Cognac, tequila, gin, vodka, whisky, rum…. an entire selection of bottles of various shapes and colors that rest on shelves behind the barman and that are generally called spirits. The common property of all spirits is relatively high alcohol content that’s usually achieved by distillation.
Let’s talk about spirits in general: about their origins, history, technology and the basis of their variety.
Since distillation is the foundation of spirits, we’ll discuss it first. In general, distillation is a process of separating components of liquid mixture via selective evaporation, followed by cooling condensation. The basic design of a still is a pot with boiling liquid and a cooling condenser that’s connected to the pot via tube. If two liquids in a mix (just a simplified model, usually there are much more) have different boiling temperatures, then we can separate them by heating the pot to the boiling temperature of the coolest liquid. The first substance will evaporate and transfer to condenser, where it becomes liquid again. The second one will remain in the pot. Of course, it’s difficult to completely separate two liquids this way, so, we usually imply saturation instead of complete segregation.
Distillation is used in many different areas. For example, oil is separated into kerosene, gasoline, diesel fuel, etc. based on the respective differences in evaporation temperatures of separate hydrocarbon fractions. Aromatic oils are also purified by distillation. The history of distillation usage goes into the mist of time, and the name of the first distiller remains unknown.
However, the spirit distillation came to human minds during historical times. For a long period of time, the priority in this innovation was granted to Jābir ibn Hayyān, the Persian scientist of the VIII century, who was also known in Europe under the name Geber. He was an author of many works in chemistry, alchemy, mathematics, medicine, astronomy, philosophy, and other disciplines. Since the XII century, his manuscripts were widely translated and used by European scientists. However, the acceptance of any new work by medieval scientific society was much easier if some eminent scientist been mentioned as the author of the work (well, modern scientific society isn’t that different). First glance is always at the name, and only then at the content. Respectively, apprentices and little-known scientists didn’t disdain to use some famous name instead of their own to improve chances of their works being noticed. The best choice was the name of some famous person of ancient times: it gave more confidence, and nobody would object. So, some Spanish, whose name remained unknown (now he is known as pseudo-Gerber), at the beginning of the XIV century wrote several chemical manuscripts, including one about distillation, and disguised them with the garb of translations of unknown Gerber’s writings. The truth was revealed much later.
The actual first recipe of distillation belongs to Magister Salernus (died in 1167) from the School of Salerno. Thus, Italia has a priority.
After its discovery, distillation became very popular among all chemists, alchemists, pharmacists and philosophers, who carried forward medieval science in monasteries of Europe. Some of them tried to find the fifth element using multiple distillations, later, from their philosophical ideas, came the actual word “spirit”. Mainly, however, spirit was used for medical purposes, since it appeared to be the perfect extract solution for many active herbal ingredients. That was the origination of elixirs, the predecessors of modern liquors. I had already written about one such liquor with long and interesting history.
By the end of the XV century, distillation crawled out of the walls of the monastery and began to spread out to the civil world. Spirit usage left medical boundaries far behind. People started drinking spirit just for pleasure. By the beginning of the XVI century, the methods of distillation had significantly improved. Application of multiple distillations for whisky began in Scotland and for vodka in Russia and Poland. Spices from East India and Caribbean Islands were used for taste improvement. During those times, Dutch, who controlled the spice trade with the help of their merchant marine, became the driving force behind the development of distillation. They needed “burnt wine” (brandewijn, future brandy) to fortify wine for sea transportation (wine badly react on to long-term sea transportation at hot climates), and to disinfect water for the same sea travels. Of course, it was more profitable for them to deal with distillers near sea ports, which resulted in distillery development in Jerez, Bordeaux and Cognac.
In XVII-XVIII centuries, most categories of spirits that we now know (cognac, vodka, whisky tequila and so on) had already existed.
By the beginning of the XIX century, the spirit production became strongly commercialized. Merchants throughout the world established brands by giving them names and guarantees of quality and consistency. Traditional pot stills no longer could cope with the required quantity of spirits. In 1897, new type of still, Coffey still, was invented. It had increased the speed of production, quality of purification and decreased the price. At the same time, Russia instituted the quality control on vodka, whisky production in North America came into bloom, and first cocktail era had begun. By the beginning of the XX century, all known types of spirits had existed.
Looks like the XXI century begins new era of spirit appreciation. The interest to spirits and to cocktails increases, and producers compete for quality and new tastes.
That was history, now is time for technology. If the base of any spirit is distillation, why do they have such different tastes? Why does France produce brandy, Russia vodka, Scotland whisky, Mexica tequila, and Jamaica rum?
The foundation of production of any alcoholic drink is similar for all: yeast converts sugar into alcohol.
Thus, the work scheme for spirit production is:
Raw materials – sugar solution – fermentation – distillation – maturation
Materials, presented in most, dictate the final product. South Europe with its vineyards and orchards traditionally specialized in brandy and eaux-de-vie. Grain North Europe produces whisky and vodka. Immigrants to the US and Canada preserve inherited tradition. The Caribbean and Mexico use sugar cane for rum and agave for tequila and mescal.
To begin fermentation, yeast should retrieve sugar from raw materials. It’s easy with fruits and berries, they initially have sugar in available to yeast form. With grain it is more difficult; it contains starch that has to be converted into sugar before yeast can start their work. Actually, a huge amount of starch in the grain exists not for distiller needs, but it is a food reservoir for initiation of germination, so, grain itself has ferments that convert starch into sugar (for energetic need plant uses sugar, the starch is just a convenient way to store it). So, the first step of grain preparation is malting – the germination of grain in order to convert starch into sugar. The same principle as in brewing. There are two approaches in grain preparation. First, all used grain can be malted. Such approach is used for malt whisky and some rye whisky. Second approach is thermal processing of most of grain, resulting in hydrolysis of starch, which breaks it into smaller polysaccharides. After the addition of small amount of malted grain or even pure enzymes, the process would be completed. The selection of approach determines the taste of the final product.
