Fall 2024

In medieval folklore, alchemists were supposedly able to transform lead into gold. Their craft was the stuff of fantasy. But in contemporary life, through the wonders of kosher food science, we are witness to a veritable world of transformation. An impressive example of chemical transformation that would make an alchemist envious is the production of silica gel.

The Chemical Transformation of Sand

Silica gel is a desiccant. It is a highly versatile industrial product, used to absorb moisture in toothpaste, paint and telephone wires, among a myriad of other uses. Granules of silica gel fill the little white packets marked “do not swallow” in your shoe boxes. Kosher food applications include silica gel in spices as an anti-caking agent or as an absorbent in an oil refinery.

Chemically, the basic raw material for silica gel is sodium silicate. More simply, we know it as sand. When sodium silicate is mixed with sulfuric acid, caustic soda and ammonium hydroxide, and undergoes a process of mixing, washing, drying and milling, the result is a super versatile and economically vital product–silica gel–with a myriad of food, pharmaceutical and technical applications, all stemming from good old-fashioned sand!

The Halachic Transformation of Non-Kosher Wine Sediment

Halacha goes even further in its transformative powers. A material that is 100% treif– unquestionably non-kosher–can morph naturally into a basic kosher food ingredient. A perfect example of this is the production of cream of tartar. Non-kosher wine sediment found on the sides of wine casks–known in the language of the Shulchan Aruch as veinshtein–can undergo an amazing transformation to produce potassium bitartrate, also known as cream of tartar.

How does it work? Tártaros Gonzalo Castelló, a world leading manufacturer of cream of tartar, details the production process. They source potassium bitartrate from argol. Argol is obtained from sedimentation which accumulates on the walls of casks used to ferment wine (note that the wine is not necessarily kosher). Over the course of many years, a several-millimeters-thick coat of hardened sediment forms, which is eventually scraped off to harvest the argol. The argol is reacted with potassium carbonate to produce cream of tartar, a STAR-K certified kosher item.

The Transformative Power of Nullification: Afra d’Ara

The halachic wisdom behind the intriguing process of transitioning from non-kosher to kosher is contained within a fundamental kashrus principle known as afra d’ara (literally, dust of the earth).[1] “Dust of the earth” signifies complete nullification and can be recreated into a kosher entity with no relationship to its former self.

We see that principle beautifully applied in the production of cream of tartar. When grape must sediment in a wine cask becomes dry and crystalline, it loses every vestige of its former identity and can thus be transformed–in the words of the Mechaber, the Beis Yosef –into afra d’ara.

This principle has advantaged the kosher cream of tartar market. The high demand for this valuable industrial product has diminished the world’s supply of argol. To satisfy that demand while circumventing the long wait for sediment buildup, dregs from pressed grape juice productions–the shmorim, which are bountiful–are converted into afra d’ara to create the potassium bitartrate. Not only are the dregs dried under the hot Spanish sun, but tractors also actually run over them, further crushing them and literally transforming them into afra d’ara. The pulverized dregs are then placed inside a high heat reactor, purified and filtered, to produce high quality kosher potassium bitartrate.

Since Chazal established this afra d’ara principle, it is worth pondering if the principle can be extended further.

The Power of Nullification in the Aging of Scotch

Can we proceed to apply the transformative power of afra d’ara to non-kosher ex-sherry casks used to age scotch? Let’s first review the aging process and the use of ex-sherry casks.

Traditionally, a winemaker will ferment grape musts in a wooden oak barrel called a cask. Different varieties of wine–such as sherry, port and madeira–can be aged in these casks. (Those who remember reading “The Cask of Amontillado” by Edgar Allan Poe in high school may not know that amontillado is a variety of sherry wine.) Coopers (barrel craftsmen) fashion the casks out of curved wooden staves. (This will be an important detail to keep in mind for later.)

When the wine has finished aging, the cask is emptied and is ready for use as an ex-sherry cask. There is a brisk high-end resale market for ex-sherry casks, as opposed to ex-bourbon casks.[2] The latter are sold to scotch producers in Scotland, where wood is scarce and where they can fetch a price of $100-$200 per cask. A single ex-sherry cask, by contrast, can sell for $1000 or more.

