Was the wine in The Last Supper fermented? I was reading "Does wine really mean wine in the Bible?" and I thought, The Last Supper was during the Passover, where the jewish was forbidden to use ferment in recipes: 


  Exodus 12:15 KJV
  Seven days shall ye eat unleavened bread; even the
  first day ye shall put away leaven out of your houses: for whosoever
  eateth leavened bread from the first day until the seventh day, that
  soul shall be cut off from Israel.


This implies that the wine used in the The Last Supper was just grape juice, right?
Prior to the advent of pasteurization, fermentation was something which happened in all grape juice whether a fermenting agent was consciously introduced or not (and it happened with relative immediacy). The last supper, then, would have had wine and not plain grape juice.

It is also noteworthy to point out that wine, unless something bizarre has occurred, is not leavened bread.