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Kosher Wine Pasteurization and Mevushal




If left on its own, grape juice, as well as milk, fruit juice, or other organic liquids, will over the course of time simply and naturally transform itself to vinegar. It is only human intervention, creativity and incredible dedication that manage an anaerobic microbiological transformation to create fine wine, including kosher wine. If wine is exposed to air (oxygen) the pathogens (bacteria) in the air will still achieve their natural ambition making it sour (vinegar).

I have seen references that the process of heating wine for preservation purposes has been known in China since 1117, and was documented in Japan in 1568. Certainly, in 1863 the English were refusing to take delivery of French wines due to spoiling (souring). Emperor Napoleon III commissioned Louis Pasteur to study the problem. In 1865 he published a paper called “Studies on Wine” which explained the “wine sickness” and the way to fight it with a process we now call pasteurization; a process on which he took out a patent. Louis Pasteur also discovered that living yeast cells were the secret to fermentation. He published a series of papers on fermentation starting in 1857.

It should be noted that today the overwhelming majority of kosher wine, non kosher wine and fruit juice is pasteurized for shelf stabilization purposes. Virtually all non vintage, table, or box wines, which are typically not required to have an expiration date, are so treated to be stable without refrigeration prior to opening.

To properly understand pasteurization today it needs to be noted it is comprised of heating and cooling the liquid in a continuous closed system and there can be many variations employed. It may refer to a range of process variables as shown by the table of typical pasteurization temperatures and times that follow:

135 55 few minutes Louis Pasteur - 1862 *
145 63 30 minutes Vat Pasteurization (Milk) **
162 72 20 seconds Flash Pasteurization (HTST) ***
175 80 Moshe Feinstein - Yad Soledes
194 90 0.5 seconds Tzelemer Rav (Kedem)
212 100 .01 seconds HHST
275 135 1.0-2.0 seconds UHT – Shelf Stable Milk ****

* Original patent.
** Also common for beer and wine.
*** HTST - High Temperature Short Time
**** UHT - Ultra High Temperature, very popular in many countries
but only slowly gaining acceptance in the US.

Flash Pasteurization

An early adopter of Flash Pasteurization HTST was Tropicana Products (often credited with developing the process), which has used the method since the 1950s. The juice company Odwalla switched from non-pasteurized to flash-pasteurized juices in 1996 after tainted unpasteurized apple juice containing E. coli bacteria sickened many children and killed one.


There are two categories of kosher wine. Mevushal wine undergoes an additional process, translated as “boiling”. Where in the past wines were literally boiled these days they are often flash pasteurized. This is important because halacha (jewish law) makes a distinction on the ability of a wine to retain its kosher status if for example it has been opened and poured by a non Jew such as a waiter.

Wine has been used for many purposes, including as a libation offering (or pouring) in a religious service, often for idolatry or pagan worship. The Torah’s prohibition against idolatry is so strong that it was important to include in the prohibition the liquid employed in this non-kosher use, and during Talmudic times a clear separation was established. Wine denoted for pagan worship was called yayin nesech—literally, libation wine. To distinguish it from stam yayin (which means regular wine), our sages decreed that only cooked, or “mevushal” wine was to be used. This process occurred in an open vessel which boiled off alcohol, deliberately degraded the quality of the wine by imparting a boiled flavor and character.

The Babylonian Talmud (Avoda Zara 29b) notes that cooked wine was of inferior quality and thus never used for pagan worship. This form of separation was continued in our traditions, in part as a remembrance of the importance of the misuse mentioned above, and in part because the sages determined it was consistent with the discouragement of casual socialization and the tragedy of intermarriage between Jews and the gentile population which led to the disaffection of large numbers of Jews from Judaism. Although mevushal wine is still favored by many, to ensure this separation, non-Mevushal wine is considered to have a higher level of kiddusha (holiness) by some, and is therefore preferable for sacramental use.

Minchag HaOlom, or the custom today, is to follow the approach of HaGaon R. Moshe Feinstein who ruled that flash pasteurization, which occurs in closed system, was adequate to satisfy the requirement of mevushal. However, not all Poskim (halachic authorities) agree that flash pasteurization renders the wine mevushal. HaGaon R. Shlomo Zalman Auerback z’l’ ruled that because the average person will not detect divergence it cannot be considered cooked. HaGoan R. Yosef Shalom Eliashiv z’l’ ruled the heter (lenient exception) is based on reasoning that mevushal was not common practice. As it is very common today it would not apply. Further, as another reason is to discourage casual socialization the prohibition of stam yain (non mevushal wine) it should extend to even mevushal wines as well.

Many wineries, especially in Israel, will not mevushal their better wines as it is expected that branding it as such would reduce the perceived value. There is also a principal in the traditions of wine making that one should not do anything to a wine that is not needed. For example, fining is a common process that employs an additive to agglomerate dead suspended yeast, so it can be more easily filtered. However, some claim that even fining and filtering are detrimental; instead, they rack or siphon off liquid after sediment is allowed to settle. There are premium unfiltered wines that claim to be superior; they are more expensive and often excellent – but racking is by no means a universally accepted process among premium winemakers. Similarly, not all premium winemakers shun the flash pasteurization process. In fact, flash pasteurization has also been increasingly adopted by fine non kosher French wine producers like Chateau Beaucastle or Chateau Latour as a valuable production tool and technique for to stabilize the grape must (the juice prior to or during fermentation).

Reliable research on Pasteurization of Young Red wine was conducted at UC Davis using spectrophotometry and gas chromatography to measure aging variables and sensory evaluation using statistically valid blind tasting methods by very skilled panel of judges. The conclusion was it cannot be reliably detected and “the impact of this treatment for young red wine is not significant.” It even suggests that rates of heating in a closed anaerobic system are not a significant process variable.

Yet, claims that mevushal wines do not age well and don’t last as long persist. Welcome to the world of wine. In my view, these claims may be true of some but certainly not of the better mevushal wines. When true, it is likely to have far less to do with mevushal than other process variables, like when the mevushal process is applied.

I have tasted many newer wines that have been finely crafted as mevushal by extraordinary winemakers and can tell you that some are just spectacular with the promise of very long cellar aging potential yet they are also more approachable when young as well.

So, in summary, while it may sometimes be possible to tell if a wine is mevushal, particularly if the process is aggressive; in better wines, where flash pasteurization is employed, there is no evidence to suggest the mevushal process can be perceived. Pretense and claims will continue by those who cannot otherwise be challenged that “they can tell” it is far more likely to be affectation than reality.