Over five hundred years ago, Chazal referred to whiskey, a neutral grain spirit, as yayin saruf–literally, “burnt” or “fiery wine.” In a similar vein, Native Americans, when introduced to whiskey, famously termed it “firewater” in recognition of its pungent taste. Appropriately, halacha considers whiskey to be a davar charif–a “sharp” beverage.

The color of freshly distilled scotch whiskey is as clear as vodka or gin. To age scotch, distillers avail themselves of both ex-bourbon and ex-sherry casks. After aging for a minimum of eight years–the low end of the aging spectrum of scotch–the scotch acquires taste and color. The longer the age, the deeper the amber. Whereas bourbon aged in new casks can be ready after six years, scotch aged in an ex-wine cask takes a lot longer to reach its goal.

Now we’re ready to examine how the aging of whiskey in non-kosher ex-sherry casks affects the kashrus of the aged scotch. We know that veinshtein loses its identity after twelve months. Does an ex-sherry cask that has lain dormant for twelve months (or longer) similarly lose its wine identity? The answer is, yes. The Shulchan Aruch notes that vessels which have lain dormant for at least twelve months are permitted for kosher use, as any moisture within them will surely have evaporated in the interim and any remnant of wine in the wood will have been neutralized.[3]

I turned to STAR-K Rabbinic Administrator Rav Moshe Heinemann shlit”a for his insights. The Rav was quick to quote a Shach who distinguishes between casks used to age whiskey from  those that have been nullified via the afra d’ara principle: “…kol sh’misyashnim nosein taam l’shevach” – that which is aged imparts beneficial taste.[4] Based on the Shach, the Rav agrees that product aged in a wine cask improves over time. But an ex-sherry cask nullified through afra d’ara is permitted for the production of kosher scotch.[5]

Due to recent developments in the production of scotch, however, we are no longer necessarily dealing with truly “nullified” sherry casks. Not all ex-sherry casks used in the industry today are of the twelve-month dormant variety. Rather, they are being “seasoned”–a process in which wine is being added or left inside them to give the ex-casks resilience.[6] That being the case, we have to examine whether the scotch is compromised from a kashrus perspective.

A seasoned cask, or one that has been dormant for less than twelve months, will impart beneficial taste to the whiskey. This opinion is shared by the Minchas Yitzchak, who says that using such casks to age scotch is akin to mixing them with wine–a view that is in line with the Rav’s position.[7]

A seasoned sherry cask which contributes to the taste of the aging scotch cannot be nullified. So how are we to understand how bitul, nullification, works in the case of aged scotch?

To properly understand nullification, one needs to know that the ratio of wine in the final product must be less than 1:6 (i.e., one part in seven). The salient question is, how much wine is actually absorbed in an ex-sherry cask? To arrive at the correct conclusion, Rav Heinemann provides three important observations:

1. Casks are combined: Most scotches–single malt or blended–are aged in a combination of ex-bourbon and ex-sherry casks. The amount of product aged in ex-bourbon casks is subtracted from the total. That leaves only the portion aged in ex-sherry casks to figure in the calculation.
2. Wine is not fully absorbed: While the wine ages in new sherry casks, the taste seeping into the staves of the casks is only partially absorbed. This is evidenced by observing the staves once the casks are emptied: the purple color will not have penetrated the entire stave. Even though whiskey is considered to be a davar charif capable of transferring the taste of wine to an ex-sherry cask, the partial absorption allows for the halachic nullification of any non-kosher wine taste into the final aged product.
3. Water is added: To achieve the desired proof (i.e., the percentage of alcohol in the final version), the scotch is diluted with water.

These are three significant factors that contribute to the bitul threshold, thereby nullifying the wine taste.

