All distilled spirits follow roughly the same patterns in their creation and differ in five main areas; the materials they are made from, yeasts and fermentation, distillation, filtration and maturation.

Raw Materials

The most important ingredient in liquor is the most important ingredient is water. In a standard bottle of spirits more than half the content of the bottle is water added at some point after distillation. This means that it plays a massive part in the final taste of a product.

The production of Ethanol in all alcoholic beverages relies on the fermentation of sugars through the action of yeast.

There are generally four sources of sugar found in materials used for potable alcohol production. These are:

  • Natural Sugars – Found in all fruits and the basis of the production of alcohol in Brandies.
  • Grain Starch –These form the source for the production of Whiskies.
  • Plant Starch – The starch held in mature plants as energy storage. This can be further subdivided into Root Stores (sugar beet), Tubers (potatoes) and Stem storage (Agave)
  • Sugar cane and its By-products

Each of these sources requires different processes to prepare for fermentation and should be treated separately, even though the end product can end up very similar.


One of grain’s characteristics is that it has insoluable starch and unfortuanately for the production of alcohol this insolubilty of starch is a major issue. Producers get around this with a process known as Malting. Malting involves first soaking the grain, then storing it at the correct temperature for germination. If the conditions for growth are correctly mimiced the enzymes in the grain begin to convert the starch. The process of growth is arrested by heating to denature the plant just as it begins to produce a shoot and the starch has all been converted. These denatured grains are then ground and ready to begin fermentation when suspended in water. Malting adds levels of flavourto the spirit. This malted grain used to be the basis of all grain based spirits and is still used in Irish and Scotch whiskies, and as starter in the manufacture of Bourbon and other American whiskies but has been superceded in the production of vodka.

When the grain has reached a level of germination that indicates the full conversion of starch the process is arrested by heating. In Irish whisky, Bourbon and other spirits this is done with indirect heat, often steam, whereas in malt whiskies the malt comes into contact with elemnts of the fire and smoke. This toasting process changes the flavour in two ways firstly how heavily toasted the grains are. This is used a lot to change the flavours of beer, but in Scotch the biggest effect comes from the contact with smoke. The peatiness or 'peat reek' of Scotch comes from this contact between the smoke from peat fires and the grain and is still obvious after distillation. This more than any other single taste demonstrates the importance of the raw material in a spirit regardless of the distillation accuracy.

The differences in various grains are represented in the spirits that they produce. Even in vodka the differences between rye, wheat and barley is quite pronounced.
The four main grains used in spirit production are Barley, Wheat, Rye and Maize.

The production of industrial alcohol.


The process of fermentation occurs naturally in various forms yet differs little. The strain of yeast uses impacts the fermentation so brewers and distillers carefully select and store the strain of yeast they intend to use, for its desired effects. A mention should be made of the sour mash process. This is where a portion of his unfiltered mash is distilled and added to the next batch to ensure correct growing conditions for the favoured yeast.

There are two types of fermentation and they are responsible for the different aspects of flavour. Aerobic and Anaerobic. These are often described in beers as top fermenting and bottom fermenting. They produce different chemicals and vary wildly in the speed of fermentation. Most spirits undergo a 40 -50hour fermentation but many ferment for as long as a week. The length of time is determined by the ratio of top fermenting (quick) and bottom fermenting (slow) yeast action. Most washbacks or fermentation tanks are sealed but those in North America are often open and gently bubbling. Fermentation is now normally carried out in stainless steel but some producers still use cypress or pine fermenters.


Distillation is the process of purification through the action of heating a substance to a gaseous form and then selectively condensing the required component.

Pot Distillation
A still is divided into three parts. The kettle or base is the vessel where the liquid is heated, the neck or swan neck is the hurdle over which the vapours have to travel and the lyne arm or line pipe is the path to the condenser and collection. The fermented wash is placed in the still and then heated. As the liquid starts to vapourise the distiller will collect the resulting liquid. This first distillation occurs in what is known as the wash still. It takes a distillate from 7-9% alcohol from fermentation of the raw materials and takes it up to around 21 -29 %. These liquids are known as low wines.

