I'm working on a piece for a Sefer my Kollel is putting out on the topic of making Kiddush on grape juice that's pasteurized or has sulfites added (primarily based on שו"ת מנחת שלמה חלק א סימן ד, תשובות והנהגות כרך ד סימן סט, אשרי האיש פרק ז' אות נ"ט, and ברכת שמואל (להרב שמואל דרזי) עמ' רמ"ג)
The Teshuvos Vehanhagos (see also Rav Elyashiv) says that although you can use use pasteurized grape juice since if you add yeast to it it will ferment , you cannot use grape juice with potassium metabisulfite since if you add yeast to it it will not ferment (see there for his Raya that in order to be allowed to use grape juice it has to be on its way to fermenting).
One thing I've discovered (and the Birchas Shmuel touches on this as well) is that if you add wine yeast to even pasteurized grape juice with sulfites added it will have no problem fermenting. I've done it myself. Additionally there are many ways to get the sulfites (free SO2) out (either by letting them dissipate or making them bind with something else) which would then allow you to even use regular yeasts (although they can't get the alcohol content as high). However, I have not found a good source as to whether the fact that you are able to add something else to grape juice to make it ferment is enough to make it considered on its way to fermenting (as Rav Elyashiv and the Teshuvos Vehanhagos say is necessary) without adding anything. I haven't found anyone who disagrees with this explicitly although I have seen a few Poskim who clearly would hold its okay. Certainly the Minhag is to be lenient- after all most people in America would have no problem with someone making Kiddush on Kedem grape juice. Does anyone have a strong Raya as to whether the fact that you could add/do something to the grape juice to cause it to ferment is enough to make you allowed to make Kiddush on it without adding anything?
By the way, although I'm not done working on this piece I gave it as a Shiur yesterday, in part because I wanted to see what everyone attending the Shiur had to say. Anyway I only had about 20 minutes so I didn't get through anywhere near everything anyway. You will notice that I did mention that I had an open bounty on this question on judaism.stackexchange ;) I only remembered to say the story I found at @user15464's link after I ended the recording since it wasn't in my original Shiur plan so I restarted the recording afterwards (I also added a few more details I found after doing some more research). If you want to hear the story just don't get scared off by the way the recording goes silent for five seconds. You can listen to the Shiur here and if you have any comments please let me know as soon as possible so I can make changes before I publish in the coming weeks.
Update- The Sefer was published a while ago. If you'd like to see how I handled this you can download the Sefer here and read it on page 36. I go through all the Halacha and science there as well.