Although all single malt whiskey distilleries around the world use the same production process, each distillery has its own unique approach. Because of this, the identity of the distillery - its DNA - is reflected in every single malt whisky.
The distiller has many decisions to make throughout the flow, the key ones are shown below.
1. Barley
All Scotch malt whiskey is made from malted barley, water#1 and yeast, and although distillers prefer to use Scottish barley, it is not legally required to do so - it is smart to do so due to Scotland's unpredictable climate . Most distillers believe that barley varieties do not affect the flavor, but some believe that a variety called Golden Promise does give the spirit a different taste.
#1 Water
When making whiskey, distilleries require large amounts of pure, cold water. Therefore, it is crucial to find a stable water source. Most distilleries use spring water, but some also use lake water or even water from towns. Water quality may have a slight impact on fermentation efficiency, but distillers generally agree that water is not the main factor affecting the final flavor of whiskey.
2. Malting
A grain of barley is like a small packet of starch. The step of malting basically involves soaking the barley in water, telling it that the growing season has begun, and allowing it to germinate in a cool and humid environment. Enzymes are then triggered, converting the starch into the sugar the distiller needs. To ensure access to these sugars, he had to dry out the barley to stop it from sprouting.
Here comes the distiller’s first decision:
2.1 Kiln Options 1
Drying malted barley with hot air stops germination but does not add any flavor.
2.2 Kiln Options 2
The second option is to dry the barley over an open fire burning peat. This method adds a smoky aroma to the final product. Peat is a semi-carbonized plant that emits aromatic smoke when burned. The oil (phenol) in the smoke will adhere to the surface of the barley. Many Scotch whiskeys contain a small amount of peat smoke, and most smoked malt whiskeys Comes from island regions where peat has been the traditional fuel for domestic use and whiskey production.
3. Grind Wheat
The malt is sent to the distillery and ground into a coarse powder called cracked malt.
4. Glycation
The crushed malt is mixed with hot water at 63.5 degrees Celsius in a large vessel called a mash tun. As soon as the hot water comes into contact with the ground malt, starch begins to convert into sugar. This sweet liquid, called wort, is then filtered out of the porous bottom of the mash tun. This process is repeated two more times to extract as much sugar as possible. The last hot water added will be used as the first water for the next saccharification step.
4.1 Mashing Options 1: Clear Wort
By slowly pumping the wort from the mash tun, the distiller can obtain a clear wort, which makes it easier to create a liquor without strong grain characteristics.
4.2 Mashing Options 2: Cloudy Wort
If the distiller wants to produce a liquor that is not sweet and has nutty, grainy characteristics, he must quickly extract the wort and bring in some solid matter in the mash tank.
5. Fermentation
The wort is then allowed to cool before being pumped into a fermentation vessel called a fermenter, which may be wooden or stainless steel. Start fermentation#2 after adding the yeast.
#2 Yeast
In the case of Scotch whiskey, since the entire industry uses the same yeast, the yeast has no impact on the flavor of the whiskey. But Japanese distillers use different varieties of yeast to create their essential flavors in malt whiskey.
5.1 Fermentation Option 1: Short Time
During fermentation, the yeast will ingest sugar and convert it into alcohol (the liquid at this time is called juice). This process will be completed within 48 hours. If the distiller adopts the "short time" option, the final finished spirit will be It has more prominent malt characteristics.
5.2 Fermentation Option 1: Long Time
Longer fermentations (more than 55 hours) will cause esterification, producing lighter, more complex, fruity flavours.
6. Distillation Stage A
The fermentation broth is 8% alcohol by volume (abv) and is distilled twice in a copper#3 pot still. It is first distilled in a "juice still" to produce "low-alcohol wine" with an alcohol content of 23%, and then enters the "spirits still" for further distillation. This time, the distillate will be divided into three parts: head, heart and tail. Only the heart of the wine is retained for maturation. The head and tail are recycled and distilled together with the next batch of low-alcohol wine.
#3 Copper
Copper plays an important role in the flavor of whiskey. Because copper grabs the heavier element, distillers can extend or limit the time of the "conversation" between the alcohol vapor and the copper to create the style they desire.
6.1 Distillation Option 1: Short Conversation
The shorter the conversation, the thicker the resulting drink. It is easier to impart this quality using a small still and rapid distillation.