These are then placed in a second still, sometimes called the spirit still and are redistilled. The results of this second distillation are separated into three categories. The Heads or Foreshots contain high alcohols and aromatics and are recycled back into the system. The next part is the heart, the spirit that will actually be used, and the last are the Tails or Feints. These contain the heaviest components of the mixture and are generally also redistilled or discarded. The hearts of the distillation represent around 20-30% of the total run and it is the art of the distiller to pick his cut points to gain the best flavours. The liquid coming off the second distillation will vary between 52%(tequila) and 70%(whisky and cognac) ABV.  Some distillers, most notably in Ireland distil a third time. This allows a lighter and purer spirit of around 80% to be produced)

There are many factors changing the way a still works that have notable effects on the resultant liquid, namely, the size of still, the heat source and the shape of the neck.

The pot still requires on artistry of the master distiller based on both interpretation of technical data and also experience and as it is a batch process the still must be run, stopped and cleaned between batches. This is both labour intensive and time consuming and the limiting factor in volume production. The continuous still came around to get around both of these points.

Continuous Still
A continuous still is a double columnar device to take the guesswork and inefficiency out of the production of spirits. The system is designed to allow exact fractions to be removed from a sample automatically reducing the need for an experienced master distiller, and because the process runs continuously and can be recharged the inefficiency of a stop start operation is removed.

The continuous still consists of two columns, the rectifier and the analyser. The system uses heat very efficiently but quite confusingly. The initial stage involves heating the wash in the rectifier – in a closed system. This is the transferred in to the Analyser at the top of the column. The analyser has a series of copper plates with holes to allow vapour to rise and liquid to fall. The heated wash meets steam that is pumped into the bottom of the analyser. This steam strips the molecules from the wash and at each baffle plate a mini distillation is in effect taking place. The steam continues to rise along with the alcohol molecules it has stripped from the wash. This vapour then proceeds to the rectifier where it rises up through more baffle plates until it starts to condense. Each baffle plate can be accessed as each represents a fraction of the original liquid with a very specific condensing point. The still allows the removal of the high alcohols and the heavy elements are immediately separated in the analyser. This means that not only is there controllability there is increased efficiency. Most people consider the use of the continuous still primarily for white spirits and grain whisky but because you can choose the level of accuracy and define a range of fractions spirits including Armagnac and most bourbon can come from a style of continuous still, just the come off at less high proof.


Filtration in some form has been used since the earliest production of alcohol. At it’s most simple the concept of removing unwanted material from a given sample is the easiest way to improve the quality of a wine or spirit. There are two types of filtration: mechanical and chemical.


One of the most magical aspects of alcohol production happens in the months and years after distillation. Raw new make spirit is often known as Moonshine and is a harsh and uncomplicated product. It is then placed into oak barrels and after a period emerges as a brown, mellow and complex spirit. Probably the brandies of Cognac were the first to be recognised as benefiting from their time in wood but soon after followed the increase in both whisky and rum.

Barrel aging is a mysterious process relying on a variety of variables, and, when discussing the aging of a particular brand or sample it is often illustrative to look at the myriad factors that affect it. Aging in wood allows for four things. Oxidation of aromatic chemicals in an extremely slow and controlled manner; change in alcoholic strength due to evaporation; filtration in much the same way as activated charcoal works in other systems and addition of flavours that are originally present in the cask itself. All four of these processes are happening in every stored barrel of spirits in the world but it is the varying degrees of each process that creates the astonishing variety of final tastes. It is important to understand the following factors in the ageing process;

  • The Type of Wood
  • The size of the barrel
  • The age of the barrel.
  • The degree of char or toast.
  • The Climate.
  • The conditions of Aging, i.e The size, location and style of aging house can have effects on the aging process both by influencing the local micro-climate (even to the level of different areas of the warehouse) and also the level of efficiency and waste. The Angel’s Share is the spirit that evaporates away during aging and the levels of this are defined not only by temperature but also by local humidity, the more humid the smaller the loss.
  • The length of time.