Hello, Roberto here, giving you the rundown of what goes on at the distillery on a mashing day.
Every whisky starts with a mash. Whether it’s single malt, single grain, bourbon or a standard blended Scotch, it all starts with this mixture of crushed cereal grains and hot water known as a mash. But how exactly does the mashing process work? What are we, as distillers, trying to achieve? Here we’ll take a look at a day in the life of a mashman/mashwoman, and fill in the gaps from all those textbooks and distillery tours.
MORNING
It’s Monday morning, it’s the west coast of Scotland so it’s probably raining. Our ton of organic malted barley has been through the mill and we’ve just warmed our mash tun with hot water (much like warming a teapot before making a brew). We’re ready to go.
Our first task is to ‘mash-in’. This is where we combine our ton of crushed malt (now called grist) with 4000 litres of hot water. The grist is conveyed from its silo while our hot water races to meet it at the mashing machine – a device which stirs the water and grist together before it falls down the chute into the mash tun. It’s kind of porridgy at this stage.

Temperature is key here. We’re aiming for a ‘strike temperature’, where the grist meets the water, of 64°C. This is the ideal temperature to convert the maximum amount of starch to fermentable sugars. Too hot, we’ll end up with lots of longer chain sugar molecules which aren’t readily fermentable. Too cold, we’ll get a poor extraction of sugar, and, potentially, a stuck mash which will cause delays for the rest of the day, and that’s the last thing we need! We adjust the temperature throughout by adding more or less cold water to the mixture, and after about 10 minutes the mash tun is full of sweet malty mash. The smell is amazing. We’ll give it a stir or two with the mash tun’s rakes and leave it to sit for about an hour. Time for a coffee.
While we’re getting our caffeine fix, enzymes within the malt are getting busy chopping up long chains of carbohydrates called starches (which would nourish the growing barley plant) into smaller sugar molecules. These simple sugars will give us our alcohol.
Once the mash has rested, we pump the surprisingly sweet, barley-infused water (now called ‘wort’) out of the bottom of the mash tun and pour it back in over the top of grains. This settles the bed of grain nice and evenly, and any bits of husk or flour which slip through the sieve-like base of the mash tun are filtered through the grain, meaning the wort we are extracting becomes clearer as the recirculation proceeds.

At Nc’nean we’re looking for a very clear wort. It allows bright, fruity flavours to develop further on in our process. Once clear, we start pumping the wort to the stainless-steel fermentation vessel called a ‘washback’. It passes through a heat-exchange on the way to cool it down, or else the heat would kill the yeast we’re about to add. Our first distiller’s yeast works fast and has a high yield, meaning it converts available sugars to alcohol with high efficiency. Our second yeast enhances the fruity aroma and complexity of our fermented liquid (‘wash’), giving notes of fresh apple and banana bread which carry through to our spirit, and really help make Nc’nean what it is.
Our annual yeast trials explore the effect of different yeasts on our new-make spirit, but that’s a whole other article!
The first wort being pumped from the mash tun is the sweetest we’ll get, but there’s plenty more sugar hiding in the mash that we’re going to rinse out by showering the grain with more hot water. This is called ‘sparging’. We sparge 2000 litres at 78°C and we try to match the rate at which the wort is being pumped out.
LUNCHTIME
After about three hours, our washback is full. Roughly 5000 litres of wort collected. Now we can see how much sugar we have extracted from the malt, a measure of the success or otherwise of today’s mash. Fingers crossed!
We take a sample from the washback and drop in a hydrometer (technically a saccharometer), which measures the density of the wort relative to water. Let’s say plain water measures 1000 on the hydrometer’s scale (meaning 1000 grams per litre).

Our wort will be denser because of the all the sugars dissolved within, and in general, the denser the better. More sugar means more alcohol. We’re hoping for a reading of 1058-1060, and we call it this measurement the ‘original gravity’.
(We’ll carry out the same measurement after fermentation to see by how much the sugar content has reduced (‘final gravity’).
From there we calculate how much alcohol our yeast has produced, usually 7.5%-8% ABV.)

AFTERNOON
We’re now on the home stretch.
We pump any remaining liquid in the mash tun out to one of our hot water tanks while rinsing the grain further, flushing out as much sugar as possible.
This sugary water, now called sparge, will be used for mashing-in and sparging tomorrow.
All the spent grain (‘draff’), stripped of its starchy goodness but still packed with proteins, gets dropped through a chute in the bottom of the mash tun and collected for feeding the local cows - they can’t get enough of it! Some of it has also made its way into experimental flapjacks and dog biscuits, though results were mixed.
After a bit of cleaning and tidying up, the day is done. The wort will ferment in the washback for the next 2-4 days and become wash (basically a strong, un-hopped beer), which will be pumped to the still for distillation.

Another wonderful “Day in the Life” from Roberto, very informative and down to earth. I love learning about the process of making whisky and know a fair bit about it, but I always learn something new from his stories. Keep them coming.
A delicious dram by the way, even though it’s exceedingly difficult to get where I am here in Canada. A visit is still on my bucket list.
Slàinte