Archive for Malting

Crystal Malt

I recently enjoyed one of my favorite blended Irish whiskeys: Bushmills 1608. No, it’s not 400+ years old! Distilling in or around the town of Bushmills has been going on for that long. In fact, the license to disil [sic] was granted to Old Bushmills Distillery in 1608, hence the name of the expression. Part of what is claimed to make Bushmills 1608 smooth is the eponymous name of this article: “Crystal Malt,” along with the grain whiskey and careful blending. But what is crystal malt? A malting process? A type of barley? A way of processing a particular type of barley?

I’ve often wondered about the amazing variety of single-malt Scotch whisky: So many expressions (on the order of thousands) from basically three ingredients (water, malted barley and yeast). It seems so simple, but no two whiskies are so close to each other as to be indiscernable. From what does this variety emerge? Well, like anything that appears simple, it’s not. Whisk(e)y is a natural product, made from naturally occurring ingredients. There is a lot of variability in the process, but people are ingenious: Distilleries manage to turn out products that reliably reproduce the previous year’s product — when they want to.

Water sources matter somewhat. Barley isn’t one kind of plant: There are lots of varieties. At least 6 types are used in the production of Scotch. And all barley within a given variety isn’t identical: Was the soil too high in Nitrogen? Too low? Too wet? Not wet enough? You get the idea. Was the growing season hot? Cold? Just right? Then there is the preparation of the malt: Did the malt get peated? If so: How much? Even if unpeated, was it processed the same amount of time at the exact same temperature? What was the barley’s initial moisture content?  Was the malt comprised of just a single farmer’s barley? The fingerprint of the malt is the foundation of the whole process.

The production of Scotch is heavily regulated as to the ingredients, their preparation and all of the production techniques, yet these significant constraints still allow enough flexibility for the thousands of expressions of single-malt Scotch whisky. Based on a cursory web search, crystal malt isn’t used in the production of single-malt Scotch whisky. But if it’s used to make beer, it can be used to make whiskey (I spell generic whiskey with 7 letters, whereas I spell Scotch whisky with only 6 letters in the word “whisky;” many other kinds of whisky adopt the Scotch spelling, but not all do).

All across America, and the rest of the world, there is a re-emergence of distilled spirits, including whisk(e)y. Late 2008/early 2009 episodes of the WhiskyCast podcast have included interviews with some of the pioneers of this new (and simultaneously not-new!) business. Micro-distilleries are producing beer-based whisky (Charbay, here in Northern California, recently made whiskey from a Pilsner beer!). These would not necessarily be single-malt whiskeys, but they would be a beverage distilled from a cereal grain-based beer-like substance, so technically they are whisk(e)y.

Crystal malt is available in a variety of colors, and they were heated enough that some of their sugars are caramelized after being converted from more complex starches to simpler sugars while still inside the barley. Once caramelized, the simple sugars are unfermentable. Remember: The fermentation of the mash is what creates the alcohol. Yeast is added which converts the simple sugars to alcohol. Since crystal malts contain no enzymes, they cannot (by themselves) be used to create a mash for fermentation. They can be added to a mash bill to sweeten it. Crystal malts also noticeably smooth the mouth feel of beer when they are part of the mash bill; this mouth feel derives from the more complex sugars that are present in the malt.

Strictly speaking, crystal malt needs no mashing, so you can make beer without needing to make a mash. The mash, if you recall, is when you add the grist (ground up malt) to hot water so that the enzymes from inside the barley can convert the starches to simple(r) sugars. Because crystal malt already contains simple sugars, a home brewer can go straight from grist to fermentation.

So crystal malt is a process: You stew green (undried) barley in warm water which activates the enzymes inside the barley. This is what normally happens in the mash tun when the grist (ground malt) is steeped in hot water. In the crystal malt process, the enzymes act within the barley, and when the barley is dried, the converted sugars crystallize (hence the name). The whole process of making crystal malt is outlined at this home brewing blog. After the crystal malt process is complete, you can make it into a grist and add water and yeast, which ferments the sugars as usual.

