A well-established Halacha forbids partaking of wine or grape juice that had been handled by a gentile or Shabbat violator, unless the wine is "Mevushal," meaning, it had been cooked. The question arises, does the process of pasteurization, which entails heating wine to a temperature exceeding 170 degrees Fahrenheit, suffice to render wine Mevushal?
Hacham Bension Abba Shaul (Jerusalem, 1923-1998), in his work Or Le'sion (vol. 2, p. 187), ruled that pasteurization does not qualify as "cooking" with respect to the Halacha of wine handled by a gentile. He notes that the Shach (commentary to the Shulhan Aruch by Rabbi Shabtai Ha'kohen, 1621-1662), in his commentary to Yoreh De'a (123), rules that wine is considered Mevushal only if its quantity diminished somewhat as a result of boiling. Pasteurization is performed in a closed container such that the full quantity of the wine is retained. Hence, according to Hacham Bension, pasteurization does not meet the qualifications of Mevushal, and one may therefore not partake of pasteurized wine that had been handled by a gentile, unless the wine had also been boiled in an open utensil.
Hacham Ovadia Yosef, however, in his work Yabia Omer (vol. 9, p. 256), disagrees. He cites the work Ma'aseh Ha'ge'onim (p. 77) as recording the view of several Geonim that the wine's quantity does not have to be diminished for the boiling to render the wine Mevushal. Hacham Ovadia further notes that the Shulhan Aruch (Yoreh De'a 123:3) defines "Yayin Mevushal" as wine that has been brought to a boil over a fire, making no mention whatsoever of its diminished quantity. Accordingly, Hacham Ovadia contends that pasteurization does, in fact, qualify as "cooking" with respect to the status of wine, and it is therefore permissible to drink pasteurized wine or grape juice that had been handled by a gentile or Shabbat violator. This is also the position taken by Rabbi Moshe Feinstein (Russia-America, 1895-1986), in his work Iggerot Moshe (3:31). In fact, he extended this ruling even further, claiming that wine is deemed Mevushal even it only eached the temperature of "Yad Soledet Bo" (the point at which one's hand would immediately recoil on contact), even if did not reach a boil.
Summary: Halacha forbids partaking of wine or grape juice that had been handled by a non-Jew or Shabbat violator, unless it had been brought to a boil, such as through the process of pasteurization.
