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A Whisky Beginner’s Guide to Sherry Casks

Remember the first time you went to an Asian restaurant? You got the menu and went straight to the drink section, like a serious alcohol connoisseur would. Then you read: Baijiu, Mijiu, sake, Shōchū, soju, Umeshu… Wait. What are these spirits? They are all rice wine, right? Or not?

If you have ever found yourself in this situation, you’ll likely empathize with how confused I was when I started drinking whisky. The inconsistent labeling practices did not help this Chinese girl at all! Case in point: I used to think Sherry, Oloroso, and Pedro Ximénez casks are three completely different things. It took me some careful research to realize that Sherry is a category of Spanish wine and that the Sherry casks used in whisky aging may have never held Sherry (just like Le Chiffre’s Montenegro poker tournament in Casino Royale was never filmed in Montenegro)!

In my defense: of all the things I ate and drank as a young adult, grape wine just didn’t make the list. Cultural differences have presented a lot of challenges to me in my whisky learning journey, especially in the very beginning when I didn’t know what I didn’t know. Although I’m lucky to be surrounded by many helpful malt mates, the fragmentation of information still makes learning very frustrating at times.

To restore your faith in my credibility, I’m sharing with you my version of Sherry Cask Bootcamp. Just so you know before you proceed: I don’t have certificates in WSET Level 1 or 2 or 3. Nor do I have any formal training in the whisky industry or close industry contacts. All I have is five years of PhD training; I’ve channeled those research skills to pursue my passion for whisky. Oh well, that’s all just a nice way to “position” myself and “package” this article.

Plainly speaking, this is a summary of my study notes on sherry casks. It is written for those who are new to whisky, or have never set foot in the Macallan distillery. If you decide to read on, brace yourself! Pour a dram, because some parts can be very dry (sorry for the Sherry pun). To our sophisticated, longtime Malt readers: there is probably nothing you don’t already know. Feel free to skip to the end, where a review of an 11-year-old Edradour matured in Sherry Oloroso casks awaits.

Sherry: What This Chinese Girl Got Wrong (featuring A Cheat Sheet)

First things first, what is Sherry? Like Scotch for whiskies produced in Scotland, Sherry refers to aged wines produced in the wine-growing region of Jerez, Spain. It is worth noting that not all the wines produced in this region can be labelled as Sherry. The production has to follow the specific processes set by Consejo Regulador (Regulatory Council). In addition, with the latest regulatory update, Sherry no longer has to be fortified (adding a distilled spirit into the wine). However, it still has to contain a minimum alcohol strength of 15 degrees.

When you dine at a restaurant and see labels such as Jerez (the Spanish word for Sherry) and Xérès (the French equivalent), rest assured that they all refer to Sherry. Just a friendly tip: don’t ask for “a glass of Sherry.” That’s where I got it wrong! Sherry is, in fact, a collective term for 8 different wine styles: Fino, Manzanilla, Amontillado, Palo Cortado, Oloroso, Pedro Ximénez, Moscatel, and Cream (which can be further categorized into Medium, Pale Cream, and Cream Sherry). These styles mainly differ in: (a) production location (Fino vs Manzanilla), (b) grape varieties (traditionally Palomino Fino, Pedro Ximénez, or Moscatel. The new regulation has included six more varieties), and (c) aging process (biological aging and/or oxidative aging). Of all the Sherry wine styles, six are most relevant to whisky. Therefore, I’ve made a cheat sheet for the characteristics of these six Sherry wine styles.

The Real Sherry Casks

To understand why people lament the quality of Sherry casks used in whisky maturation nowadays, let’s take a step back and talk about the OG. What are Sherry casks, really?

American white oak is often used to make barrels for the aging of Sherry, because it is widely available, provides good breathability, and is low in tannins. Now comes the surprise (at least to me)! Although new oak barrels might be used at the fermentation stage (a practice that has mostly been replaced by steel tanks), Sherry is actually aged in old, inactive oak barrels.

Unlike other wine makers who try to “arrange a perfect marriage” between wood and fermented grape liquid, Sherry makers want the oak barrels without the wood impact. Why is that so? It is said that wood tannins tend to inhibit florduring the aging process. Also, Sherry makers simply don’t want wood flavors and tannins in Sherry wines. To avoid that, Sherry makers commonly use 600-liter oak barrels (three times bigger than standard American Bourbon barrels) for a lower wine-to-wood ratio.

In addition, before an oak barrel is “qualified” for the job of Sherry maturation, it has to be first used to ferment grape musts or to age young fortified wines for a minimum of 3 years by law (but often much longer in practice). That means that by the time an oak barrel is used to age Sherry, the impact of wood has more or less been exhausted. In fact, Sherry doesn’t get flavors from oak barrels. Instead, it gets flavors mainly through oxidization. It might also soak up some aromas from the young fortified wines previously aged in these oak barrels.

Sherry Casks in Whisky Maturation

Now you know the specific requirements of oak barrels for Sherry maturation. You might think, like Bourbon casks, the Sherry casks used in whisky maturation are the oak barrels retired from Sherry maturation, right? Nope! Not even in the good old days! This was another revelation to me.