It’s clear that crystal malt is advantageous in beer production, since it lets home brewers skip the step of mashing. And anything that can be used to make beer can be used in the production of whisky (though not Scotch whisky).

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Diageo Malting Plant: Silo Collapse

I was sad to learn that the Port Ellen malting facility on Islay was damaged yesterday. Luckily no one was hurt, but hundreds of tons of barley was in the silo when it collapsed.

Grain elevators in the US mid-west frequently explode because of airborne dust which is highly flammable, even explosive. Presumably we’ll know in a few weeks what the cause of this silo collapse was; it could have been explosive dust, or perhaps a structural failure.

What’s a malting plant? Malting is one part of the whisky production process that is centralizable. Malting is the process whereby the barley is sprouted by wetting it and letting it sit, historically it was spread out on a large malting floor, for several days. The need for a large floor was why malting benefited from economies of scale, however modern malting has improved upon the floor malting which can be adversely affected by weather (variations in humidity, primarily). Malting is still, for the most part, centralized even though floor malting has pretty much disappeared.

Malting is how the whisky producers crack open the barley to expose the sugars to the yeast that will be used in the next phase of production. If the barley seed were sprouting in a farmer’s field, the carbohydrates inside the barley seed would be used by the nascent plant to provide energy for its initial growth. Whisky producers need those carbohydrates (sugars), so the plant can’t be allowed to grow beyond its initial sprouting. The sprouting process exposes the tightly locked complex carbohydrates and enzymes. To stop the growth process before it goes too far, the barley is heated and dried which stops the growth and preserves the sugar for the yeast.

The malting process involves both sprouting (germinating), then drying the barley. The drying is facilitated by heat produced by burning coal and/or peat, which may impart desirable flavors to the malt. Once the malted barley has been produced, it can be shipped to a distillery for the next phase of the production process, wherein the malted barley is ground and mixed with hot water, which facilitates the action of the enzymes which convert the complex carbohydrates in the powdered malt into simpler sugars that are palatable to yeast. If you are familiar with the production of beer, you’ll recognize much of this process. Once the yeast is added, it produces, over the course of several days, a weakly alcoholic solution at about 6-7% ABV (as the alcohol concentration is increased, the alcohol kills the yeast, which puts an upper bound on the amount of alcohol that the yeast can produce). The next step, distillation, concentrates the alcohol.

How does distillation work? It’s not magic. Alcohol is more “volatile” than water. This is a term that has specific meaning for chemists, and it basically means that alcohol boils at a lower temperature than water. If you have a liquid that contains some alcohol and some water, and if you heat it in a precisely shaped container (e.g., a pot still), the alcohol vapor can be induced to condense back into liquid form.

If the condensation process were allowed to reach equilibrium, e.g., in a vertical tube, the alcohol would condense on the walls of the cylinder (if it were tall enough) and drain back down to the bottom, from where it would be heated enough to evaporate again. The reason it condenses is that the tube is cooler as one moves farther away from the heat. No matter how tall the vertical tube is, some alcohol vapor will escape over the top. My sense is that this is why the pot still is bent at the top, so the whisky producer can contain the alcohol and control the rate and amount of condensation within the still.

Also, keep in mind that the vapor that goes up the tube is a combination of water vapor and other volatile chemicals that boil at less than the boiling point of water. Even if the liquid is only kept at the boiling point of alcohol, there will still be water vapor present in the atmosphere above the liquid, since water evaporates even when the liquid is less than 100 °C.

Per wikipedia: “The boiling point of the alcohol ethanol is 78.29 °C, compared to 69 °C for the hydrocarbon Hexane (a common constituent of gasoline), and 34.6 °C for Diethyl ether.” The initial condensate, then, will contain lots of other volatile chemicals that may have foul odors or tastes (these odors and tastes come from fusel oils and other chemicals associated with alcohol production that may remind one of paint thinner, acetone, etc. — you wouldn’t want to drink them!). The tough part at this phase of production is that the foul odors and tastes will be soluble in water or alcohol, so they may be difficult to separate from the more desirable esters and phenolic compounds that whisky producers may want to retain in the finished product.

