Tom Macy's Liquor Guide: How Spirits Are Made Flashcards
Overview of how spirits are made
Spirits are the product of distilled fermented beverages, such as wine and beer. So if you distill wine and beer, you will get brandy and whiskey, respectively. There are several categories of spirits, the biggest ones are gin, rum, whiskey, vodka, tequila, and brandy. What differentiates one from another is the base ingredient and the specific production methods used to make it.
The three primary stages of spirit fermentation
There are three primary stages of spirit production: fermentation, distillation, and post-distillation.
Ethanol vs. other types of alcohol
Chemically speaking, when one speaks of alcohol, it is referring to a class of chemical compounds including isopropanol, methanol, and ethanol. But in the context of beverages, when we say alcohol, what we’re specifically talking about is ethanol, aka common alcohol. Ethanol is the best tasting, easiest to process and safest alcohol for human consumption. There are a few other alcohols that factor into booze-making, such as methanol, but ethanol is what we’re really after.
The chemical structure of ethanol:
CH3CH2OH
The Base Ingredients of Whiskey
Whiskey: Grain, typically barley, corn, wheat or rye.
The Base Ingredients of Gin
Gin: Usually grain, but can technically be anything. It’s also infused with an assortment of botanicals, particularly juniper.
The Base Ingredients of Vodka
Vodka: Usually grain, can be anything, potatoes, for example.
The Base Ingredients of Rum
Rum: Sugar cane - usually in molasses form, but sometimes fresh cane juice of syrup.
The Base Ingredients of Tequila and Mezcal
Tequila and Mezcal: Agave
The Base Ingredients of Brandy
Brandy: Most commonly grapes, which are used for Cognac and the majority of aged brandies, but technically brandy can be made from any kind of fruit, in which case it will be called “apple” brandy, “apricot” brandy, “pear” brandy, etc.
ABV vs. Proof
ABV and proof are two measurements used to denote how much alcohol a spirit (any alcoholic beverage) is, and they essentially are the same.
ABV, Alcohol by Volume - This is the most common metric used. It refers to the percentage of a beverages volume is alcohol. So 40% ABV means that 40% of that bottle is alcohol (aka ethanol) and 60% of it is water and congeners. Alcohol used to sometimes be measured by weight as well, which would be labeled as ABW, though that is not as common anymore.
Proof - A spirits proof is simply double it’s ABV. It is expressed in degrees, so 40% ABV is 80º proof, 50% ABV is 100º proof, and so on. It is more common on labels in the U.S., and while it’s somewhat redundant as a measurement, the term “proof” is widely. People often describe something is high or low “proof”.
Why is it Called Proof?
Why is it Called Proof?
Proof used to mean something different than ABV. Initially, when the term It was conceived in England, proof measured the alcoholic density, or specific gravity, of booze, relative to its water content. On that scale, 100 proof equaled about 57% ABV.
This used to be measured by a test that involved soaking gunpowder with booze. If the booze was 57%, the gunpowder would still light. So if it ignited, that was “proof”, that the booze was 57%, aka “at proof”. Naturally, this test has been since replaced by more accurate (and less fun) methods of measuring alcohol strength.
But in its day, this gunpowder method of ensuring the strength of booze was very important for taxation purposes, as well as for ships that were carrying spirits, which was one of their primary means of transportation through the 16th and into the 20th century. Spirits traveling by sea were often required to be “at proof”, which is why today spirits that are 57% ABV are known as “navy strength”. You will still find navy strength gins and rums bottled at 57% ABV, or 114 proof by today’s measures.
The modern definition of proof is a descendant of a separate system developed in the United States in the 19th century which was based on alcohol percentage from the beginning, just using the word proof. As far as I can tell, proof is only printed on labels today out of tradition. That, and for the fact that 100 proof sounds way cooler that 50% ABV.
Geographic Indications and Designations of Origin
Geographic Indications and Designations of Origin
Many styles and categories of spirits possess a Geographic Indication (GI), meaning they can only be made in a particular country or region. For example, Cognac is a brandy that must be made in the delimited “Cognac region” of France, tequila must be made in Mexico, and bourbon must be made in the United States.
