Q: Kvod HaRav,
Is single malt scotch whisky finished in wine casks kosher? Glenmoranige lists one of their single malts with this description: "Finished in Sherry butts after an initial maturation in ex-bourbon casks." No wine is added to the whisky, it only sits in casks that used to hold non-kosher wine.
If I am not mistaken yayin nesech is batel b'shesh. Obviously any wine left in the cask walls would be less than one in six. Do we hold by this and say the whisky is kosher or does ta'am k'ikar trump here and make the whisky non-kosher?
A: Dear Aric,
Your basic assumption is correct. The only caveat is that we must calculate based upon the dimensions of the cask itself and not our estimation of how much wine its walls absorbed. We treat the entirety of the cask as if it is non-kosher wine. Now, if we know for sure that the total volume of the casks is less than one sixth of the volume of the whisky that is finished in them, then that whisky is kosher.
By definition, the fact that we use the measurement "one sixth" rather than "one sixtieth" means that we are not concerned with taam k'iqar here. In other words, the possible or actual presence of wine flavor in the whisky would be irrelevant in this case.
UPDATE: A good friend informed me via email that I overlooked an important halacha in the Shulhan Aruch that addresses this case. In reality, even if the volume of the casks is greater than one-sixth of the whisky inside, the whisky remains permissible. This is because of a special leniency regarding non-kosher wine - the halacha is that the absorbed wine taste is automatically nullified by any non-wine beverage that is placed in the non-kosher wine vessels. The one-sixth ratio is only necessary when actual non-kosher wine becomes mixed into a kosher beverage.