the captain and, since he is a rich man, buy up the entire cargo. But if he begs off accompanying Montresor to his palazzo, Montresor implies that he will immediately run to Luchesi. Then Fortunato and Luchesi will be competing for the cargo.
Thus, the cleverly fabricated story forces Fortunato, though drunk, suffering from a bad cold, and inadequately dressed, to agree to sample Montresor's nonexistent wine that very night. Montresor knows full well that Fortunato is planning to taste the wine and declare it to be ordinary sherry, thereby eliminating Montresor as a competitor for the nonexistent casks aboard the nonexistent Spanish ship. Fortunato is thinking that if he finds the wine to be genuine Amontillado, he will buy up the whole cargo and add another injury to the "thousand injuries" he has already inflicted. When Montresor discovers he has been deceived, Fortunato will laugh it off as "an excellent jest." (He is not wearing a jester's costume because he wants to be taken for a fool, but because he thinks of himself as a clever jester.) If the wine is not genuine, he has lost nothing but his time.
‘‘The Cask of Amontillado’’ was first published in the November 1846 issue of Godey's Lady's Book, a monthly magazine from Philadelphia that published poems and stories by some of the best American writers of the nineteenth century, including Nathaniel Hawthorne, Henry Wadsworth Longfellow, and Harriet Beecher Stowe.
Ladies in 1846 did not drink whiskey or brandy, but they did occasionally sip a glass of sherry. It seems significant that Poe's story about sherry should have first appeared in a ladies' magazine, even though it has such a horrible theme.