A common subcategory of GI is a Designation of Origin (DO). These are based on more the concept of terroir, meaning some facet of the surrounding environment, be it the soil, climate, water source, etc., contributes defining characteristics to the spirit that would be inimitable elsewhere. These also often include production guidelines. Broadly speaking, the difference is philosophical. A Geographic Indication simply protects a country/regions right to their intellectual property, whereas a DO insinuates that property would be impossible to replicate elsewhere. They are meant to ensure quality and maintain the integrity of the property itself. But the lines of truth here can be gray, more on that below.
Appellation O’origine Contrôlée (AOC)
Appellation O’origine Contrôlée (AOC)
Countries have their own internal systems and titles (often it’s simply Designation of Origin in their native language) that govern these certifications. Globally, they are all presided over by the World Trade Organization (WTO). One of the best-known examples is France’s Appellation d’origine contrôlée (AOC) system, aka “Controlled Designation of Origin”. It originated in the 1400s and set the benchmark for many of the DO systems that exist today. A vast array of French products are protected under an AOC. In addition to location restrictions, they also contain highly detailed specifications on production which are forcefully upheld. Cognac, Armagnac, Calvados and Agricole Rhum from Martinique are all spirits that possess AOCs.
Why is all this important you ask? Because it often the best way parsing out the differences between spirit categories and styles, even if it’s purely technical. This is especially great for nerds like me who is obsessed with classifying everything.
GIs and DOs Aren’t Everything
GIs and DOs Aren’t Everything
Keep in mind, since each country has a different system, the standards are not all the same. This is particularly true of DOs. For example, in Mexico, but only 9 states have a DO that allows them to make an agave spirit labeled as Mezcal, though fantastic Mezcal is made all throughout Mexico, even if it can’t be labeled as such. The reason for this has more to do with bureaucracy than terroir. This is all to say, the lines between these Geographic Indications can be blurry.
On that note, remember that while these systems can be helpful and often raise the bar for many categories, there’s no certification for quality. Just because something is made in a certain place in a certain way doesn’t make it better. Nor does the fact that it was made somewhere else make it bad. Take Japanese whisky, it was created in the 1930s in the image of scotch, and for decades was dismissed as a cheap imitation. But in the last 25 years, Japan has come to be recognized for making some of the best whisky in the world. Keep an open mind. Labels aren’t everything.
How fermentation works
Fermentation is the one and only way booze can be created, and that is why we love it. It occurs between yeast and sugar. Under the right conditions - moist and warm is ideal - the yeast will consume the sugar, converting it into energy and excreting out alcohol (specifically, ethanol) in the process. Yeast will keep on devouring sugar, and thus producing alcohol, until all the available sugars are consumed, or the alcohol levels reach around 15-17% ABV, at which point the yeast can no longer survive and die off. To get the proof any higher, distillation is needed.
In addition to alcohol, yeast also expels carbon dioxide, which is what bakers utilize these to make bread rise and some brewers still rely on for carbonation in their beer.
A third byproduct of fermentation is the creation of congeners, which are a catch-all term for a variety of organic compounds that supply alcoholic beverages with flavor. Because ethanol on its own doesn’t taste like much. Brewers, winemakers, and distillers rely on congeners and employ a variety of techniques to manipulate the kinds that are created while maximizing the alcoholic output.
Lactic Acid Fermentation
Lactic Acid Fermentation
- This is another type of fermentation that it has nothing to do with making booze. It occurs when bacteria in dairy, fruits, and vegetables, or muscles cells in animals, find themselves in an environment with no available oxygen. As a last resort, these organisms ferment any available simple sugars to use as an alternative energy source and create lactic acid in the process. This method is responsible for producing many of your favorite fermented food products like yogurt, pickles, and kimchi. It is also why your muscles are sore after exerting yourself while exercising.
Yeast
Yeast
Yeast is type of single-celled fungus, not a bacteria, and a relative of mold. It exists pretty much everywhere - there are yeasts floating around aimlessly in the air around you - and there are hundreds of different species. Some cause infection, some spoil food, and some make alcohol. Most alcohol-making yeasts are members of the Saccharomyces genus. The species S. cerevisiae specifically supplies the strains commonly known as brewer’s and baker’s yeast.
