This page aims to give you a basic understanding of spirit production, which in turn will serve to explain why particular products have their distinctive aroma and taste. If you are new to spirits or a seasoned spirit taster, I hope you find this page informative and useful.
Spirits can include any alcoholic drink that is distilled – whisky, brandy, rum, vodka etc. There are several steps involved in making a spirit, including: (1) making the wort; (2) fermenting the wort into a wash; (3) distilling the wash; (4) maturing the distilled new make spirit; and, of course (5) bottling/marketing the ready product.
The wort is basically the raw materials of the spirit. These raw materials are heated in water or pressed to extract sugars and flavour, and that liquid becomes what is known as the wort. Different raw materials are used for different spirits, which explains differences in flavour.
|Malt whisky||Malted barley (unpeated, peated)|
|Blended whisky||Malted barley and other grains|
|Irish whiskey||Malted and unmalted barley|
|Bourbon||Corn (at least 51%) and sometimes extra rye and malted barley|
|Rum||Sugar as the base ingredient, whether that is molasses, sugar cane juice or any associated by-products.|
|Brandy||Grapes (cognac, armagnac), apples (calvados), other fruit|
|Vodka||Anything (potato skins, rye, wheat, grapes etc) so long as it is then made (mostly) “neutral” by being “polished” through a carbon filter later. This distinguishes vodka, such as grape vodka, from brandy. Brandy has impurities for flavour whereas vodka is usually neutral and filtered (though traditionally in, say, Eastern Europe vodka did have flavour).|
Once the wort is filled with sugars, it is ready to ferment into a wash. Fermenting basically involves adding yeast to the wash at the right temperature, so that the yeast can convert the sugars into alcohol. So, for example, a whisky wash would be like a strong beer that has not had hops added to it. A brandy wash would basically be wine. A rum and vodka wash would be less interesting, but you get my drift.
Once the yeast has done its job converting sugars in the wort into alcohol, it becomes a wash. The wash is then distilled to extract its alcohol. Because alcohol evapourates at a lower temperature than water, it can be separated from the water by heating the wash to a temperature above 78.4°C but below 100°C.
There are many types of alcohol and not all are good. Here are some of the boiling points of the different alcohols.
Acetone 56-57 °C
Methanol 64.7 °C
Ethanol 78.37 °C
Water boiling point 100 °C
Acetic acid boiling point 118-119 °C
Hexan-1-ol 157 °C
The ones to watch out for are those that boil at the lowest temperature, acetone and methanol. They are poisonous and can lead to blindness and even death, but luckily they come out of the still first due to their low boiling temperatures. They are collected first as part of the “foreshots” and thrown out by distillers. The prize is ethanol, drinking alcohol. The distiller therefore needs to make “cuts” to get the most clean ethanol with tasty cogeners.
When it comes to cuts, the distiller needs to distinguish between the foreshots, head, heart and tail of the run. Foreshots come out of the still first and it is mostly acetone and methanol. It is real nasty to smell and highly toxic. This is POISON and is discarded. Then comes the heads, which is noticeable because it has traces of alcohol that smells similar to nail polish remover and it stings the nose. As the amount of ethanol flowing out of the still increases, the lovely juicy body of the spirit emerges in the form of hearts which is mostly ethanol. This is the sweet stuff, the nectar of the Gods – pure hearts is sweet, smooth, soft, expressive of the raw ingredients and just all round awesome (in my experience, the purist part of the hearts can be nosed and tasted at 90-95% with a smile). After a while, the hearts begin to fade into the tails, which smells very much like wet cardboard, baby sick, wet dog etc. It not poisonous, it just smells and tastes strange. For flavour spirits, such as whisky and brandy, the tails can provide some tasty congers and compounds which the oak cask can sort out during maturation. Remember, the idea of (modern, mass marketed) vodka is purity but what gives whisky, brandy, rum etc some of its flavour are impurities sometimes found in the tails.
