Jesus Christ commanded his disciples to eat bread and drink wine in remembrance of him. Like bread, wine is a byproduct of human intervention and effort. The vineyard was planted and tended to, and the fruit was harvested and crushed to extract the juice. The juice was allowed to ferment in the open air by the naturally-occurring yeast from the grape skin and then gathered into goat skins for preservation. (source) The wine used at passover and at the last supper would have to have been fermented wine since it would have been harvested in the fall six months prior. Unfermented grape juice could have been obtained straight from the grapes at harvest time, but didn’t exist as a product until 1869 when Dr. Thomas Bramwell Welch utilized pasteurization to create “unfermented sacramental wine” for his fellow Methodist church members. (source)
“Then he took a cup, gave thanks, and gave it to them, saying, Drink from it, all of you, for this is my blood of the covenant, which will be shed on behalf of many for the forgiveness of sins. I tell you, from now on I shall not drink this fruit of the vine until the day when I drink it with you new in the kingdom of my Father.”
Matthew 26:27-29
“And this shall ye always do to those who repent and are baptized in my name; and ye shall do it in remembrance of my blood, which I have shed for you, that ye may witness unto the Father that ye do always remember me. And if ye do always remember me ye shall have my Spirit to be with you.”
3 Nephi 18:11
“The manner of administering the wine—Behold, they took the cup, and said: O God, the Eternal Father, we ask thee, in the name of thy Son, Jesus Christ, to bless and sanctify this wine to the souls of all those who drink of it, that they may do it in remembrance of the blood of thy Son, which was shed for them; that they may witness unto thee, O God, the Eternal Father, that they do always remember him, that they may have his Spirit to be with them. Amen.”
Moroni 5
“Likewise, no one pours new wine into old wineskins. Otherwise, the wine will burst the skins, and both the wine and the skins are ruined. Rather, new wine is poured into fresh wineskins.”
Mark 2:22