Brian's Malt Musings: Barley to Bottle

Wednesday 22 April 2020

Barley to Bottle - how is whisky made?

I'm sure we all know the basic process - spray some barley with hot water, cook it, add yeast, boil it 2 or 3 times? We've all done the tours, listened to the distiller tell us how it's done then had a few drams and forgotten the exact numbers - was it 50 hours fermentation or 60 hours, was it 2kgs of yeast or 20kgs, was the cut taken at 79% to 60% or 75% to 65%?

Well worry no longer, I've kept myself sober (relatively), took notes and have all the geeky detail for you here! Most photos are my own but some come from the #BlindTasting team John, Alistair, Max or Andy. You can see more of John's work here!

The process I'll be looking at is that followed by Iain McAlister and his great team at Glen Scotia Distillery in Campbeltown and I'm sure it will be pretty much the same at any other distillery.

Photo: David Watson (Glen Scotia)

Glen Scotia is the oldest surviving distillery in Campbeltown having been founded in 1832.

It's one of the smaller distilleries in Scotland with all the equipment squeezed into a small space:

Barley

Concerto malted barley is delivered once a week by a truck from Boortmalt's Glenesk Maltings.

Photo: Glen Scotia

Every Thursday 28 tonnes is normally emptied into a hole in the pavement in front of the distillery, it travels down on to a conveyor belt system along to a conveyor lift into the top of one of two huge 50 tonne Malt Bins.

The old building with pagoda (the correct term is cupola) topped roof is sadly no longer used for malting barley.

The Malt Bins fill the space where the malt loft would have been to germinate and dry the barley.

Malt bins reach up to the ceiling

Glen Scotia uses peated barley for one months production each year, usually in the Autumn, with a range of three styles: Lightly peated - up to 20ppm; Medium peated 20-30ppm and Heavily peated 30 up to a current high of 54.5ppm.

It's a long way down from the top...

Photo: Archie Mac Brayne

Milling

Ten times a week Glen Scotia start a mash, but before the barley can be used it has to be milled, it's transported from the Malt Bins via conveyor to the top of the building. From there is travels down through a 1948 de-stoner and malt-weigher into the top of a mill.

De-stoner. Photo: Archie Mac Brayne

Glen Scotia use a Robert Boby Mill dating from 1954.

The barley is ground into grist, a mixture of different sized pieces of grain in the exact ratio 70% grits, 20% husks and 10% flour. You can see the mill is currently set at 3.5 but this can be adjusted depending on the barley.

A batch of 40kgs is stored and then tipped, the mashman monitors the mill until it has counted 70 tips, he'll then have 2.8 tonnes of grist ready for mashing.

Mashing

The grist is fed via a Steeles masher into the huge 100+ year old covered cast iron rack and pinion Mash Tun.

Sparge Brewing Tank No.2 & Hot Water Brewing Tank #1 behind of the distillery buildings

The 2.8 tonnes of grist is mixed with 10,000 litres of what is called first water, usually sparge water from the previous mash (originally from nearby Crosshill Loch), at a temperature of 66°C with the steer rotating and mixing the mash twice. It's left to soak for 30 minutes then balanced with the Underback for a further 30 minutes.

The mixture is now called mash, a second water of 7,000 litres of water is added at 76°C - the mixture is already soaked and will absorb little water at this point, the steer is used once.

Photo: Glen Scotia

After around 4.5 hours the worts are drained out of the Mash Tun via the Underback over two waters, through a head exchanger to reduce the temperature to 22°C and pumped to the wash backs. A third water at 85 C is added and pumped as sparge to a holding tank and finally a fourth water at the same temperature is added giving around 17,500 litres of sparge for the following mash. The whole mashing process will take around 8.5 hours

The Mash Tun is then 'washed' with yet more water, the fifth, to remove the spent barley which is sold as draff - an animal feed for local farmers.

Photo: David Watson (Glen Scotia)

Local farmers also take away the distillery's waste effluent for use on their fields.

Photo: David Watson (Glen Scotia)

Fermentation

The 14,500 litres of wort is pumped into one of nine stainless steel Washbacks - over 7000 litres per water. The Washbacks were installed in 2012, there are six inside the building and three outside, each holds up to 25,000 litres. They are nearly 5 meters tall and 3 meters in diameter.

The Tun Room with 6 shiny stainless steel Washbacks.