There is, however, another factor to permit the scotch. This is a concept known as zeh v’zeh goreim–literally, “this and that caused the change”–that applies here. According to this principle, when two elements work in tandem to create a desired outcome, and if the outcome would be less desirable absent the partnership of the two elements, the product resulting from the combined effort is permitted.[8]

In our scenario, it is both the tannins inside the wood of the cask and the sherry imbibed by the staves which impart the taste to the aged scotch. Each one alone would not yield the same result. Zeh v’zeh goreim says that, in this case, the scotch is permitted.

The Nullification of Bitul: The Concept of Avida d’Taama

The factors elucidated above provide a sound basis for the nullification of ex-wine casks. But there are situations in which the nullification is essentially nullified, and the ex-casks are not permitted. This concept is referred to as avida d’taama, when there is an imparting of taste. This practice supersedes bitul. When they emphatically promote their sherry cask-aged whiskeys in their advertising, scotch makers are saying that their products have a special taste that is superior to ordinary whiskeys and which may be worth a higher price tag.

As a point of illustration, Macallan, one of the world’s most prestigious scotch producers, markets its scotch as being aged exclusively in sherry casks. In 2018, a bottle of 60-year-old Macallan 1926 whisky sold for over $1.1 million. This record was broken again in 2019, after a bottle of Macallan’s Fine and Rare 60 Year Old 1926 sold for $1.9 million.[9] Most recently, in September 2024, it released an 84-year old single malt produced in 1940 and long-aged in two different sherry-seasoned oak casks.[10] Its price is yet to be determined but is sure to be astronomical.

Distillers who use specific terms on their labels–such as, “aged in sherry casks,” “double filled,”[11] or “finished”[12]–are explicitly announcing an avida d’taama product. They are indicating that they intentionally imparted wine taste to their whiskey. Labels bearing these terms indicate that non-kosher flavor has been imparted into this scotch selection. These whiskeys are not acceptable for kosher consumption.

Raising a Glass to Kosher Spirits

It is always preferable for consumers to purchase scotch with reliable kosher certification. Before purchasing non-certified aged scotch, consumers should take special care to read the label on the bottle to ensure they are avoiding an avida d’taama situation. It is worth noting that many STAR-K kosher-certified scotch varieties aged in kosher ex-sherry wine casks have won awards in international scotch competitions. The kosher consumer now has a plethora of varieties from which to choose and which compromise neither on quality, taste nor kashrus. L’chaim!

STAR-K reminds readers of the importance of consuming alcohol responsibly and in a “kosher” manner.

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[1] Y.D. 123:16.

[2] Bourbon is a type of whiskey comprised of at least 51% corn and matured in charred new oak barrels at 125 proof. (See https://mybartender.com/articles/whiskey-terms/ accessed September 4, 2024.)

[3] Y.D. 135:16.

[4] Shulchan Aruch Y.D. 137:2, sh”ut 11.

[5] The reason is because after twelve months the cask loses its wine identity. This is similar to those who do not eat gebrokts on Pesach but permit eating kneidlach on the last day; the following Pesach, they may use the keilim used to prepare and serve the kneidlach because these keilim were dormant for twelve months, after which time the absorption of gebrokts on the dishes became nullified.

[6] See https://malt-review.com/2021/12/03/a-whisky-beginners-guide-to-sherry-casks/  (Accessed September 4, 2024).

[7] Vol. 2, 28:2.

[8] The classic case of zeh v’zeh goreim is something grown in a Petri dish. A non-kosher enzyme in the media serves to facilitate the conversion or fermentation process.  The conversion could have taken place sans the enzyme, but the result would have been less optimal. Through zeh v’zeh goreim, the result is mutar.

[9] See https://luxe.digital/brand/macallan/ (Accessed September 4, 2024.)

[10] https://robbreport.com/food-drink/spirits/the-macallan-time-space-oldest-single-malt-scotch-whisky-to-date-1235841671/ (Accessed September 4, 2024.)

[11] Double-filled means that the aged product is refilled exclusively into ex-wine (e.g., ex-sherry, ex-port, or ex-madeira) casks.

[12] Finished refers to a process in which the whiskey, after its initial maturation, is transferred to a different cask for a secondary aging period (and is another way of stating “double filled”).