Once the pot still (actually, a pair of stills) has effectively burned off the more volatile components, the refined alcohol is allowed to freely flow to the “spirit safe” where the amount produced is measured very carefully for tax purposes. The operation of the still involves the careful attention of the stillman who determines when the proper product is ready to be collected, and who knows when to cut off the production before the still runs dry.

The spirit is usually distilled at least one more time before going into oak barrels for aging. Bruichladdich has produced “X4” that is quadruple-distilled and due to the concentration being increased at each stage of distillation, the ABV of the final product was well over 90%. Some Scotch is triple-distilled, as is most Irish whisky. The initial alcohol concentration of the spirit that goes into the oak barrels is about 70% ABV. Then the aging process reduces that concentration as the alcohol gradually escapes the semi-permeable membrane that is the wood while the wood works its magic of imparting its flavors to the liquid. As long as the alcohol concentration remains above 40% ABV, the liquid in the casks can be bottled and sold as Scotch whisky, provided it’s also at least 3 years old and meets a slew of other technical requirements.

Now that I have written some basics about distillation, I will go into some more detail about types of distillation and explain in a bit more detail why distillation works at all.

A Fungus Among Us

Yeast is what makes essentially all alcohol. Beer, wine, whisky, vodka/gin, sake, tequila, etc., all get their kick courtesy of the humble yeast: A single-celled organism that is classified as a fungus. Seriously! The edible (well, drinkable) kind of alcohol is Ethanol (C2H6O). If you are a chemistry or biology geek, you will recognize that Ethanol plus water (in the correct ratio) can be converted into sugar through some cellular magic that combines some water with some Ethanol and yields Glucose (chemically: C6H12O6). The latter can then be readily converted to energy in the body, which is why alcohol has calories.

Yes, Ethanol is readily converted into sugar (Glucose), but the body loses water in the process, which happens in the liver. The water the liver needs to metabolize alcohol is pulled from the bloodstream, which is why hangovers are often associated with a dry mouth. One way to prevent this is to drink lots of water before bed. Aspirin also is rumored to work. The fact that the liver is the first stage in alcohol metabolism is why the liver is affected (adversely) by excessive, prolonged alcohol consumption. But never fear, alcohol (Ethanol) is produced naturally in the body and one of the liver’s many functions is to be able to metabolize alcohol, a need that far pre-dated the discovery of fermentation and distillation!

All of this because a lowly fungus is adept at converting sugar or other simple carbohydrates into Ethanol. I can’t find any examples of Ethanol being produced naturally, except via the action of yeast. And that’s the source of all the alcohol that most people (and many animals) love to consume. All the various forms of alcohol, be they beer, wine, distilled spirits, involve Ethanol production in which yeast acts on a solution of carbohydrates, typically simpler ones.

In the case of whisky, the barley contains the complex carbohydrates that would normally fuel its growth into a barley plant, but they are stored deep inside the seed and distillers must trick the barley into exposing them and the enzymes that can break them down into simple sugars. That’s key to the malting process. Another word for this is sprouting, except that normally when a barley seed sprouts it isn’t killed right away with heat from a peat fire. In malting, you need to stop the process at the right time so the plant doesn’t consume too much of the precious carbohydrates. That’s the drying, sometimes over peat, sometimes over coal. Then the dried malted barley is mashed, warm water is added, and eventually yeast is added once the enzymes from the barley have been induced to break down the complex carbohydrates into simple sugars that are palatable to yeast. This action of the yeast on the mash makes a beer-like wort that is allowed to come to about 6-8% ABV over the course of several days. Then this is distilled, which concentrates the alcohol. Multiple distillations may be used to achieve higher concentration of Ethanol per unit volume. Scotch is, IIRC, usually distilled twice and put into barrels at about 70% ABV. Over time, the alcohol escapes and the barrel strength is reduced to no less than the legal minimum of 40% ABV. To be called Scotch, the final product has to be at least 40% ABV.

Sorry for the rambling post, but I thought it would be fun to give credit to the lowly yeast, without which this blog would not exist!