Scotch Aged in Sherry Casks

SCOTCH AGED IN casks that previously held sherry presents a serious kashrus concern. Non-kosher wine (stam yeinam) is prohibited mi’d’rabbanan, and when wine sits in a cask for 24 hours, the flavor is absorbed into the wood through k’visha (soaking). Any whisky that is subsequently stored in that cask can absorb the non-kosher flavor.

Why isn’t this permitted after 24 hours have passed (eino ben yoma)?

Normally, when a vessel is eino ben yoma (unused for 24 hours), any absorbed flavor is considered pogum (deteriorated) and generally does not prohibit the food or drink placed in it. Wine, however, is different. Its absorbed flavor enhances the final product (nosein ta’am lishvach), so the leniency of eino ben yoma does not apply unless the cask has remained unused for an entire year. Furthermore, whisky is classified as a davar charif (a sharp beverage), which can draw out and intensify the sherry flavor from the casks, even after a prolonged period of disuse. This changes the status of the absorbed flavor from pogum to lishvach.

Is sherry nosein ta’am lishvach in whisky?

Some Poskim allow whisky aged in sherry casks based on the Noda BiYehuda (Mahadura Tinyana, YD 58), who argued that wine flavor absorbed into whisky through soaking is considered lifgam (unpleasant). However, modern whisky production complicates this leniency. Distilleries today pay premiums for sherry casks and market the sherry influence as a positive flavor, proving that a sherry cask enhances the whisky.

In addition, in another responsum (YD 67), the Noda BiYehuda rules that wine-based hard liquors made from stam yainam (non-Jewish wine) can impart a positive flavor, which would make those liquors prohibited. Since sherry is a fortified wine with around 18% alcohol, it may fall into the category of hard liquor.

Does bittul (nullification) apply?

If sherry imparts a positive flavor, we must then consider whether it can be botul (nullified). While stam yainam may be botul at a 6:1 ratio, as opposed to the usual requirement of 60:1, there is debate about how to apply the leniency. The Taz rules that the 6:1 leniency applies to all beverages, including whisky. The Shach, however, disagrees, limiting this leniency only to cases where water is placed into wine barrels; for whisky, he requires the standard 60:1 ratio. In practice, most contemporary Poskim follow the Taz and permit relying on the more lenient 6:1 standard.

There is a second debate centered around how much wine is actually absorbed into the cask. The Taz and Chacham Tzvi hold that only the outer layer (k’dei klippah) of the wooden staves absorbs wine, while the Shach, Pri Megadim, and Chochmas Adam rule that the entire thickness is affected. Practically, many adopt the stricter view, making bittul difficult.

The Ruling of the Minchas Yitzchok

The Minchas Yitzchok (1902-1989) permitted whisky aged in sherry casks based on two arguments. First, in most cases, there is at least six times, and often sixty times, more whisky than absorbed wine. Second, the imparted sherry flavor comes from multiple sources — the wood, wine, air, and grain — making this a case of zeh v’zeh gorem, where the wine alone is not responsible for the taste.

However, while this heter may work for blended whisky, where the enhancement from the sherry casks makes up only a small percentage of the finished product, it is likely not applicable to single malts. Single malts rely heavily — even exclusively — on sherry casks. In these cases, there is often not even a 6:1 ratio, so the leniency of bittul does not apply.

Moreover, since sherry casks are chosen specifically for their flavor, it becomes a classic case of milsa d’avida l’ta’ama (a forbidden substance intentionally used for its flavor), and bittul does not apply, regardless of the ratio.

Conclusion

OK Kosher does not certify Scotch whisky aged in sherry casks and does not permit its use in certified restaurants or catered events. We recommend avoiding sherry-aged Scotch altogether.

Whenever possible, one should purchase whisky with a reliable kosher certification. At the very least, one should look out for words like sherry, port, oloroso, Madeira, or terms such as double matured, finished, or European oak on labels — all of which indicate wine-cask aging. If none of these appear, one may generally assume there is no significant kashrus concern.