In the good old days, the Sherry casks used in whisky maturation were oak barrels used to transport aged Sherry from Spain to UK. Originally made from European oak, these transport casks had a capacity of 500 liters. Similar to the oak barrels for Sherry maturation, these transport casks were first used for fermentation or short periods of maturation, so as to reduce wood impact during transportation. Then, they were filled with aged Sherry and shipped to UK. Until the aged Sherry was bottled, it could stay in these transport casks for up to several months. During this process, a good amount of aged Sherry would seep into the wood pores. As you may guess, it didn’t make economic sense to ship these empty transport casks back to Spain. So, they were sold to the whisky industry for re-use.

Sadly, in 1986, the Spanish introduced a law dictating that all Sherry wines shall be bottled in Spain, effectively putting an end to transportation and transport casks. I should mention that, before this law, there were already practices to make barrels that mimic the effects of those Sherry-seasoned transport casks. But this law has, unintentionally, turned these practices into large-scale business operations involving three parties. Whisky distilleries specify their cask requirements – the wood type, the toasting level, the type of Sherry used for seasoning, and etc. Spanish cooperages produce new oak casks accordingly. Once they’re done, the new oak casks are sent to Spanish bodegas for Sherry seasoning.

The Certified “Sherry Cask” Guarantee Label

In 2015, Consejo Regulador registered the “Sherry Cask” brand and drafted a document to regulate the production of Sherry-seasoned casks for quality control. To obtain the “Sherry Cask” guarantee label, the production of Sherry-seasoned casks should meet the following criteria:

  • The cask has to be filled to at least 85% of the total volume, with a certified Sherry wine made by bodegas registered with Consejo Regulador.
  • The cask has to continuously hold the wine at the required fill level throughout the entire seasoning process. This means bodegas can’t empty the cask and re-fill it with other wines in between.
  • The minimum seasoning period is one year.

Well, we all can read regulations. What comes now is me reading between the lines. There are three factors that will affect the quality of a Sherry cask but are not specified by Consejo Regulador:

  • Age of Sherry: Although the wine has to be a certified Sherry, there’s no regulation about the wine age. Word has it that producers typically use 2-year-old Sherry wines.
  • Re-use of Sherry: Furthermore, there’s no regulation about how many times the same wine can be re-used for seasoning! In practice, it is often re-used for several times before being discarded or being used to distill Sherry brandy or Sherry vinegar. Theoretically, a cask seasoned with a “virgin” wine can be quite different from a cask seasoned with a re-used wine, as a re-used wine contains more wood tannins.
  • Transportation: There’s no regulation about how the casks should be transported, either. Should they be transported dry? Should they be transported with Sherry? How much Sherry should these casks contain during transportation? These are, again, up to whisky distilleries.

Whisky distilleries typically have a say in these factors when making an order. Or, at least, they know what casks they are paying for. But I guess such information is too wordy for the aesthetics of their fancy product packaging; and it takes them too much effort to put it online.

 

An Overview and Comparison of Sherry Casks

The Real Sherry Cask for Sherry MaturationTransport Cask for Sherry TransportationToday’s Certified Sherry Cask for Whisky Maturation
WoodAmerican oakEuropean oakBoth, although American oak is commonly used now
Volume600 liters500 litersTypically 250 liters (aka hogsheads)
Treatment before Its Intended UseUsed for least 3 years to ferment grape musts or age young fortified wines.Used to ferment grape musts or age young fortified wines for a short period of time.Seasoned with a certified Sherry wine (often 2 year old) for at least one year.
Implications for Whisky MaturationThese casks are rarely used in whisky maturation. Just forget it!Aged Sherry is absorbed into wood pores.Young Sherry is absorbed into wood pores.

Edradour 2008 11 Year Old Sherry Cask (The Whisky Exchange Exclusive) – Review

58.3% ABV. Distilled: 28th November 2008. Bottled: 8th May 2020. Cask Number: 372. £79.95.

Color: Dark mahogany.

On the nose: Wafting into my nose first are coffee candy, chocolate, cherried liqueur, and dried dates. Time reveals sweet beef jerky and mulled wine spices, alongside hints of red apple and leather. Water brings out gentle sweetness, with notes of banana walnut bread, hazelnuts, and licorice.

In the mouth: The texture is silky like chocolate fondue, minus the decadent mouthfeel. Opening on dried dates, caramel, and red apple. Mid-palate presents warming Christmas spices — it is more of an elegant blend-in than an aggressive take-over. With water, I get more fruitcake and brown sugar. As the whisky finishes, the taste gets slightly oaky.

Conclusions:

This is definitely not a Sherry bomb, but in a good way! The aromas are multi-layered and well-integrated. At cask strength, the liquid is more reserved with slightly muted flavors. A spoonful of water, or maybe two, significantly opens up the palate. Personally, I think it is a textbook example of a well-balanced Sherried whisky. Edradour has done it again, delivering us a quality whisky at a reasonable price. If you are looking for a Christmas present for a whisky lover, look no further!