6.2 Distillation Option 2: Long Conversation
The longer the alcohol vapor talks to the copper, the lighter the final spirit becomes. This means that tall stills are more capable of producing lighter spirits than smaller ones. Additionally, letting the still run slowly will also lengthen the conversation.
7. Distillation Stage B: Condensation
The alcohol vapor turns back into a liquid after passing through a condensation device filled with cold water. Here again the distiller can choose how to influence the flavour.
7.1 Condensation Option 1: Shell & Tube Type
This is a tall column condenser with a large number of small copper tubes filled with cold water. When the alcohol vapor comes into contact with the cold copper pipe, it turns back into a liquid. Because of their large copper surface, shell and tube condensers help to "lighten" spirits.
7.2 Condensation Option 2: Worm Bucket Type
This is the traditional method of condensation, using a long copper tube coiled in a cold water tank. Because there is less copper contact this way, it tends to produce a heavier spirit.
8. Distillation Stage C: Cutting the Heart of the Spirit
When the condensed new spirit flows from the secondary still into the spirit safe, the distiller must separate it into three parts: head, heart and tail. The cutting points he chooses between the head, heart, heart and tail of the wine will also have an impact on the flavor.
8.1 Heart-Cut Option 1: Early
During the distillation process, the aroma of the wine changes. Initially lighter and more delicate, if the distiller wishes to create an aromatic whisky, he will cut the heart earlier.
8.2 Heart-Cut Option 2: Late
As distillation continues, the aroma deepens, becoming more oily and rich: smoky wine is what it is. If the distiller wants to make a thicker wine, he or she will cut the heart later.
9. Mature
The new wine will be diluted to an alcohol content of 63.5% and then placed in oak barrels for maturation. These casks usually once held bourbon or sherry. Divided into three periods:
- Exclusion Period: With the help of wooden barrels, the pungent new wine characteristics are eliminated.
- Aging Period: The new wine absorbs the flavor compounds from the barrel.
- Interactive Period: The flavors of the barrel and new wine blend together, adding complexity. Aging time, age of the barrel and oak type all play a role.
9.1 Cask Option 1: Bourbon Barrel
This type of cask is made from American oak, a species rich in flavor compounds, which imparts aromas such as vanilla, caramel pudding, pine, eucalyptus, spices, and coconut to the spirit.
9.2 Cask Option 2: Sherry Barrel
This type of cask is made from European oak, which imparts aromas of dried fruits, cloves, agarwood, and walnuts. European oak has a more saturated color and contains higher levels of tannins, contributing to a less sweet mouthfeel.
9.3 Cask Option 3: Secondary Filling Barrel
Whisky distillers often reuse casks many times. The more a cask is used, the less influence the oak has on the whisky. Second fill casks play an important role in highlighting the distillery's characteristics. In practice, most distillers mix whisky aged in three types of casks to add complexity to the flavor.
9.4 Cask Option 4: Changing Barrels
After using the first, second, or third cask options, distillers can apply "cask finishing" to give the whisky its final flavor refinement. This process involves transferring the aged whisky (typically from bourbon or second fill casks) into casks that previously held sherry, port, Madeira wine, or other wines with high residual activity for a short period of secondary aging. This imparts the characteristics of these active casks to the whisky.
10. Maturation: Time
Whiskey takes time to mature. Logically speaking, the longer the whiskey is in the barrel, the greater the impact the barrel will have on the whiskey, eventually overpowering the flavor of the whiskey and making it impossible to tell which distillery it comes from. A barrel with high activity can produce this effect quickly, while a barrel that has been filled many times will have almost no effect. The age marked on the bottle only indicates how long the youngest whiskey used in the bottle has stayed in the barrel, and cannot indicate the activity of the barrel. Older doesn't mean better.
11. Bottling
At this point, the whiskey is finally ready to be bottled, but there are still a few final decisions to make.
11.1 Does it need to go through condensation filtration?
This step will prevent the whiskey from becoming cloudy, but will reduce the taste.
11.2 Do you want to make caramel color?
Adding caramel helps standardize the color.
11.3 What is the alcohol content?
The law requires whiskey to have an alcohol content of at least 40%, and recently "cask strength" malt whiskey has become increasingly popular.