All types, or strains, of yeast behave differently in different environments. Which strain a booze producer uses depends on the results they are after. Some producers use natural or “wild” yeasts, meaning they allow whatever yeasts are hanging around nearby to do the job, though most carefully select yeasts, or cultivate their own strains for optimal control of the flavor profile they are after. For those producers, yeast is a closely guarded proprietary commodity.
Simple Sugars
Simple Sugars
Sugar is a type of carbohydrate that takes on many forms in nature. Yeasts can only digest what are called simple sugars which are the most basic type of sugar molecule, common examples include glucose, fructose, and sucrose, the latter we know as table sugar. Each of their chemical structures is across the page, which are relatively simple and short.
Simple sugars exist in virtually all fruits as well as some plants - notably sugar cane. Thus, most fruit will easily ferment on its own. If you lightly crush a few grapes and leave them in a loosely covered container, a few days later it will have turned to wine (this seemingly magical phenomenon is probably one reason why wine is affiliated with divinity).
Starches - Complex Sugars
Starches - Complex Sugars
Another form that sugar takes is as a starch, such as the ones found in grains like corn, rye or wheat. Of course, grains like these are relied upon are the bases of two of life’s most indispensable delights: beer and whiskey.
But grains will not ferment naturally on their own, because starches are too complex for the yeast to digest. They are made up of multiple simple sugars strung together, this is illustrated across the page by two the most common starch molecules: amylose and amylopectin. As you can see, the chains are much longer and more elaborate. To ferment grains, starch needs to be separated into smaller easily-consumable simple sugars first.
Breaking Down Starches into Simple Sugars
Breaking Down Starches into Simple Sugars
Starches can be broken down into simple sugars by enzymes called amylase or diastase. Accessing these enzymes is done in one of three ways: Malting, Koji, and Human Saliva
Malting
Malting
As luck would have it, many grains already contain the amylase necessary to break down their starches, it just has to be activated. This is done by a method called malting, steeping the grain in water which convinces it that it’s time to germinate. This effectively releases the enzymes and the breakdown begins. In nature, the purpose of these enzymes is to create food and energy for the growing plant. But before actual germination can take place, the grains are dried, encapsulating the sugars for fermentation.
The most commonly malted grain is barely because it contains the highest concentration of amylase. Barley that has been malted is called, as you might imagine, malted barley, or simply “malt”.
Malting is the traditional approach in the west for starch breakdown and is employed in the majority of whiskey and beer production.
Koji
Koji
Koji, aka Aspergillus oryzae, is a particular species of fungus that grows as a mold which contains the precious amylase. In this method, the koji is added to whatever is being fermented. This inoculates the batch with amylase and facilitates the breakdown.
This method was developed in the far east and is used to make sake, shochu, and other traditional Asian alcoholic beverages, though it can be used anywhere. Some Canadian whiskeys use koji, for example.
Koji fungus is usually cultivated with moldy rice cakes called “qus”. These often have yeast added to them so when introduced to a batch, the breakdown of starch and fermentation can happen simultaneously.
Human Saliva
Human Saliva
The third way to convert starch into fermentable sugars is the weirdest, but also the simplest. Chewing it! Human saliva contains the enzymes that do the trick. In fact, there’s a traditional drink in South America called Chicha which is made by chewing corn. Strange to be sure, but if I had no other option, I’d definitely I’d give it a shot.
It probably goes without saying that this method, thankfully, is not used for mass production.
Congeners
Congeners
As mentioned above, congener is an umbrella term for a collection of organic chemical compounds created during fermentation that supply spirits, wine, and beer with their particular flavors. Congeners make up for about 25% of a fermentation batch, the rest of which is alcohol (ethanol) and water. Some taste good, some taste bad, and some are downright toxic. Here are some examples of common congeners:
Methanol - A toxic type of alcohol that I like to call “bizarro ethanol”. Too much of it will make you go blind. Though it is ok in small amounts and is present in most spirits.