Score: 8/10

CategoriesSingle Malt
  1. Patrick says:

    Hi there,

    thanks four your guide, very helpful for beginners. We love the Edradour Sherry Casks, as they are very smooth and some of them are very cheap like the ones from the unchillfiltered collection.

    Thanks and bye
    Patrick

    1. Alyssa says:

      Hey Patrick,

      Thanks for your comment! I’m glad to know that you find it helpful (the very purpose of this article!). I am a big fan of Edradour, too. Their quality is relatively consistent across batches and the price remains stable. Definitely a little gem as they say.

  2. PBMichiganWolverine says:

    Even though not a beginner, this was immensely helpful. I wish I had this years ago…would’ve saved a lot by knowing what profiles I shouldn’t buy. Thanks Alyssa !

    1. Alyssa says:

      I’m so glad to hear that even experienced malt drinkers like you find it helpful. That made my day!

      Personally, I think it is equally useful to know how bad whiskies taste. Then you really get to know how small issues, such as transporting casks dry or wet, may affect the quality of the drink. Hopefully, the bad ones are not too expensive though 🙂

    1. Alyssa says:

      Adam, thanks for reading the article so closely 🙂 It is actually a great idea to discuss the 10 different cask sizes, corresponding names, and how cask size affects whisky maturation in a future article!

  3. Francisco says:

    Very detailed and comprehensive article about Sherry itself (I’ve learnt some nuances I didn’t know about before) and the use of Sherry casks for aging whisky. Interesting to know about wine-to-wood ratio. It makes sense. Regarding the woods, in Brazil, for aging cachaça, besides European and American oak, are used some other woods like amburana, bálsamo and jequitibá, which provides a distinct flavor and color to this spirit.

    1. Alyssa says:

      Thank you for sharing your knowledge as well, Francisco! Wood itself is a big and fascinating topic to cover. I don’t really have a systematic understanding and deep insights about it yet. But just for fun, I bought several small casks with different wood types to play with some whiskies. A lot of trials and errors 🙂 But it’s good to learn and observe first hand how wood and whiskies react and interact with each other.

  4. Tim says:

    Thanks for the excellent article. I’ve been enjoying ex-sherry casked whiskies for over 30 years and found the information really interesting.
    I’ve been wondering for a few years now why I can’t seem to find many malts these days with that yummy oily sweet aged PX influence, and your very helpful explanation about the Spanish bottling law change in 1986 meaning that transport casks are no longer required seems to explain this well.
    I wonder if there are any distilleries with current bottlings still using Quercus robur (European) Oak which has held older Oloroso/PX sherry rather than something of an undoubtedly lower quality just used for seasoning purposes? I’d love to find a current bottling similar the classic Glendronach, Aberlour, Glenfarclas, Macallan etc. bottlings from the 80s/90s, as their modern bottlings (at least the ‘drinking price’ ones!) seem to have a thinner mouthfeel to me which I wouldn’t be surprised would be due to the sherry cask changes.

    1. Alyssa says:

      Tim, thanks for your kind words 🙂 Regarding your question, the answer is yes, there are current bottling that used older Oloroso/PX Sherry. I have been to tasting sessions, in which distillers specifically highlight this “strength” if that is the case with the whisky (sadly, I was too newbie back then to understand what it means. I wish I had kept a list). I watch Ralfy quite regularly, and he shares this info in his videos too if the casks have held older Sherry. But such info is often more of “insider knowledge” and not publicly available on packaging or websites.

    2. Alyssa says:

      I was chatting with a friend yesterday who knows Balcones very well. He said that Balcones has purchased several 80-year-old solera Sherry casks. It’s unclear when they are going to bottle the whisky matured inside these casks though. But I thought you might be interested.

  5. Lo says:

    Very interesting, it does make me wonder why some distillery’s (Glenallachie, Glenfarclas – Family Casks especially, Edradour, etc) seem to get far better results in terms of their sherry casks compared to others – is there a known reason within the industry? Is it pot luck (which seems highly unlikely)? Or is there particular process regarding seasoning which is somehow different/better etc? As you’d imagine, given the limitations distillers are facing, that there shouldn’t be such pronounced differences in terms of sherry impact and influence.

    1. John says:

      It’s a dirty secret that most of the industry tends to use “wet” casks. Wet as in the cask has residual sherry left in the barrels it’s filled with the whisky.

      Other distilleries like Edradour, I think, properly treat their casks. Hence the lack of sulfur which lets the sherry flavor be more noticed. Proper treatment included steaming casks and cleaning it with hot water. It removes the residual wine left in the cask during transit. Residual wine are left in the casks so they can keep the insides wet. A dry cask would result in bacterial growth within the cask.

  6. Cal says:

    Great article! I am wondering hoe protected the term “Sherry Cask” is. When a whiskey says “Bourbon” on it there is a legal definition that product must adhere to. Does the same apply for “Sherry Cask”?

    Thanks

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