A Closer Look: Scotch Whisky

WHAT IS SCOTCH WHISKY?
Scotch whisky is a distilled alcoholic beverage, made exclusively in Scotland, from fermented grains, water, and yeast, and aged in wooden casks.

Single malt Scotch whisky is made entirely with malted barley from a single distillery that was aged in multiple casks, while single cask Scotch whisky is made from whisky that was aged in a single cask. Blended whisky is made from a blend of single malt and grain whiskies from multiple distilleries that were aged in different casks. Blended whisky accounts for the majority of Scotch whisky production.

HOW IS SCOTCH WHISKY MADE?
MALTING: Barley is steeped in water to induce sprouting, which activates natural enzymes that convert starches into sugars. The malted barley is dried at the end of the process.

MASHING: Malted barley (with other grains, depending on the desired product) is ground and mixed with hot water in a large vessel to extract starch from the grain and the starches are broken down into sugar by the enzymes to create a sugary liquid called wort.

FERMENTATION: Yeast consumes the sugars in the wort and converts the sugary liquid into alcohol.

DISTILLATION: The fermented liquid is heated to the boiling point of alcohol (173°F), which is lower than the boiling point of water (212°F). The alcohol evaporates, separates from the water and impurities, and is collected in the condenser where it cools and returns to a liquid state. The process is repeated, and the resulting product is called “new mix spirit,” which is 70% alcohol.¹ The liquid is then diluted with water to reach 60% alcohol.

AGING: The “new make spirit” is stored in oak casks for a minimum of three years. During this time, the wood of the cask interacts with the whisky and improves the flavors and colors. The longer the whisky spends in the wood cask, the more flavorful the whisky gets.
Virgin (new) oak casks are not recommended for aging whisky. The strong flavors from the wood can overpower the spirits, so the most common casks used in the industry are casks that were previously used for aging bourbon² or sherry wine³.

BOTTLING: At the end of the aging process, the whisky is usually blended (with whisky aged in a different type of cask, a different fill⁴, or, in the case of blended whisky, single malt and grain whisky from multiple distilleries), diluted with water to 40% alcohol, and bottled.

IS SCOTCH WHISKY KOSHER?
The “new make spirit” does not pose any kashrus issues. The age-old discussion revolves around aging the whisky in casks that were previously used for wine.

Non-kosher wine is stam yainam which is prohibited mi’di’rabbanan. Once it has sat in the cask for 24 hours, the wine has been absorbed through k’visha (soaking) into the walls of the cask. Once anything else sits in the cask for 24 hours, the new product is kovush and absorbs the non-kosher ta’am (flavor) of the wine. In general, there is a leniency that permits the product (after the fact) if the second soaking is not within 24 hours of the first, because the flavor is considered pogum, blemished, and does not impart a positive flavor.

Whisky aged in wine casks poses a kashrus challenge. Wine has a different din because the flavor is lishvach (a positive flavor) and the leniency of eino ben yomo—not within 24 hours—does not apply to wine. The casks need to sit unused for 12 months before being filled with a
kosher liquid, at which time the wine flavor is no longer a concern. In addition, whisky is considered davar charif (sharp food), and the sharpness of the davar charif is always considered lishvach, even if 24 hours have passed.

Some Rabbonim permit the use of whisky aged in sherry casks based on the following rulings: The Shulchan Oruch (Yoreh Deah 137:4) says that clean vessels previously used for stam yainam can be used to store water, beer, and other beverages. The Noda BiYehuda in Ma’adura Tinyana (Yoreh Deah 58) wrote that the same applies to whisky – one can put it in a vessel that absorbed wine through cold k’visha, because the wine imparts negative flavor (pogum) to the other beverage.

Others argue and say that applying the ruling of the Noda BiYehuda to Scotch whisky is difficult for the following reasons:
1. The Noda BiYehuda writes, in siman 67, that if a barrel had contained a wine-based hard liquor, which was made from stam yainam, the beverage might impart a positive flavor to the other drinks which would pose a kashrus problem. It’s important to note that sherry is fortified wine
and contains about 18% alcohol content, which is achieved by adding grape-based alcohol to wine that was 6-12% alcohol. Maybe fortified wine is considered an alcoholic beverage, which the Noda BiYehuda clearly prohibits.

2. In addition, it is difficult to argue that wine imparts a negative flavor to whisky. Companies are willing to pay much more for a custom-made sherry cask when they could be getting much cheaper bourbon casks, and they advertise the use of a sherry cask, so how can we say that wine imparts a negative flavor, as it did in the time of the Noda BiYehuda? (It is possible that whisky during the time of the Noda BiYehuda was completely purified to nearly 100% alcohol which is a different product than whisky today, which is only distilled to 70% alcohol, and maybe even the Noda BiYehuda would agree that wine enhances modern whisky.)⁵

Even if we are concerned about the absorption of the wine into the casks, there is another plausible reason to be lenient. There is a machlokes about how much wine was absorbed into the cask and according to the Taz and the Chacham Tzvi, only the outermost layer (k’dei klippah) of the container is considered to have absorbed the non-kosher flavor of the stam yainam. If we follow that opinion, there will always be sixty times as much kosher liquid inside the cask as the tiny amount of cask material that is considered non-kosher, and it should not be an issue. However, not all poskim agree with the opinion of the Taz and Chacham Tzvi. The opinion of the Shach, Pri Megadim and Chochmas Adam is to follow the opinion of the Issur V’Heter that we need to assume the cask walls fully absorb the flavor of the wine and calculate bittul accordingly. Many poskim follow the opinion of the Shach.