The next step is fermentation. A simplified understanding of this process – combine yeast and sugar together to get ethanol as a product. However, here we talk about a drink that has a complex taste, and not the spirit that’s made for technical use. It means that not only ethanol important, but also other substances that yeast produce (in smaller quantities than ethanol): various heavy spirits, esters and phenols. Actually, these components determine the taste of a product. The diversity and amount of aromatic substances depend on raw materials and on time and temperature of fermentation (longer fermentation yields more additional products). The manufacturer selects the fermentation characteristics depending on the expected taste of a product.
The result of fermentation is a liquid wash with 6-10% abv strength. Now we need to remove most of the water from it and some undesirable impurities, thereby increasing concentration of ethanol and aromas (aromas in our case are mixes of spirits, esters and phenols). The boiling temperature of water is 100C, ethanol – 78.3C. Boiling temperatures of aromatic components can be little lower or higher than ethanol’s. With the help of this differences in temperatures we decide which elements remain in our future drink, and which not.
There are several types of stills used in distillation. Let’s see how a simplest pot still, which only existed until the XIX century and is actively used nowadays, really works.
A pot still is a huge copper pot connected with a condensing system. One distillation in pot still is not enough to get a good product, normally two or even three successive distillations are required. After the first distillation we have a product of about 23% abv. The main work happens during the second distillation.
Fill a pot still with a liquid wash and begin to gradually heat it. At the beginning of the distillation, substances with a low boiling temperature begin to evaporate. No need to collect them. The next part is an ester-enriched mix that gives floral-fruit aroma. This is called “head” of the product. The collection of the product starts here. The next part is “heart” of the product; it is mainly ethanol. “Tail” follows the “heart” and is enriched with heavy spirits, esters and phenols. These parts are usually collected separately and combined later. At what point to begin the collection of a product and when to stop depends on the desired properties of the product. Want a spirit with light floral aroma? Collect more heads and less tails. Desire a heavy saturated spirit with a complex aroma? Collect more tails and less heads. Unused parts circle back to the next round of distillation.
The taste of the obtained product depends on several parameters (apart from start and end points of collection): the material and the shape of a still, the distillation speed, reflux and the condensing system.
Traditional stills are made of copper. The important thing about copper is that it absorbs heavy components. That means that the taller the neck of the still, the lighter will be the product, and vice versa.
All components that didn’t go through the neck of the still condense on its walls and fall back into the boiling liquid. This phenomenon is called reflux. Reflux regulation affects the product aroma as well.
In 1827, Scottish distiller Robert Stein designed a still with a fractionating column. It was improved and patented by Irish Aeneas Coffey as the Coffey still. Nowadays, Coffey still is widely used, as well as other types of stills that are made up of fractionating columns. Coffey still consists of two columns, which are divided into multiple horizontal parts by plates with pores. Top of the first column (analyzer) connects via tube to the bottom of a second column (rectifier). In my opinion, the original Coffey still looks like two piles of copper pots with holes in bottoms. Hot liquid wash (90-94C) is slowly poured from the top into analyzer. At the same time hot vapor rises from the bottom of analyzer. The vapor heats the wash that causes fraction separation (by boiling temperature). Light fractions (spirits and esters) fly upward to the top of the column, the heavy ones (including water) fall to the bottom, where they condense. Hot vapors from the top of analyzer go to the bottom of rectifier where they begin to go up again via the holes in the plates. The rectifier is cold, so the vapors begin to condense on the plates. Substances with higher boiling temperatures condense on the lower plates; the ones with lower boiling temperatures condense on the higher plates. Thus, we have different substances on different plates. Lightest substances leave through the top of the column. Collect condensed liquid, combine required fraction and voila. Coffey still yields high spirit concentration (90-94%) and provides better control of fraction separation.
There are multiple variations of column stills, though, they all have the same principal of operation. For example, single-column stills are used for bourbon and Armagnac distillation. Three and multi-column stills are used for spirits that have to be as highly clean as possible (vodka, light rum, base spirit for gin).
There is a traditional still pot with one fractionating column on the photo. The photo made on one of distilleries in East Washington.
We now have product that is almost ready. At this stage it can be diluted to the required strength, bottled and be ready for consumption. As an example, for vodka or grappa it’s the end of the way.
However, many other products still require maturation in an oak cask.
Maturation consists of three overlapping stages:
-Unwanted components are removed either by evaporation (light components can go through pores in oak) or by binding with a layer of carbon (casks are charred).
-Various substances, extracted from oak, yield different aromas to the spirit. Each species of oak yields different type of aroma. Thus, American oak yields vanilla, coconut, spices and chocolate flavors. European oak yields flavors of dried fruits, cloves and incense. Likewise, any oak grants tannins and color.
-Finally, spirit’s own flavors and those that came from the oak interact and produce the third wave of new aromas.
The longer the maturation – the richer the palate.
Of course, maturation has a lot of nuances. New oak is more extractive than the used one; small cask does more extraction than the bigger one. Prolonged maturation in new oak brings too many tannins. And so on, and so forth. Thus, producers’ choice of the type of casks and time of maturation depends on their aims. For example, Cognac and Armagnac producers keep their products during the first year in small, new casks to saturate them with color and tannins. After that, they transfuse the spirit into huge and previously used casks, for longer maturation. Producers of Scotch whisky mature their products in several casks of different oak and different charring (all used), and then make the blend.
It were the main rules for production of any spirits. However, any kind of spirit has its own technology principles, rules of production and traditions. We’ll discuss them separately.
