Knowing names and taste profiles of the subcategories of whiskey helps when choosing a bottle. Adding correct terminology helps when ordering a drink. Knowing how whiskey is processed illuminates why characteristics make it into the bottle. Every detail contributes or detracts from the finished product. Here’s an overview of how whiskey is made.
Based on local regulations or preferences for the desired finished product, one or multiple grains are chosen. Grain choice matters (corn is sweet, rye is spicy, etc.) and different grains react differently to fermentation and exposure to wood and oxygen.
Next, the grains might be malted. Malting is the process of soaking grains in water until they germinate then drying them to stop the growing process. Malting breaks starches into enzymes and sugars necessary for fermentation. Yeast feeds on sugars and one byproduct is ethanol (drinking alcohol). All included grains, or only a portion, might be malted. Enzyme additives to spark fermentation are sometimes allowed. The flavors are definitely different in malted vs. non-malted grain. Often a malt whiskey will display caramel or toast nuances. Although most whiskeys include malted grains, generally the term ‘malted’ is reserved for those made primarily from malted barley. Drying is accomplished by hot air or over a fire. In Scotland, peat is often burned to produce heat to dry malted barley and this peat smoke flavor is evident in the bottle.
The ground and dried grains are mixed with water and yeast in a large tank. This 'mash' is left to ferment for a few days and will reach about 10% alcohol content. Sour mash is akin to sourdough in that some of the current mash is reserved to add to the next batch to either provide more layers or keep multiple batches within a brand’s taste profile.
The grains may be separated from the liquid before or after distillation. This ‘spent grain’ is not used again for whiskey production, but makes a great feed for livestock.
Distilling is next. It removes some water to increase alcohol content and also removes some impurities. A column or pot still is used to evaporate and separate the alcohol from the other ingredients. Oftentimes the still is made of copper or steel with copper lining or piping since copper removes sulfur compounds. Column stills can remove more of the water and impurities, all but about 5%, actually.
Water (the water source and quality matters) is added to the distilled alcohol to achieve the desired alcohol by volume (abv) for the finished product.
The liquid is poured into wooden barrels, which are often charred inside, then left to age. Since the liquid pulls compounds from the wood, the type of wood, level of charring, barrel size, and aging time all contribute to the final flavors. About 25 years is the most improvement that wood can provide to a whiskey.
Generally whiskey does not change or continue to age once bottled. The age statement on the label refers to time in barrel. A whiskey that has been aged for 10 years in wood and released in 2000 will still be considered a 10-year whiskey in 2050. In a blended whiskey, the age statement refers to the shortest age time of the included barrels. Oxygen can still change the product, but mostly after the bottle is opened and only by a very small amount.
All whiskeys are filtered before bottling to remove obvious visible particles. Smaller particles might still cloud the liquid. Chill filtering is an extra effort to obtain a clearer product. Various particles separate at different temperatures. If the product is chilled, as in on the rocks, the cloudiness will increase. To avoid this, the whiskey is chilled out of the barrel to induce and filter cloudiness before bottling. The downside is this can alter characteristics. Often the filtering process is stated on the label, especially if it’s non-chill filtered.
Alcohol by volume (abv) is on the label to state which portion of the liquid is ethanol (drinkable alcohol). Abv is measured differently around the world which slightly affects the final number. Sometimes the required temperature at which it is measured is slightly different. It’s a whole explanation on partial molar volume that is better suited for a future article. For general purposes, the abv statement on the bottle is a close guide to the proportions in the bottle.
Proof statements vary even more. For instance, the US proof number is double the abv, the proof number in France is the same as the abv, and the UK uses a 4 to 7 scale. Proof began as a crude way to prove a liquid’s alcohol level for taxation (soaking gunpowder in the liquid in question and then trying to ignite it and sort of thing). It's not required on labels, but is often included for tradition's sake. Abv is the modern method of proof.
Whiskey makers must make many choices and the combinations of choices affecting the finished products are endless. I hope this three-part series helps you find whiskeys you love.
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