In the article “What is Polish Vodka”, we mentioned that vodka can be made from virtually any plant ingredient – grains, fruit or even vegetables. But for vodka to be called Polish Vodka, it has to be made from strictly defined ingredients originating in Poland. But this is just an introduction to the fascinating story of how Polish Vodka is made and you will learn about the stages of its production below.
Just to remind you, Polish Vodka has to be made from potatoes or one of the five grains listed (rye, wheat, triticale, oats or barley), all grown in Poland.
Producing alcohol from one of these ingredients requires making sure that their starch is split into fermentable sugars. The chosen ingredient is therefore liquefied; that is, steam heated to a high temperature (at least 150 degrees Celsius). When heated, the starch liquefies, which allows its easy contact with soluble enzymes. During the process, the polysaccharide (starch) decomposes into fermentable monosaccharides and disaccharides.
Mashing is the process of converting the starch into fermentable sugars through contact with several amylolytic enzymes, each having a different specificity and optimal temperature of activity.
The liquefied product is placed in a mash tun, where it is cooled and mixed with the enzymes. Once the temperature of the mash drops to 32 degrees Celsius, pre-fermented yeast is added and the whole mixture is pumped into a fermenter.
Distillery yeast is then added to the sweet mash to start the fermentation of the sugars. The process of fermentation takes 72 hours and requires cooling in its primary stage. The main products of fermentation are ethanol and carbon dioxide. The fermented mash (known as wort) contains 7-11% Vol. of ethanol. The process occurs in a fermenter.
During fermentation, simple sugars contained in the ingredient or released from polysaccharides (such as starch) are converted into ethanol, mainly through mashing. This is accompanied by the formation of a number of other, often unwanted, compounds which, together with ethanol and unprocessed components of the raw ingredient, determine the chemical formula and sensory characteristics of the fermented mash. Isolation of the ethanol from the mixture is the final stage of the technological process of alcohol production, which is known as distillation. Distillation takes place in a distillation column (a stripper column), which can be up to a few dozen meters high.
Distillation is a typical thermal process, which consists of heating the mash to high enough temperature for the ethanol to evaporate and then re-condense once the vapour mixture is cooled. Apart from the alcohol, other compounds contained in the liquid also evaporate while heated, including some water. The liquid produced gradually achieves a higher levels of alcohol concentration; the end product containing 88-93% ABV. Therefore, the raw spirit produced by distillation is a mixture of many ingredients whose isolation from ethanol occurs in specialised rectification plants rather than in agricultural distilleries.
Rectification has a direct impact on the quality attributes of the vodka. It consists of removing all impurities which may affect the flavour and aroma of vodka from the raw spirit. Rectification is a similar process to distillation – it consists of using high temperatures to evaporate the raw spirit in rectification columns.
The process is carried out in state-of-the-art rectification plants. In practice, it is a process of continuously repeated distillation which converts agricultural distillate into rectified spirit of no less than 96% ABV. The spirit produced becomes the raw material used for the production of vodka.
Rectification plants usually consist of a four-column system used for hydro-selection and demethylising. The technological process for such systems consists of the multiple distillation of raw spirit.
The raw material is fed into the upper part of the hydro-selection column. Simultaneously, spent feints from the rectification column and process water are added to the top of the column. Adding such considerable quantities of water to the column dilutes the spirit to 10-15% ABV. Carrying out the process with such high dilution levels changes the volatility of most of the impurities in the raw spirit, which makes them float to the top of the column, where they get removed from the rectification system and transferred for further processing in the post-rectification spirit column.
The partially purified, diluted spirit is collected from the base of the hydro-selection column. Next, it is pumped into the rectification column, where its alcohol concentration is strengthened and all forerunnings and feints are removed. It is then transferred to the demethylising column. This is where the methanol is removed, along with any remaining foreshot compounds.
What leaves the system is a highly purified agricultural ethanol (rectified spirit). The same system can produce spirit which is almost entirely free of any chemical impurities, called neutral spirit, if the right processing conditions are set up. Depending on the processing parameters, the agricultural ethyl distillate produced through rectification can differ in purity, i.e. the content of by-products of fermentation it contains. Producers themselves establish the standards for each type of rectified product they use to produce vodka. The choice of the rectified product – depending on the type of the ingredient used for production and the content of by-products of fermentation – determines the flavour and aroma of vodka.
Mixing alcohol with water
The final stage of vodka production consists of mixing the ethanol with water, stabilization and, finally, several stages of filtration.
It needs to be mentioned here that the quality and origin of the water is another key element determining the quality of the vodka, next to the purity of the spirit. The water has to have a neutral pH and be crystal-clear. It is best if it is retrieved from deep underground aquifers or clear mountain springs. In order for the vodka to be clear, the water also needs to be demineralised and deionised before it is used in production.
The appropriate ratio of water to spirit produces vodka containing at least 37.5% of alcohol.
Filtration of vodka
The system of multi-stage filtration is also an important element, as well as the right filtration media. They are responsible for vodka’s ultimate smoothness and clarity. Vodka can be filtered through different minerals, charcoal or cellulose filters, which interfere the least with vodka’s organoleptic properties. It is the producer who chooses the type of filter.
The filtered vodka can finally be bottled, but before it ends up on store shelves, it has to pass all sorts of quality tests to be approved for sale. But that is a whole other story…