Speaking of impurities, using a copper still is very important! Because most stills are made from copper, the vapour interacts with the copper which removes sulfides from the spirit while also accentuating esters and aldehydes.
The style of the spirit also depends on how many times it was distilled and the type of still used. Distilling a spirit more times tends to make it lighter and purer. Scotch tends to be distilled twice whereas Irish whiskey tends to be distilled three times and this gives it its signature smoothness and lightness. Similarly, Cognac is distilled twice while Armagnac is usually distilled only once. Perhaps more important, however, is the type of still used, its shape and whether it has a purifier to cause reflux and thereby inhibit heavier alcohols passing through the still.
The new make spirit is clear as water when it comes out of the still. For vodka, the cuts are important and then it is usually filtered through carbon to remove impurities. Whisky, brandy and rum makers want the flavours of the raw ingredients and some impurities so they do not usually clean their spirit in a carbon filter but they may filter or chill-filter it to get rid of some haze etc. For producers of “flavour spirits” (whisky, brandy, rum etc) “cleaning” is done by an oak cask/barrel.
Oak is porous, which means it soaks up the spirit and during this interaction the new make spirit draws out flavour compounds from the oak. There are hundreds of flavour compounds in whisky, because the oak either gives it flavour or alters compounds in the spirit. The oak is also most often charred, which means it acts in a similar way to carbon and soaks up some of the nasty compounds remaining in the new make spirit. This is why I like to think of maturation as “cleaning” a flavour spirit, as well as giving it flavour and character. A simple way of visualizing it is as follows: when it is warm the pores in the oak expand and soak up whisky, and when it is cold the pores contract and squeeze out the whisky. Over may days, summers and winters the whisky gets “treated” by the oak.
There are also four main types of oak:
- French oak;
- European oak (such as Spanish oak, Hungarian oak etc); and
- Japanese oak.
American oak tends to be strong in vanilla. Bourbon producers need to use new charred barrels, whereas the vast majority of whisky producers (including Scotch) use used bourbon barrels to mature their whisky. French and European Oak have less vanilla, but tendto offer winy notes (port, sherry as the case may be), caramel, sticky date and Christmas cake. Brandy producers, such as in Cognac, use oak from particular forests while whisky and Scotch producers use barrels that have held something – usually sherry or port. Japanese oak is super porous and rarely used these days due to leakage problems, except to perhaps finish a whisky.
Despite what they say, size also matters. A smaller cask or barrel allows the spirit to mature more quickly, so if a whisky is matured or finished in “quarter casks” or “octave casks” then it may also have matured more quickly than it would have in ordinary sized casks. The reason? Smaller casks allow the spirit to interact more with the wood, and with that interaction comes more opportunity to draw out the character of the wood. Of course, a spirit can have its character hijacked by too much wood exposure and taste like a dry tree branch!
This does not however mean that you can hurry love! Making great whisky takes time. I have tried many “new world” whiskies that rely on “climate” and the use of small barrels to justify very short maturation times. Many of these just tasted woody to me, not mature. There is some research suggesting that the alcohol in barrels needs time to break down compounds in the wood, so it may not be enough to simply expose whisky to lots of oak. In addition, oxidisation (exposing whisky to oxygen) is also important to whisky maturation and this takes time. So, time really does matter.
Climate also matters. The climate in which a spirit matures is important, because the warmer the climate the most likely it is that the spirit will mature more quickly than in cold climates. Although warm climates make whisky etc evaporate at a high rate meaning more of it is lost than in cooler climates such as Scotland, the warmth also dilates the pores in the oak casks which results in increased interaction with the spirit in the cask. This in turn lets the spirit suck out more flavour and character from the oak.
Lastly, we all like pretty shine things. Call it vanity, but packaging contributes to the experience too.
There you have it. A short guide to spirit production. I hope you can now taste different spirits and whiskies and now have an idea whythey are different and what to look for. All the information you need is on the label.
Saluti / Sláinte / Cheers