1,000 litres of wort is filled into a washback then three bags of pressed yeast are added: 2 of distillers M Strain yeast and 1 of MX (faster working distillers yeast); each bag of yeast weighs 25Kgs.

Mashman Bobby adds yeast to a washback

More wort is added filling the Washback up to around 14,500 litres, it's then left for the yeast to do its work producing a 'beer' or wash of around 8% ABV.

The Washbacks are huge!

The three outside Washbacks have a slower fermentation rate due to the lower temperatures, this gives a slightly different flavour profile - with stronger fruit notes in the raw spirit

The wort should enter the washbacks at 22°C, this is tested using a thermometer on a very long rope!

Tools of the trade!

The Milling - Mashing cycle is repeated until all 9 Washback’s are filled, 10 mashes in total per week (Monday 6 a.m. to Saturday 5 p.m.). The last one is then left for at least 70 hours, the first one being over 140 hours. This gives an average fermentation time for the batch of around 128.8 hours.

As we know the yeast usually dies after around 55 hours so the secondary fermentation produces a wonderful flavour profile – Aldehydes, acids, esters etc.

Distillation

Distillation is by classic double Pot Still, the beautiful copper vessels were made by R.G. Abercrombie & Co Ltd of Alloa in 1960 although some parts have been replaced (see below the Spirit Still's bowl was replaced in 2020) The short stills produce an oily fruity new make spirit with a salty note.

Beautiful Still Room

Glen Scotia recently replaced the bowl of their Spirit Still, an exercise which involved removing part of the roof!

Photos: Glen Scotia

The wash is pumped through the two Wash Chargers then on to the Wash Still.

The Wash Still has a capacity of 11,800 litres

Batches of 7,250 litres of wash, a charge, are heated for around 4.5 hours, (9 hours per washback) boiling off the alcohol.

Video: Iain McAlister

The vapour travels up the still and hits the lyne arm, some of it condenses and falls back into the still, the rest of it continues down the lyne arm, travels through the wall and condenses in the shell and tube condensers outside in a little 'courtyard' next to the old kiln building.

At this stage the spirit is around 20% ABV and is called Low Wines.

It's collected in the Low Wines and Feints Charger before being pumped into the Low Wines and Feints Still ready for it's second distillation.

Two batches from the Wash still makes a 8,200 litre charge of Low Wines for the Spirit Still where it is distilled for up to 11 hours.

Again the alcohol travels up the still along the lyne arm and condenses in the Low Wines and Feints Condenser.

This time though the liquid travels through the Spirit Safe where it can be checked.

For the first 15 minutes or so the Foreshots, starting at around 74% ABV, are piped back into the low wines and feints receiver for re-distillation.

Once the Still Man is happy the Middle Cut at around 71% ABV, the New Make Spirit, is piped to the Intermediate Spirit Receiver, this continues all the way down until the spirits reaches 63% ABV.

The spirit is at around 69% ABV at this point and is collected in Spirit and Water Receiving Vessel (SWRV) this holds all of the new make spirit that is produced each week. Once a week, usually on a Thursday, the tank is dipped to see how much there is.

A sample is taken to measure ABV, it's normally around 69.5%, calculations are made including the temperature, strength and temperature correction factor to work out how much water needs to added to take it down to 63.5% ABV - Glen Scotia's standard cask filling strength.

Photo: Archie Mac Brayne (Glen Scotia)

Casks arrive from the Cooperage at Loch Lomond.

Photo: Archie Mac Brayne (Glen Scotia)

They normally stand in the yard for a little while before being filled.

Water is added and another sample it taken to confirm ABV before the first and second fill, medium charred, ex-bourbon casks are filled. Glen Scotia fill around 90 casks a week.

Photo: Archie Mac Brayne (Glen Scotia)

Glen Scotia is working at close to full capacity with around half a million litres of whisky being produced each year, this equates to 'normally' filling around 100 casks a week. The casks are then moved to one of the warehouses to mature.

Maturation

Glen Scotia mainly use ex-bourbon oak casks but come sherry, wine casks are also used. The casks are then laid down in either the Dunnage warehouse, racked warehouse or one of the palletised warehouses to be matured by the magic of the wood and the unique Campbeltown weather. around 12,000 casks are matured on-site.

Bottling

Once the Distillery Manager is happy that the casks have matured to the perfect point, the casks to be bottled are selected, they are sent to the bottling plant. For Glen Scotia this is at their Glen Catrine Bonded Warehouse in Catrine.