Acetaldehyde - A type of aldehyde (which is an oxidized alcohol) that has a sharp, metallic-y green apple flavor.
Acetone - A ketone that smells like nail polish remover.
Esters - A class of organic compounds that have varying fruity and floral aromas. You might say they are the brass ring of congeners. More on these below.
Sulfurous Compounds - A collection of compounds containing sulfur that have off-putting aromas of eggs and cabbage. Copper helps to strip these compounds out, which is why it is the go-to material for constructing stills.
Fusel Oils - A group of heavy, oily and generally unpleasant alcohols: butanol, propanol and amyl alcohol. Fusel is a German word for bad booze or rotgut. However, in small amounts, these can benefit a spirit’s body.
Acetic Acid - An acid that is best known for giving vinegar its familiar penetrating aroma.
A Bit More About Esters
A Bit More About Esters
Esters play an integral role in the flavor profile of many spirits so I thought I’d spend just a bit more time on them.
As I said above, esters are a class of organic compound that have varying fruity and floral aromas. Esters can be created during fermentation when an alcohol molecule and an acid molecule combine - both of which are plentiful of in a fermentation batch.
What I think is really cool about this is that two compounds with unappealing or even repulsive qualities can yield one that’s delicious. My favorite example is with the ester called Ethyl Butyrate, which I found described on cocktailwonk.com, a wonderful site for cocktail/spirits nerds, written by Matt Pietrek. In his words: “Ethyl Butyrate is formed when ethyl alcohol molecules combine with butyric acid. Butyric acid by itself has the smell of human vomit. But combine it with ethyl alcohol, and the resulting Ethyl Butyrate molecule smells of fruit and pineapple.”
So, human vomit flavor: eliminated. Pineapple flavor: created. Esters FTW!
Some Common Esters Found in Booze:
Some Common Esters Found in Booze: Propyl acetate (Pears) Octyl acetate (Oranges) Isoamyl acetate (Banana) Butyl acetate (Apple) Methyl trans-cinnamate (Strawberry) Ethyl cinnamate (Cinnamon)
Apart from the strain of yeast being used, what other methods have producers used which influence the result of fermentation?
Time
A shorter fermentation - 3-4 days - will generally create fewer congeners and, thus, a milder tasting product because there will be less time for congeners to develop and react with one another. On the flip side, longer fermentations - 5 days and beyond - will develop more intense and diverse flavors. In extreme cases, fermentation will go on for 1-3 weeks, or even longer. In these cases, bacteria will eventually begin to form which adds another congener producing variable to the mix that further expands the flavor range - for better or worse.
Temperature and Oxygen
Warmer temperatures will increase the rate of fermentation and thus the development of congeners, while lower temperatures stretch out the process offering more control of microbial growth and avoiding the potential for spoilage. Access to oxygen, or lack thereof, is also key in how the yeasts behave. The result depends on the strain of yeast and the style of spirit being made.
Fluctuating the temperature and oxygen levels will cause the yeasts behave in abnormal ways, producing different congeners, notably esters. This is commonly known as intentionally “stressing” the yeast. If done wrong it can ruin a batch, but if done right it can give spirits wonderful depth and complexity. Note, for beer-makers stressed yeast is typically a bad thing because all the congeners created will remain in the final product. Brewers call these off flavors. But remember, distillers have the ability to remove, purify, and/or modify, congeners during and post-distillation.
Additives: Backset, Bacteria, Dunder
Sometimes other ingredients will be manually added to a fermentation batch to cultivate congeners or maintain a certain environment. One example of this is famously done in American whiskey production where it is known as the sour mash process. Dead yeast cells leftover in the still from a previous batch, also known as the backset, are introduced to the next fermentation batch to creates an acidic environment which is beneficial to the yeast. This method is also traditional with many Jamaican rums, where the backset is called “dunder “. Dunder is sometimes stored in pits called dunder pits or “muck” pits which helps to cultivate acid-producing bacteria that can be turned into esters when the dunder is added to the fermentation batch. This latter technique yields some of the most unique flavors you’ll ever encounter in a spirit.
