How is Single Malt Scotch Made?

How is single malt scotch made? At The Borders Distillery in Hawick, Scotland we make single malt scotch through the following production process.

Step 1: Malting

Now first things first, to make good Scotch Whisky you have to start out with quality malt. At The Borders Distillery we have two silos outside where we store our malted barley.

Malt refers to a germinated cereal grain, in this case barley, which has gone through a drying process known as “malting”. The malting process involves soaking barley in water to encourage germination. The watered barley wants to grow and sprout out, so to prepare for this it will produce enzymes. The barley wants to keep growing, but that is not what we as distillers want. We are most interested in the production of these enzymes, as they will be responsible for converting the starch in the barley into fermentable sugars, and more fermentable sugars mean more alcohol.

The malting process consists of soaking the barley in water and taking the barley out to aerate it. This process is repeated a few times to start the germination process and make the enzymes we need. Finally, we put it in a kiln where we heat up the malt with hot air to dry it out and stop the germination process completely. The malt is then delivered to our distillery and stored in two silos outside.

Step 2: Milling

From the silos the malt will travel into the mill where the rollers inside grind it up. Our ground up malt (aka grist) is composed of 10% flour, 70% grit, and 20% husk. The flour is very fine and highly soluble. The grit has most of the most enzymes, proteins, and starches we are after, and the husk which is insoluble but acts as a filter bed so we can drain out the wort. We want the mill to grind the malt to these ratios so that we can extract as many sugars from the malt as possible.

Step 3: Mashing

The grist will enter the mashtun and we will add hot liquor, a.k.a., hot water to it. The hot water will work with the enzymes in the malt to break down the starches in the malt into simple fermentable sugars. The two most important enzymes at work here are alpha-amylase and beta-amylase. Beta amylase operates best at 55-65°C. Alpha amylase works best at 65-73°C, so for this reason we add our hot water in three additions. The first addition is at 65°C, the second addition is at 77°C, and the third is at 86°C.

Once the malt sugars are extracted, the sugary liquid called the wort, is drawn off from the grain bed and is cooled and collected into a washback.

Step 4: Fermenting

The yeast is pitched into the washback. The yeast is very hungry, and will multiply by consuming the sugars in the wort and converting them into alcohol.

Alcohol and carbon dioxide are produced and heat is also generated in the fermentation. It will ferment for about 3-4 days until the liquid in the washback, now called the wash is about 8% abv. Then we can transfer the wash into the wash stills to be distilled.

Step 5: Distilling Single Malt Scotch

We know that alcohol boils at around 78°C and water at 100°C, so to separate as much of the alcohol as possible we will heat these copper pot wash stills to around 93°C. The alcohol evaporates and travels up, into the lyne arm and is turned back into a liquid in the condenser. It goes through the wash safe and is collected in the tank below. At this point it is called low wines and is 25-30% alcohol. There are still a lot of flavours in it that we don’t want, so to further concentrate and purify the low wines we will do a second distillation in the spirit stills.

During this second distillation, the distiller must know when to cut the spirit into the “heads”, “hearts”, and “tails”. The “heads” is the start of the spirit collection, whereas the “tails” is the end of the spirit collection. These two parts contain less desirable components. They will be mixed with the low wines and distilled again. The “hearts” is the most desirable part, and is what will eventually become our scotch whisky. Each whisky distillery will have their own cut points which will change the flavor of their whisky. As well, each distillery will have different shaped spirit stills.

Spirit Still Shape

The shape of the spirit still also influences the character of the spirit. You will notice that at The Borders Distillery our spirit stills have a bump. The low wines contain higher alcohols which are heavier and oilier. The heavier alcohols will rise up, but they cannot handle the sudden pressure change in the bump and will drop back down. This is good because we do not want those flavours in our final spirit. That is why the spirit we produce is more on the dry and elegant side.

Step 6: Filling

The spirit that comes out of the spirit stills is around 70% alcohol, but we fill our casks with 63.5% abv spirit. We dilute the spirit down to this alcohol strength by adding water to it. Then we can fill up the casks with this new make spirit.

Oak is the wood of choice for scotch because of its intricate chemistry. The oak barrels have been toasted/charred inside by a coopersmith. This charring brings out vanillin, tannins, and lactones in the wood, and caramelizes the wood sugars in the oak to give Scotch Whisky its flavour and colour.

New, never before used oak casks have a strong woody flavor, so most Scotch Whisky is matured in second-hand casks, casks that have been filled with something else previously. For instance, here at the distillery the majority of our spirit is filled into Ex-Bourbon casks. Ex-Bourbon casks impart more sweet vanilla and coconut notes and a lighter colour to the whisky.

Step 7: Maturation

Casks will be stored in a bonded warehouse where they will mature for at least three years and one day.

You might be wondering what’s up with the one day ? That’s something you’ll have to ask the lawyers about. Although I believe it has something to do with preventing distilleries from cheating and selling whisky before the 3 year mark is up. Anyhow, while we can legally call it Scotch after this time, distilleries usually wait 5+ years before releasing their whisky to the public. The release date is entirely dependent on how it tastes.

One matured, whisky is filtered to remove any debris, diluted with water to the correct bottling strength, and bottled. Please watch the video below which explains how single malt scotch is made.

Watch it on YouTube Below

Related Content:

• How to Drink Scotch Whisky Like a Boss