Ein Destillationsgerät mit Alembik und Luftkühlung. Aus: Kräuterbuch des Matthioli, 1586

Following the Traces of Alcohol – With the Still to high-proof alcohol 

In the second part of our inter­view series “Following the Traces of Alcohol” we examine how a Still works:

What processes does the alcohol go through before it can be clas­si­fied as high percentage in the end? Our inter­view partner Kur Sartorius, initi­ator and leader of the “Schwäbisches Schnapsmu­seums Bönnigheim” (Swabian Hard Liquor Museum in Bönnigheim) shares his expert know­ledge.

Brüggemann­Alcohol: What exactly is a Still?

Kurt Sartorius: Let’s first have a look at a distil­la­tion itself. This process repres­ents a phys­ical separ­a­tion of two liquids. Water boils at 100 °C and alcohol at 78 °C. Consequently, when the liquid is heated, the alcohol evap­or­ates first. The prerequisite for such a process is the use of a lock­able vessel with an opening. This is where the pot still comes in. In it the mash is heated and brought to boiling. The alcohol-containing vapors are conducted to the cooler via the helmet and spirit pipe. There the vapors cool down and condense.

Only the cooler went through a series of devel­op­ments: air coolers, tube coolers, plate coolers or rod coolers are a few devel­op­ment steps. In Baden-Württem­berg, small distil­leries use vessels with a capa­city of up to 150 liters. Larger Stills can be found in Scot­land, for example. They hold 5,000 liters.

A distil­la­tion column is funda­ment­ally different. There the mash is pumped in at the top and runs down through various intensi­fying floors. Steam is intro­duced from below, which de-spirits the mash.

Brüggemann­Alcohol: With which substance is a burning process started?

Kurt Sartorius: The mash is the starting material.  It is an alcohol-containing liquid such as wine, fruit must or mashed fruit. Altern­at­ively, the starting material can also be obtained from grain or seed which requires an inter­me­diate step. This is because before distilling, the corn starch from the grain or seed has to be converted into fructose. The fructose is then fermented with yeast bacteria and thereby converted into alcohol.

Regard­less of which mash is used as the starting material, it only contains around 7 - 8% alcohol by volume. After the first distil­la­tion, the alcohol content increases to 20% by volume. Within a further cycle, the liquid, now drinking brandy, reaches 40 - 50 % by volume.

Brüggemann­Alcohol: How is high-proof alcohol made?

Kurt Sartorius: Each subsequent distil­la­tion process increases the alcohol content. That takes time and energy. Hence, distil­la­tion in the 19th century was very labor intensive. Thanks to new processes, it was finally possible to achieve a high alcohol content within one burning. At that time the use of ampli­fic­a­tion devices for the burning process began. Related construc­tions existed as early as the 16th century, but it was only with the inven­tion of the Pistorius basin in 1817 that high-proof alcohol could be produced.

Using the Pistorius basin, water cools the alcohol-containing vapors in a lens-shaped container. Water condenses at 100 °C, alcohol at 78 °C. There­fore, water condenses first and the alcohol remains in vapor form. In further Pistorius basins, the alcohol is forti­fied to around 70% by volume in one burning only. The steam is then passed through a cooling device, where it condenses and an aqueous alcohol solu­tion is ulti­mately created.

The ampli­fier devices that have been developed accel­erate this enorm­ously. The so-called bubble-tray is the most famous ampli­fier. Steam is passed through a bell to achieve the same effect: The water condenses and the alcohol remains in vapor form or evap­or­ates again. By connecting several bubble-trays in series a higher alcohol content can be achieved. Today sieve trays can also be used in the same manner.  At least 20 large bubble-trays are connected in series in powerful columns. Brügge­mann, for example, uses this process and produces alcohol with 96% alcohol by volume.


Picture Credits: left pric­ture: Bren­nblase, Helm und Geis­trohr aus Kupfer (c) Schwäbisches Schnapsmu­seum, right picture: Behrend Destil­la­tionsgerät mit Schlan­gen­kühler, Kurzge­fasste Anlei­tung zum prakt­ischen Bren­nereibe­trieb, 1885 (c) Schwäbisches Schnapsmu­seum

Brüggemann­Alcohol: What are the advant­ages and disad­vant­ages of the still?

Kurt Sartorius: The advantage of the pot still lies in the resulting quality of the end product. Espe­cially with fruit brandy, the aromas should be concen­trated in the alcohol. This works better in the still than in the column. The helmet also has the advantage that it collapses the foam of the mash in a way that it does not get into the cooler and thus into the distil­late. This would affect the quality and palat­ab­ility of the product. For this reason, grain or potato mash is primarily distilled in the column.

Brüggemann­Alcohol: Why is copper preferred for burning systems?

Kurt Sartorius: Copper is easy to work with or to bring into the required shape. The material proves to be a good heat conductor and very corro­sion-resistant. Still, the main reason for choosing copper is because of its ability to bind sulfur. Such compounds are in the mash and without the chem­ical effect of copper, these compounds would pass into the distil­late and affect its taste and quality.

If there is a person being entitled to call himself an expert of the history of alcohol, it defin­itely would be Kurt Sartorius, initi­ator und leader of the “Schwäbisches Schnapsmu­seum Bönnigheim”. 44 years ago, he completed his first spirit distil­lery and hence­forth intens­ively dealt with the history of alcohol. As a result, the distil­lery was to be turned into a local museum. Based on the recom­mend­a­tion by the state museum in 1985, the initial idea switched into the plan­ning of creating a special museum. The already existing huge diversity of regional wine museums forced Mr. Sartorius to open up a schnapps museum (opening in 1993). Today Kurt Sartorius has Germany's largest alcohol history museum collec­tion. In partic­ular, distil­la­tion tech­niques, the devel­op­ment of alcohol history and illicit distil­lery are among his areas of expertise. In 2020 the “Schwäbische Schnapsmu­seum Bönnigheim” was nomin­ated for the German Berlin Spirit Awards of Tradi­tion.

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