Thought for the Day: I Don't Drink Scotch Finished in Sherry Casks -- Executive Summary

Full disclosure, I prefer bourbon to scotch. In fact, I prefer a quality rye to both. Of course, though, I wouldn't turn down a good scotch. What's the difference between different whiskeys? A lot. But for our purposes here, just  know that they all get their beautiful color from being aged in wood casks; mostly charred oak, but there are some others for special purposes. To legally be called bourbon, it must be aged in a never before used American white oak cask. Bourbon has a bit of a bite, which comes (in part) from the tannins in the fresh wood. Scotch has a gentler flavor profile and, therefore, specifically wants to age in a used cask that has already had much of the tannins removed.

Therein lies the rub. Whence does one get used casks? Basically, from other, non-scotch, distilleries. Two favorites: casks from America that were used for bourbon and casks from Spain that were used for sherry. For a long time they just used whatever was expedient/cheap/available. Fine whiskey and whisky, however, is now big business and the casks used has become part of their marketing.

Enter sherry cask finished scotch; and bourbon and rye, but I don't think those are as popular. In any case, for the kosher consumer this is a real issue. Sherry, being wine, is a highly kosher sensitive ingredient. There are scotches, bourbons, and ryes finished in casks that held kosher sherry. Those, obviously, are kosher according to all. The issue is whether one can drink scotches made from sherry that was made by non-Jews and has the status of סתם יינם/their regular wine, which is forbidden by Rabbinic decree.

How could it possibly be kosher if a non-kosher ingredient is used in its production? Why ביטול/nullification, of course! This is your first clue that even if we do end of finding that the sherry finished whiskey is not forbidden, it is all built on some sort of ביטול.

Most kosher authorities rule definitively that sherry finished whiskey is not kosher. There is at least one authority who would allow you to keep it (and drink it) if there would be a large loss. R' Miller from Toronto, though, paskens that sherry finished whiskey may be consumed לכתחילה. This is based on the following four considerations:

1. The issur of סתם יינם is to put up a barrier to social mixing with non-Jews. That is specific to wine, not other beverages, even alcoholic. Since the wine loses its unique bracha once it is diluted to one part in six, it is reasonable to propose that the issur also goes away. That is, we only need to have six times as much whiskey as sherry to nullify it, not the usual sixty.
2. זה וזה גורם -- neither the wood nor the sherry themselves give the whiskey it's distinctive flavor profile, rather they work together. That takes away the problem that something that gives taste is never nullified as long as you can taste it.
3. No one can really taste the sherry. The smell of the sherry is certainly recognizable, and we all know that taste is affected by the sense of smell. There is no principle that smells need to be nullified.
4. We usually say the entire thickness of the walls of a vessel that stored forbidden liquid needs to be considered in the calculation of nullification, a principle known as חנ''ן. In the case of sherry casks, though, we can actually cut them open and see how far the sherry has penetrated. It is usually between a third and a half of the thickness; based on visual inspection of the discoloration.
   

Taking all that together, and using a typical size cask used in the industry gets you to a volume of whiskey that is 8 or 12 times the volume of sherry.

Personally, I am surprised by (3), as the experts themselves differentiate between nose and palate. On point (1), R' Moshe says that a בעל נפש should be stringent and require the usual dilution of 60 fold. Given that sizable selection of fine whiskeys with undisputed kosher status, I just don't find this is an area where I want to push the envelope of leniency.

For a deeper understanding, I highly recommend R' Niehaus's excellent sefer on the topic. It an be ordered here: Sherry Casks: A Halachic Perspective.