Once we understand the concern that wine can impart a positive flavor, there is a potential to apply the leniency of bittul. The general Halacha of bittul is that one needs sixty times as much of a kosher item to nullify the non-kosher item mixed in with it. Regarding wine vessels, however, the ratio changes to 6:1. While the Shach holds that this leniency only applies to water placed in wine barrels, the majority of poskim, including the Igros Moshe and the Minchas Yitzchok, follow the ruling of the Taz, who says that this leniency applies to any beverage.

The ruling of the Minchas Yitzchok (1902-1989) was accepted as the mainstream approach to sherry casks. He permitted the whisky for two reasons: Firstly, there is certainly six times (the ratio applicable to wine), and maybe even sixty times, as much kosher liquid as there is wood that absorbed the non-kosher wine. Secondly, he writes that the flavor of the wine is not tasted in the whisky; it’s a new flavor that is a combination of the wood, the wine, the air, and the grain, and therefore it can be considered zeh v’zeh gorem (the kosher and the non-kosher flavors combine to create a taste) and the wine is not generating the flavor on its own. If you can identify the taste imparted by the wine, then the wine—however little of it there might be—is considered a milsa d’avida letaima—something whose purpose is to add flavor, and it would never be botul, even in sixty times as much kosher liquid.

In recent years, there have been questions about the ruling of the Minchas Yitzchok and whether he was provided with an accurate picture of whisky production and aging methods. Understanding the history of whisky production can put these questions to rest.

In the time of the Minchas Yitzchok, almost all Scotch whisky available was blended Scotch whisky. Single malt Scotch, which is highly sought after today, was not available during that time.
When making a blended whisky, even when some of the whisky was aged in sherry casks, it would be an extremely low percentage of the blend and most of the whisky would be aged in bourbon casks. When calculating the total amount of whisky plus the added water there is almost always more than sixty times against the wood of the sherry casks.

This is different from single malt Scotch, which has a much higher percentage of Scotch aged in sherry casks. Because most of the blend is aged in sherry casks it is unlikely to have a ratio of 60:1 of the liquid versus the wood of the sherry casks, and in some cases, when the usage of sherry casks is extremely high, there might not even be a ratio of 6:1.⁶

The manufacturers of single malt Scotch aged in sherry casks specifically tout the benefits imparted to the whisky from the sherry and are clearly looking for the sherry flavor. Therefore, both aspects of the Minchas Yitzchok’s ruling still apply to blended whisky, but not to single malt Scotch aged in sherry casks.

It is always best to buy kosher-certified whisky, or at least to avoid whisky when the label mentions sherry, port, oloroso, Madeira, or any words that represent aging in wine casks such as, double matured, finished, or European oak. The company is advertising and charging a premium for these features. If those phrases are not mentioned, the assumption is that it does not contain whisky matured in wine casks in a great enough quantity for concern. Even though it is not the norm, blended whisky may contain a large amount of whisky matured in sherry casks so the label should be checked, just as one would do for single malt Scotch.

1 Whisky is only distilled to 70% alcohol, so the flavor of the grain remains in the whisky. This is different from vodka, which is distilled to nearly 100% alcohol.
2 The American Bourbon Act requires that bourbon be aged in new, charred American white oak barrels, also known as “virgin oak” casks. After one use the casks can no longer be used for American Bourbon and are sold for about $100 in Scotland. They are the most used casks for aging Scotch whisky due to the low cost.
3 Sherry casks are used because they add depth and richness of flavor. The usage of sherry casks began in the middle of the 19th century when empty casks from the southern England bottling lines were sold to Scottish whisky distilleries. The supply of sherry casks has dried up due to Spain passing regulations requiring all sherry to be bottled on its shores. Today these casks are made to order and cost about $1,500 each.
4 Casks used to age whisky for the first time are referred to as first fill, and then the cask is emptied and filled with new make spirit for a second time (second fill). Casks may be filled a third time (third fill).
5 Others will argue and say that once the ruling is that wine imparts a negative flavor to whisky, it does not make a difference what modern professionals say about the matter.
6 The casks are thick, and the average volume of wood for a 500-liter cask is 136 liters. The whisky is typically diluted upon maturation with an additional 250 liters of water to reach 40% alcohol, but even 750 total liters of the finished product is not six times greater than the volume of the wood (136 liters) if not mixed with whisky aged in bourbon casks. Single malt scotch is often matured in smaller casks, and those have an even higher ratio of wood to liquid.

Rabbi Hendel is a member of the OK Kosher Vaad HaKashrus.