Isaiah 65:8 "Thus saith the LORD, As the new wine is found in the cluster, and one saith, Destroy it not; for a blessing is in it: so will I do for my servants' sakes, that I may not destroy them all."
Then in the below verse we see that new wine is called the "fruit of the vine". At the Lord's Supper they were drinking new wine(grape juice), not fermented wine which is old and spoiled.
Matthew 26:29 "But I say unto you, I will not drink henceforth of this fruit of the vine, until that day when I drink it new with you in my Father's kingdom."
New wine can be made by squeezing a bunch of grapes into a cup according to the below verse.
Genesis 49:11 "And Pharaoh's cup was in my hand: and I took the grapes, and pressed them into Pharaoh's cup, and I gave the cup into Pharaoh's hand."
Kings and Pharaoh's could have new wine, grape juice, anytime they desired as they would call on their cup bearer to press the grapes for juice. It was for the privileged.