How Proof Affects the Flavour of Your Dram

Are you someone who likes their whisky to come in at a whopping cask strength, adding water and assessing the different flavours as they arise? Or are you someone who appreciates a well selected ABV, leaving it in the hands of the whisky-makers to pick the perfect proof?

Here at Whisky & Alement, especially in the past few years, we have noted a surge in the cask strength whisky world. But why is this? Is it, in part, due to the fact that with a cask strength bottling, comes the guarantee that the whisky in your glass has not been stripped by means of chill-filtration? Or is it more simply the appeal of an undisturbed, raw and natural product?

Regardless of “why”, we’re here to understand the “how”.

How are the chemical compounds that make up the flavour profile in your glass, ultimately affected by the addition of water? And, what lengths do our whisky-makers go to, to maintain the integrity of these flavours? In an interview with Heather Tillott, Production Manager of Tasmania’s multi-award winning distillery, Sullivans Cove, a bright light was shed on the topic:

Heather Tillott and the crew at Sullivans Cove in 2018

Heather Tillott’s 101:

“Ethyl alcohol (ethanol) is the main type of alcohol in spirits, and what we mean when we talk about the alcohol content of a drink. Ethyl alcohol mixes with water, without too much of a tantrum.”

“Fatty acid esters are a type of compound that smell and taste great, and make up a huge portion of what we smell and taste in whisky. An ester = a fatty acid + an alcohol getting jiggy together. These guys don’t like water.

In an alcoholic solution, the little ethanols help out the fatty acid ester molecules that freak out in the water, by forming a cute molecular scrum around them, which veils a lot of their aroma and taste.”

According to Tillott, when water is added, two things happen:

“The little ethanols loosen their grip, and so, the nice smelling/tasty esters get loose in the liquid. When these compounds break through the surface of the liquid, we can smell them! The compounds that really hate water, they want to hide in the ethanol scrums”

“So, when water is added, some esters are released and others hide. Given the amazing aroma and flavour compound differences between whiskies, and the huge range of ABV one can play with, the different levels and proportions of the flavours is endless.”

Now, let’s geek-out for a minute. When we put our nose in the glass, which are the esters that make up the first impression of our dram in hand?

“Generally, we smell the shorter chain fatty acid esters first. They’re more volatile – the ones that reach out of the glass to pull us in. Think the solventy, gutsy, full on fruit notes – ethyl acetate is the classic (sweet and fruity; used in a wide array of things from glues and nail polishes, to artificial fruit essences). Ethyl formate is another classic – smells like rum, tastes like raspberries, and interestingly, the molecule has been found in dust clouds from a certain area of the Milky Way!”

“When you pour a dram, give the liquid a swirl, and notice the change in aroma and taste after a few minutes. Initially those above full-on aromas are everywhere, and then they subside (they evaporate very readily). The longer chain esters are more noticeable after a few minutes – think ethyl palmitate (beeswax), ethyl caproate (apple, aniseed), ethyl caprate (sweet fruit, waxy), ethyl laurate (sweet apples) etc. This is why after a few minutes post-dram-pour, there seems to be more balance on the palate.”

But what happens when producers want to bottle whisky at a lower ABV, without chill filtering? And, how do they avoid ‘shocking’ the spirit? This happens via a process called “Flocking”.

When a cask is decanted into a drum, ready to be diluted to the desired bottling strength, various particles in the whisky become visible. These particles create a haze throughout the spirit that will eventually, whether it be in weeks or months, drop down to the bottom and become a sediment known as “flocculant”. Only then, when the whisky above the flock-line is clear, is it off to the bottling room. The only filtration that takes place at Sullivans Cove is after the careful extraction of clear liquid off of the top, this is when the thick, flocky goop, is put through paper filters, “like coffee filters on steroids“.

“Each of the ‘flocking’ compounds have different water and alcohol solubility factors. When you add water to reduce the spirit to the desired ABV, you change the water to alcohol ratio, which means that all of these compounds have quite a job to figure themselves out! They have ‘Who Am I’ moments as the ratio changes through reduction: am I liquid, or am I solid?”

“Some of them, who are more insoluble in water, will start the change back into solid state as soon as water goes in, and you begin to see them. The liquid becomes a bit hazy, then hazier, and then the little flocky bits become visible as the precipitates clump together.”

“The more water you add, the more this happens, as other less water soluble compounds turn to solid state as the proportionate amount of water in the liquid increases. These clumps often hang in suspension throughout the liquid for many weeks (up to a few months!) before the slow drop down to the bottom of the liquid. In this time it’s important to just let the liquid sit and do its thing. Put her back to sleep.”

“Flock has a taste, a smell, and a beautiful texture. The compounds that comprise flock have come about because of the way particular people have taken a few ingredients from a particular place to present something that represents their interpretation of that place. They are part of terroir, and they enhance our complete sensory experience of a spirit. We want to keep these lovely morsels in the picture. Love em’ big time.”

Moving forward, Sullivans Cove are going to be retaining more flocculant in their bottlings, due to their belief that the whisky smells, tastes and feels better when they leave all of the “natural flavour goodies” in there. “We dilute the whisky as normal – low n’ slow – and then leave it alone. No paper filters, just raw whisky. We’re all really excited about this – rich, textural whisky really floats our boats!”

Over at Sullivans Cove, water is added in 4-5 increments to ensure the precise ABV is achieved, and no compounds are shocked into a “perpetual haze” – a state where their precipitates don’t want to drop down at settle at the bottom.

“If reduction happens too quick, or the liquid gets splashed about roughly, or the temperature of the water being added is not the same as the temperature of the spirit, it all just freaks out and gets stuck in a haze that won’t clump together and drop down. This doesn’t look great, and poses a conundrum for those who don’t employ any sort of chill filtration. So, we avoid it at all costs by being slow and gentle with our reducing methods. Low n’ slow is the way we roll at Sully’s. It really is like nursing the liquid – we joke about doing ‘ward rounds’ amongst the diluting/flocking/settling spirits. One must be patient and gentle.”

Regardless of whether your favourite whisky was brought down 40% ABV, or bottled at cask strength, we thank those delicate chemical compounds and the masterful blenders and distillers, our custodians of flavour, that understand them so well.


The Whisky & Alement Team