Louis Pasteur (1822–1895), one of the founders of microbiology, was a French chemist responsible for remarkable breakthroughs in the causes and preventions of numerous diseases. He was best known for inventing a process, called pasteurization, that increases shelf life and prevents milk and wine from causing disease. This process involves heating up the liquid for the purpose of destroying bacteria, protozoa, molds, and yeast lurking in the liquid. There is a difference between pasteurization and sterilization, however.

Sterilization is designed to kill all microorganisms. The purpose of pasteurization is to reduce the number of viable pathogens so that disease will be highly unlikely. Why not use sterilization? It all boils down to taste (pun, of course, intended). Sterilization severely affects the taste and quality of most foods.

How does pasteurization affect the kashrus of wine? There are two prohibitions on wine: The first prohibition involves biblically forbidden wine. The Torah forbids the use of wine that was poured as a libation in the religious worship of foreign deities. The prohibition is quite strict in that any benefit whatsoever from this wine is proscribed. If we recall from our high school world literature class, Pontonous, the king’s squire in Homer’s Odyssey, “mixed the honey-hearted wine, and served it to all. And they poured forth as a libation before the blessed gods that keep the heavens wide…” This is a classical example of what the Torah was discussing. The second prohibition involves rabbinically forbidden wine. The rabbis forbade the consumption of wine that was poured or touched by a gentile. (The majority of poskim hold that the reason for the prohibition was to prevent intermarriage; see for example Tosfos Avodah Zarah 29b “VeYayin.”)

It is important to note that the rabbinic prohibition of stam yeinam is indeed a serious one. Rabbi Ada Danziger writes (Chochmas Adam Klal 75:1), “One who drinks rabbinically forbidden wine uproots his soul from the place that it was rooted in holiness and loses his share in the World to Come.” This is also clearly indicated in the Zohar. The Chida writes (Shiurei Berachah 123:2) that the punishment for violating the prohibition of stam yeinam is so severe the violator is reincarnated as a jackass. (Clearly, a number of Israeli politicians were not careful in the halachos of stam yeinam.) But here we have an interesting exception. The Gemara (Avodah Zarah, 30a) quotes the opinion of Rava that the prohibition upon gentile wine does not apply when the wine was previously cooked. This is the halachah as codified in the Yoreh Deah section of Shulchan Aruch (123:3).

The Rosh (in his halachos of tractate Avodah Zarah 2:13) explains that when a situation is uncommon, the rabbis never enacted their prohibitions. Since cooked wine is highly uncommon, the enactment was never made. Is the Rosh’s explanation the authoritative halachic explanation? Does this leniency still apply? Also, how do we define the term “cooked”?

The Shulchan Aruch states that it is considered mevushal—cooked mishehirtiach al gabei ha’eish—when it gets hot on the fire. The Vilna Gaon seems to understand these words as equivalent to yad soledes bo—when the hand becomes singed on account of the heat—as he references Rishonim that derived these parameters from the cooking of liquids on Shabbos. Rav Moshe Feinstein, zt’l (Igros Moshe Yoreh Deah, Vol. II No. 52 and Vol. III No. 1) rules in accordance with this view, as does Rav Ovadiah Yoseph (Yoreh Deah section of his Yabia Omer, Vol. 8 No. 15.) This is the view of the Rosh and the Geonim, too. The Shach (subparagraph 7), however, rules that the volume of wine must be detectably reduced on account of the cooking process. He rules in accordance with the view of the Rashba and the Ran in this regard. Rav Elyashiv (Kovetz Teshuvos, Vol. I No. 76) rules in accordance with the Shach, as does the Tzelemer Rav here in the United States.

So now we have defined the term “cooked.” It is a debate between poskim as to the exact temperature; according to the lenient opinion 175°F will suffice; according to the stricter opinion the temperature is at boiling point.

In modern times when cooked wine is commonplace, does the Talmud’s leniency still apply? Also, is pasteurization to be considered equivalent to the Talmud’s notion of “cooked wine?” Rav Elyashiv is of the opinion that the exception of cooked wine is no longer applicable because most wines are now being cooked. In Koveitz Teshuvos (1:75) he writes that the exception is no longer valid. According to Rav Elyashiv, housekeepers and waiters do not mix with wine. Obviously, Rav Moshe Feinstein disagreed.

(How this information will affect sales is anyone’s guess. Will wine sales go up, because so much wine will now be rendered invalid? Or will sales go down, because people don’t want the wine to become invalid?)

Rav Shlomo Zalman Auerbach, zt”l (Minchas Shlomo, Vol. 1, responsum 25) argues that pasteurization should not even be considered cooking at all, since the taste is not significantly changed. He cites the Rashba, Meiri, Sdei Chemed, and Kneses HaGedolah, who back up the idea that the leniency of cooking is based upon altered taste. The pasteurization is a flash pasteurization and the heated wine is recovered through sealed pipes. The taste, therefore, is not significantly altered. Notwithstanding the fact that there are many experts who can distinguish the tastes, Rav Shlomo Zalman writes that the majority of wine drinkers cannot. He, consequently, ruled that pasteurization is not considered “cooked,” but for different reasons than Rav Elyashiv.

Is it just gentile wine that is forbidden? What about a Jew who has turned his back on Judaism? This too is the subject of debate. The Chasam Sofer (in his novellae to Yoreh Deah chapter 124) rules that the wine of a Jew who has rejected his religion is not forbidden, since there is no prohibition of intermarriage in such a case. He writes that Rabbi Caro did not include a Jew who has rejected his religion in the prohibition in Shulchan Aruch, because in essence it is permitted. On the other hand, the Shach in the Nekudas haKeseph in Yoreh Deah chapter 124 writes clearly that they are included. The consensus of rabbinic thought is that one can be lenient only in the following three situations: Where darchei shalom is involved, in a case of serious monetary loss, or in a situation where Jewish outreach is involved. In a nutshell, the microbiological development of Louis Pasteur has given rise to a plethora of halachic thought and analysis.