One hundred pounds of grapes yields approximately fifty pounds of wine, so what happens to the other fifty pounds? The residual pieces of pulp and skin are called pomace and are often used for fertilizer or animal feed. Large wineries, though, sometimes use the pomace to produce other usable food products.

Pomace may be used to produce tartaric acid, Grappa (a type of wine), tannins, food colors, food flavors, pectin, grapeseed oil, grapeseed flour, etc. Natural food coloring is produced from the skins and tartaric acid is a white crystalline acid found on the walls of emptied wine barrels and among the grape remnants. Grapeseed oil and flour come from the seeds after they are thoroughly cleaned and dried.
The oil and flour are extracted by using hexane (a petroleum derived solvent that works similarly to alcohol as a degreaser and is used regularly to extract oil from cotton seeds and similar seeds). The remainder is derived
from the pomace or the marc of the grapes, which includes the seeds, skins and the stems.

Most of these byproducts are not produced at kosher wineries, which raises the question of whether we can use them for kosher food production. In the Pesach 5768 issue of Kosher Spirit, Rabbi Ahron Haskel discussed the production of kosher l’mehadrin tartaric acid, made exclusively from kosher wine. While it is exemplary to use only kosher l’mehadrin tartaric acid, it is certainly ot yet the standard in the kosher industry.

The Gemara says1: “The grape seeds and grape peels of idol worshippers, if they are moist, they are forbidden (to eat and even for other benefits, as Reb Yochanan explains), if they are dried out, it is permitted (even to eat). Reb Yehudah said in the name of Shmuel that for the twelve months after pressing they are considered moist. Afterwards, they are considered dry.”

The Gemara continues: Rav Zevid said, “The sediment of Aramean wine called (דורדיא) durdaya is permitted after twelve months have elapsed.” Tosafos quotes Rabbeinu Efraim, who says that if the sediments have been dried in an oven, it is permissible even before twelve months have elapsed. He therefore permitted using bread made with this sediment (note: cream of tartar acts like baking soda as a leavening agent and stabilizer).

Rabbeinu Tam vehemently disagreed. He explained that “durdaya is shmarim (sediments of the wine) that have been soaked and reused. In those days, it was common to make an inferior wine (similar to Grappa, though today Grappa is concentrated) out of the sediments of the wine. Rabbeinu Tam opines that the twelve months of drying can only begin after the sediments have been cleared of any wine taste. The Rashba says that the same would apply to the sediments left on the barrels; they would only be permitted after twelve months. [Note: The Rashba says this to explain why people have permitted using it, though there are some who say that it is best to be more stringent.]

The Shulchan Oruch paskenslike Rabbeinu Tam, ruling that after the sediments have been reused (soaked and used to make an inferior type of wine) “tamdun” and then twelve months have elapsed, the sediments could be considered kosher. Shulchan Oruch also saysthat there are those who permit scraping off the remnants from the wine caskets and waiting a year to use them. Clearly, this is the accepted opinion as tartaric acid was traditionally made from the hard, stone-like material that hardened on the barrels and was called “vayn shtayn” in Yiddish (wine stone). Many of the poskim have discussed the halachic status of tartaric acid and why it was permitted.

Today, tartaric acid is dried mechanically to about 8% moisture (note: dried rice has about 11% moisture). Though there are some opinions that require twelve months of natural drying (Perisha and others), most hechsherim permit mechanical drying.

In addition, there are some companies that make tartaric acid by concentrating grape juice, separating the tartaric acid with a centrifuge, and then drying it thoroughly. In this case, many hechsherim permit this method. HaRav M.M. Weissmandl שליט”א, in his teshuvos to the OK, does not permit this approach.

As for grapeseed oil, there is a teshuva from the Chasam Soferdiscussing the process of removing the oil from the grape seeds. The Chasam Sofer concluded that grapeseed oil would be permitted even if the seeds were not dried for twelve months, because the oil does not have any grape taste and is considered “nishtanah” (changed to a new food).

This heter from the Chasasm Sofer cannot be used for grapeseed extract or grapeseed flour since the pomace or skins can also be used in the production. In addition, there are often remnants of a fruity taste in the final product. Originally, a leading kosher supervision permitted grapeseed extract, because they considered the grapeseed to be a piece of wood. About ten years ago, Rabbi Shlomo Miller wrote a teshuva prohibiting grapeseed extract until the twelve months of drying had passed, so the agency no longer permits grapeseed extract from seeds that have not been dried.

As you can see, kosher wine production is a lot more than meets the eye. It encompasses many facets of the kosher food industry, from actual bottled wine and grape juice, to the various byproducts discussed here.

Please feel free to send your comments or questions to

1. Avoda Zara, Daf 34a.
2. Yoreh Deah, Siman 123, S’if 14.
3. Yoreh Deah, Siman 123, S’if 16.
4. Yoreh Deah, Siman 117.



I would like to thank my esteemed readers for their comments on previous installments.

In my previous article, I mentioned that Rav Moshe Feinstein paskened that wine that was cooked to 165˚F or 175˚F is considered mevushal and the Tzelemer Rov held that it must be cooked to 190˚F to be considered mevushal. I also insinuated that this was possibly based on the various interpretations of the Rambam’s opinion that the wine must evaporate and lose some of its volume to be considered mevushal. Water actually begins to evaporate at room temperature. When you leave a wet plate out on the counter, it will dry after some time has passed, but the evaporation is clearly minimal. When it comes to discussing evaporation points, one is generally referring to the point when liquid changes to steam, which happens with water at sea level at a temperature of 212˚F (100˚C).

What about wine? At what temperature does it change from liquid to steam? The answer is a bit complicated since the wine is made up of water and alcohol (which comes from the fermented sugars in the wine). First, it is necessary to go over the process of distilling. When there are two liquids mixed together and they need to be separated, one uses a process called distilling. Since the boiling point of alcohol is lower than the boiling point of water, it is easy to separate the two. To accomplish this, the wine is cooked until the acohol’s boiling point and all of the alcohol is allowed to turn into steam. Usually, when one boils something, the steam rises and gets mixed into the atmosphere. In this case though, the cooking pot is covered and the steam is forced into a thin tube. This tube empties into another pot where it is cooled below the alcohol’s boiling point, which allows the steam to turn back into liquid. The liquid contains only the alcohol from the wine, and if distillation is done properly, the resulting liquid is clear wine alcohol.

At what temperature does distillation happen? The optimal temperature to distill alcohol is from 172-180˚F, which results in the purest alcohol, known as the “heart”. If distillation is done between 165-172˚F, it results in slightly impure alcohol, known as the “head”. When alcohol is distilled between 180-185˚F, the resulting alcohol is also slightly impure, known as the “tail”. Accordingly, this data seems to strongly support Rav Moshe’s opinion that loss of volume begins at 165˚F.