An Unfermented wine is created when a player with a cooking level of 35 or more uses grapes with a jug of water. After 12 seconds, this item will automatically turn to either a jug of wine or a jug of bad wine, giving 200 cooking experience for the former situation and none at all for the latter. The player will also stop making bad wine at level 68 cooking.
A player creating a jug of wine.
It can ferment in your bank, but if you keep making more and depositing it in the bank, it will not ferment until you stop making Unfermented wine for 12 seconds. It should be noted that unfermented wine would not ferment if you drop it. It must stay in your inventory or your bank for the duration without a break to ferment.
Using wines, it is possible to get up to almost 200 million experience in one XP drop. As making wine stalls the experience drop and the wines will not ferment while the player is logged out (for any period of time), allowing the player to make as many wines as they have in their bank as long as they don't stay logged in for 12 seconds without making more.