How distillation works
Distillation is the second major stage of spirits production, after fermentation. To distill something means to purify or concentrate it. In booze terms, this means taking a lower proof fermented beverage, such as wine or beer, and extracting only the alcoholic elements. This is easily done thanks to physics.
Alcohol (or more specifically, ethanol) boils at a lower temperate, about 175º F, than water, 212º F. So when a wine is heated to a temperature in within that range, the alcoholic molecules will vaporize while everything else remains a liquid. This alcohol-rich steam can then be collected and condensed back into a liquid, which will have a higher alcoholic content. Now it will be on its way to being brandy.
The Still: The Pot and The Column
The Still
The Pot and The Column
A “still” is the instrument used to conduct distillation. There are two basic types: the pot still and the column still. The pot still is the basic, traditional model - you can see a crude example of one above - while the column still is more industrial, complicated, and capable of much higher volume. Broadly speaking, pot stills are used produce spirits that are fuller - both in flavor and body - whilst column-distilled spirits are tapped for purer, lighter, and cleaner tasting spirits. One still better than the other - despite what some may claim. They have different strengths and serve different purposes. In fact, today many craft distillers use what’s called a hybrid still, which blurs the line between the two and offers benefits of both. On this page, we’ll examine how both stills work and how they differently shape a spirit’s flavor. But first, let’s look at where a spirit’s flavor actually comes from…
A spirit’s flavor is determined by its congeners.
A spirit’s flavor is determined by its congeners.
As explained on the fermentation page, about 75% of a fermented liquid, aka wash, is water and alcohol - both of which have no flavor. The remaining 25% is made up of a variety of organic chemical compounds such as alcohols, aldehydes, acids, esters, etc. These are collectively known as congeners. They are what provide alcoholic beverages with their flavors, both good and bad.
So while the central goal of distillation is to extract alcohol, an equally important task is navigating the congeners. A distiller needs to keep the ones they want and remove the ones they don’t want (and in the right amounts) to achieve their desired flavor profile. They can’t simply cherry-pick their favorites either. Congeners exist in different parts of a distillation batch, aka “run”. Distillers choose congeners by keeping certain parts of the run and discarding (or recycling) others. So distillation is not really about flavor creation, but rather flavor separation.
3 Key Points to Remember about congeners in distillation
- How the congeners are separated depends on the type of still being used.
Pot Still: By Time
Column Still: By Position
Congeners all have different weights and thus will vaporize at different temperatures during distillation. How they are separated and selected by a distiller is different in a pot still than it is in a column still. Harold McGee explains it best - as he always seems to do - in his amazing book On Food and Cooking: “in a pot still, it’s done by time. In a column still, it’s done by position.” I know that makes no sense now.
- A spirit’s proof coming off the still corresponds with its congener levels. And thus, flavor.
Higher Proof = Lighter Flavor
Lower Proof = Fuller Flavor
If a spirit comes off the still at a higher ABV it will be purer in alcohol (ethanol) and have relatively fewer congeners, meaning it’ll have relatively less flavor. On the flip side, a spirit that comes off at a lower proof will have retained more congeners and, naturally, be more flavorful. To two prime examples: vodka, which is flavorless by design, is typically distilled to 94% ABV, and cognac, which is jam-packed with flavor, is never distilled higher than 72.4% ABV.
To be clear, less flavorful doesn’t mean the spirit is inferior in any way, nor does more flavorful mean superior. It’s just a question of a spirit’s style. Note, this fact about proof does not apply to bottles of booze at the liquor store. Nearly all spirits are diluted with water after before they are bottled, so the proof on their label will not be an indicator of congener content.
- “Reflux” is key to quality distillation, and spirit purity.
Reflux is a phenomenon that happens inside a still. It refers to the repeated cycle of molecules (water, ethanol, and congeners) vaporizing, condensing, and vaporizing again before exiting the still. This cleanses the distillate of more congeners and leads to a greater extraction of alcohol, resulting in a more refined spirit. So the more reflux there is - as in, the more times this cycle of vaporizing and condensing is repeated - the purer and cleaner a spirit will be.
Different stills produce different levels of reflux, and all good spirits require some reflux. However, at certain levels the amount of reflux becomes stylistic choice.
