Easy guide to Alcohol – explaining fermentation, distillation and spirits

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.What do you think of when you hear ‘cocktail’? James Bond and his ‘shaken, not stirred’ Martini? Maybe you think of big fruity drinks with small umbrellas, served poolside on a resort holiday? Or (god forbid) Tom Cruise flipping bottles in the famous oh-so 80s movie of the same name?

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The word cocktail has actually been in use for around 300 years and managed to evolve quite significantly during this time; starting off as the name of one type of mixed drink (“a stimulating liquor, composed of spirits of any kind, sugar, water, and bitters”, The Balance and Columbian Repository, 1806) it has moved to our more modern use of the word, as a general term that applies to mixed drinks that use distilled alcohol as a main ingredient.

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Alcohol you say?

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Yes, alcohol! If we’re going to look at cocktails and mixed drinks we first need to understand what exactly we mean by alcohol.

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Fermentation

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Let’s start at the beginning. The alcohol we use in mixed drinks is Ethyl Alcohol, or ethanol. (Not Methanol! – really, unless you want to be made blind this not a mistake you want to make, so no sipping the white spirit you find in your garage). We can create alcohol through the process of fermentation, which is the name we give to the chemical conversion of sugar into alcohol and carbon dioxide by yeast.

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I’ll try to explain this more easily using a simplified example of old-school wine production (as wine making is literally turning grape juice into alcohol).

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To make wine we press grapes to get grape juice, which contain naturally occurring sugars. Once we have this sugary grape juice we can transfer it into a container, such as a barrel, and the bacteria (yeast) that exists naturally will come along and start to interact with the sugars, eventually converting them into ethyl alcohol (ethanol) and co2 (and, most importantly in this case, wine!). So to put it simply:

“Sugar + yeast + time = alcohol + co2”

(Actual modern wine production is obviously much more complicated and scientific than this but that’s not important at the moment)

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Fermentation allows us to make beer (through the process of brewing malted barley), wine, cider (using the sugar in the apples, pears etc), and similar alcoholic beverages up to an ABV (alcohol by volume) of around 15%, before a number of natural factors come along and stop the process. This is all fine and good, but what if we want something a bit stronger? After all, that bottle of gin in your kitchen cabinet is certainly more than 15% right?

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That’s where distillation comes in.

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Distillation

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Distillation is the name of the process that allows us to separate the alcohol we’ve made through fermentation from the rest of the non-alcoholic liquid. This increases the ABV (from say 15% alcohol to something like 45% alcohol), while also changing the taste, flavour and removing the colour. Continuing with the wine example – if we distil fermented grape juice (wine around 10-15% abv) then we end up with Brandy (at around 40% abv). The more we distil, or the closer we get to pure ethanol, or 100% alcohol, the less of the original flavours from the fermentation remain – we end up with what we call neutral spirit, as it is relatively odourless and flavourless.

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How can we do this?

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Water and alcohol have different boiling points. You’ll probably remember from science class that at sea level water has a boiling point of 100°c. Alcohol on the hand has a boiling point of approx 78.4°c. This means that if we were to pour a mixture of water and alcohol into a pan and heat it up, the alcohol would boil and turn to vapour before the water, disappearing from our jug (and from our hearts) and into the sky.

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Luckily for us, over 1000 years ago humans developed basic tools called ‘stills’ which can make use of the different boiling points and collect the alcohol vapours instead of letting them fly off into the heavens.

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The first, and most simple, is the aptly named, Simple Still, or Pot Still.

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Pot Still

The pot still has two main components – the boiler and the condenser. In the boiler we place our mash (our fermented alcohol), which we then heat up. Once the liquid inside raises in temperature and reaches the boiling point for alcohol, the alcohol will change from liquid to a vapour and rise up through the swan neck and along the pipe into the condenser. As the condenser is not heated the alcohol will start to lower in temperature and eventually change back into a liquid again, and in the process we’ve now moved the alcohol while leaving (most) of the other liquid behind. There are some other compounds that come along for the ride as well, so distillers will break the liquid into cuts, with the heads and tails being the first and last parts of the distillation that can contain some pretty nasty compounds so need to be discarded. The body, making up around 80% of the total distilate, is what we will actually use.

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In reality one distillation will usually take us to an ABV somewhere around 25-45%, so in many cases we will do this whole process again (a second distillation) giving us a higher ABV again before we decide whether to bottle our alcohol (with some added water of course!) or rest it in vats or barrels.

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Column still

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A pot still is great as it allows us to boost the alcohol while retaining flavour from the original ingredients (remember that as the ABV increases you’re basically getting closer and closer to pure ethanol and losing flavour) but it’s not the most efficient way as its very much a stop/start process. Luckily for us around the time of the industrial revolution in the early 1800s the column still, or continuous still was invented. A column still lets us continue to add the mash while the distillation process is taking place, so the still can operate for far longer periods of time.

