John 2:3ff And when they wanted wine, the mother of Jesus saith unto him, They have no wine.
This is the one that really gets the pot boiling, since if Jesus produced wine with alcoholic content, this is clear evidence that there is some leeway for consumption of alcohol. Bacchiocchi [Bac.W, 138ff] notes the possibility that oinos refers to unfermented grape juice, but as this is only a possibility, it is not conclusive. One defining argument is that the governor of the feast called the oinos "good wine", and Bacchiocchi's comment that this title was commonly given to wines that had been filtered so as to temper its effects [Bac.W, 129]. The filtering removed much (but apparently not all) of the intoxicating effects, enabling more to be consumed. Bacchiocchi jumps to the conclusion that this equates with total prohibition, but as he does not show that the filtering process removed all alcoholic content, the argument cannot be taken so far, so easily.
Of perhaps more persuasive bearing is the theological argument that the miracle of Cana, representing as it did an divine act of creation, indicates that there was no fermentation, because unfermented wine is "the only wine God produces" in nature. But it is questionable whether the analogy can be pressed so far. The water was originally drawn by men; how does this fit in? Furthermore, to make the point that fermentation is a "process of decay", while scientifically and technically true, does not hold much strength since decay of some kind begins in nature anyway, even if it is not specifically fermentation. I am reminded here of skeptics who say that Jesus could not have been the Passover lamb because he was whipped first and was therefore not without blemish. Typological matching does not require full precision in any scenario.