I have a bottle of Lakewood Organic Concord Grape Juice. It is certified by Kof-K as pareve and kosher for passover. However, I cannot find anything on the bottle that would indicate it to be mevushal, but it does say that it is pasteurized. Can I assume that the pasteurization takes the place of the boiling for the sake of being mevushal? If the bottle is transparent and it is not mevushal, wouldn't that basically assure that it is not kosher?
Wine may be pasteurized at different temperatures. Igros Moshe maintains that above 175 degrees Fahrenheit the juice is considered mevushal. The Tzelemer Rav maintains that it is not mevushal.
The following is the position the OU states Kedem follows (source):
The Grape Juice bottles that state on their labels Mevushal are accepted by all as Mevushal.
The Grape Juice bottles that state on their labels Not Mevushal are accepted by all as Not Mevushal.
The Grape Juice bottles that do not state on their labels Mevushal or Not Mevushal:
A) according to the Tzelihmer Rav Zt”l are not Mevushal.
B) according to Rav Moshe Feinstein Zt”l and the OU are Mevushal.
see also here
The Kof-k seems to follow the opinion of Rav Moshe Feinstein, here, but is not definitive.
Clear bottles of non-mevushal wine do not pose a halachic problem, but according to some interpretations of the Zohar non mevushal wine is prohibited even if a non-Jew sees the wine which is possible with clear bottles. This opinion is followed by some Chasidim, in particular.
This is a Machlokes, explained at length here. Basically the American custom is to be lenient in the matter like Rav Moshe Feinstein's Psak, that cooking at 175 degrees Fahrenheit/80 Celsius is sufficient. It is also the practice in Israel to be lenient.
There are plenty of more strict opinions on the matter, however.
Regarding the transparency, the Kabbalistic issue of the wine being seen by a non-Jew only forbids it for Kiddush, not for regular drinking. In addition, the Mekubal Rabbi Zev Greenglass held that while the wine is double sealed there is no issue.
I don't know what the Kof-K's policy is, but I have heard that Kedem specifically writes Mevushal only when it conforms to stricter opinions, and leaves it off when it doesn't, so as to not be stating affirmatively that it is Mevushal when it is not unanimous. Instead they just state that it is pasteurized, leaving an individual to ask their own Rav. It could be the Kof-K is doing the same here.