With regard to all of the various kiddushes discussed in these pages of the Gemara (Friday night, Saturday, Yom Tov, Havdalah), does it make any difference if Kiddush is made on grape juice instead of wine? Is the alcoholic content of wine an important factor in the mitzva? Does the answer vary by which kiddush is involved?
Richard
In O.C.272 #2 The Shulchan Aruch rules that one may squeeze grapes and use the juice for Kidush. This is true for Kidush and Havdalah on all occasions other than the Pesach Seder.
For the 4 cups of Pesach there is a definite preference to use wine. On Daf 108b Rabbi Yehuda said that the 4 cups must have the appearance and taste of wine. The Rashbam DH Tzarich she'Yiheye Bo Ta'am Yayin writes that it should not be new, i.e. unmatured. Later in DH Al Tere Yayin he writes that since we are warned not to get drunk (Mishna Daf 117b, Rashbam DH Ben Shelishi l'Revi'i Lo Yishte). Evidently the taste reffered to is alchoholic.
Rav Shimon Eider in his Book on Hilchos Pesach (XX:B:5, footnote 37) quotes Rav Moshe Feinstein who said that one would fulfill the obligation of drinking four cups with grape juice, but not the obligation of "Cherus."
b'Verachah
Ilan Segal