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The actual distillation is a little bit more complicated than the pot still but basically how they work is that the still is set up as two large stacks (or columns); one column acts as a still and one as a condenser. The still has a series of bubble plates, basically metal plates with small holes in them. The mash is added from the top and steam is forced in from the bottom. As the mash fights its way down through the holes the steam, moving up, heats the alcohol and seperates it from the mash, which allows us to collect just the alcohol vapors at the top. Through this process we can get really high ABV levels relatively quickly – up to around 96% (effectively making a odourless, flavourless, neutral spirit).

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Spirits

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The pot and column stills have allowed us to take our fermented mash and concentrate the alcohol. The result is that we have made spirits. Spirits is the term we use for distilled alcoholic beverages with an ABV >20%, with very little added other than water, colouring or sometimes a very small amount of sugar. You’ve seen spirits before – regular whiskies, vodkas, rums, brandies are all examples of spirits.

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Spirits can be made in pot stills (where flavour tends to be more important – whiskeys, cognac and similar), column stills (where we want a more neutral flavour, so vodkas, gins etc) or using both pot and column stills as a blend, for a sort of ‘best of both worlds’ approach (getting flavour from the pot still, but bulking it out with the cheaper to produce column distilled alcohol).

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Adding Flavour to spirits

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Once our spirit has been distilled there are still a couple of extra ways we can add flavour.

Oak Barrels

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The most well known method is by storing the alcohol in oak barrels. Originally used as a method of storage and to help with transportation, early distillers noticed that the alcohol they placed in barrels often ended up tasting much better than it had when it was first put in.

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Alcohol that has been stored in a barrel will take some of the colour of the barrel, so depending on how long it’s been stored, will be anywhere from a light, straw yellow to a deep dark brown colour (I should probably also note that many spirits allow colouring to be added to the alcohol so don’t always trust what your eyes tell you!). Along with the colour it can take on flavours; if you’ve tried aged whiskeys, brandies or rums you may notice flavours such as vanilla, or kind of woody, smokey tastes.

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Different brands will age their liquor for different lengths of time, anywhere up to and over 30 years. Because wood is porous a certain amount of alcohol will evaporate over this time, how much really depends on where the barrels are being stored. Humid conditions (say, rum in the Caribbean) will lose more to evaporation per year than whiskey stored in Scotland, with some producers losing up to 10% per year. This lovely process of losing alcohol is known as the angels share, for reasons I’m sure you can work out.

I’ll go more in depth about barrel aging and it’s role in specific spirits in later posts.

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Filtration

Another way we can change the taste of our spirits post-distillation is by filtration. Filtering the alcohol through activated carbon or something similar can help to remove contaminants or impurities that may be left over during the distillation process, but it can also remove some of the very precious taste (oh no!) so you tend to find that filtration is usually done on neutral based spirits, things like vodka or gin, where this isn’t so much of a problem.

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Flavoured Spirits

While they may seem like a new trend people have been flavouring spirits almost as long as they have been distilling them. One of the earliest and most common uses of distilled alcohol was as medicine and it was thought that flavouring alcohol with herbs, berries, flowers and similar could have a positive effect on your health (positive for that time, anyway!).

In terms of more modern products, people are often confused at the difference between flavoured spirits, such as Absolut Vanilla or Bacardi Razz, and liqueurs. The easiest way to think if it is the difference in the amount of sugar – flavoured spirits tend to have no (or very little) added sugar, so you’re basically tasting more of the actual spirit while liqueurs are much more heavily… sugared (if that’s a word).

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Also, while liqueurs tend to get their flavouring added to the spirit after distillation, some (but not all) flavoured spirits actually get their flavour during the distillation process, by putting the flavour (whether its raspberry, lemon, whatever) in with the mash during distillation. This gives a softer, and perhaps more subtle flavour than adding in the ingredients post distillation as you would with liqueurs.

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An example of spirits flavoured during distillation are most good dry gins.

Brands like Beefeater, Bombay Sapphire and the like take neutral spirit (so flavourless, odourless alcohol around 95% abv) and place it in a still along with juniper berries (the main flavour with gin) and other ‘botanicals’ (which is a fancy way of saying the ‘other ingredients’ in the gin, herbs and spices if you like). They then re-distil the neutral spirit and botanicals and the result, known as distilled gin, is the light, floral smell and taste we see in most of the good brands made today.

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It’s important to understand the difference between flavoured spirits and liqueurs when making drinks as you’ll end up with very different drinks if you substitute flavoured spirits for liqueurs, or vice-versa. Experimenting is good; but destroying, not so much!

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And that’s it for spirits! Quite a lot to take in but hopefully it makes some sense; there’ll be a follow up covering liqueurs coming soon so keep an eye out for it (or join the mailing list at the top of the page or like me on Facebook to make sure you don’t miss out).

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Let me know if you have any questions or comments.

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/ David