The last post’ subject was about malting the barley. To prepare the malt for mashing it has to pass the milling system. At Springbank they aim to produce a grind which contains 20% husk, 70% middles and 10% flour. The mill used at Springbank was manufactured by Porteus in 1945 and despite its age still working fine. You can find mills from Porteus at nearly every distillery in Scotland. And because they never broke down or needed to be replaced, Porteus closed down after equipped every distillery in past days. Well, I really don’t like stories like this 🙁
Springbank Distillery has a conventional iron cast mash tun. Other distilleries may use a lauter or semi lauter tun.
The milled malt, which is called ‘grist’, is mixed with hot water. At Springbank all water is obtained from the Crosshill Loch which lies on the outskirts of Campbeltown about one mile from the distillery. The next picture is from Ian Rich’ FaceBook site called “Wee toon scenery“.
Ian works at Spring Distillery and is an amateur photographer.
The sole purpose of this process is to extract the maximum amount of fermentable sugars as sugar wort from the malted barley. The grist is mixed with hot water (69.5°C) in the mashing machine and enters the mash tun through a big red pipe at a temperature of 63.5°C.
After this period the grist and water in the mash tun is allowed to settle for a period of 30 minutes. This is known as stand time, after which controlled draining of the water, known as the ‘wort’ then takes place until the grist bed on the mash tun is almost dry. (from Whisky School tutorial
The whole process of mashing is a bit more complicated because the drained water is collected and used additional times for filling the mash tun. The goal is to get as much fermentable sugars out of the grist as possible.
The remaining grist after draining the water is known as ‘draft’. It is transferred into a trailer and then collected by farmers who will feed the draff to either sheep or cattle.
Now we come to the only process in whisky production where alcohol is produced. This process is called fermentation. Fermentation of worts take place in large vessels known as washbacks. The wort collected from the mashing process is filled into the washbacks. Now the 3rd ingredient for Single Malt comes into play. Yeast! The yeast, Saccharomyces cerevisiae, is manufactured in the UK specifically for the distilling industry.
At Springbank Distillery the washbacks are manufactured in wood. The type of wood is Boatskin Larch and comes from trees grown in Scotland. These vessels were manufactured by Joseph Brown of Dufftown, a specialist in the manufacture of washbacks.
In the Scottish Whisky industry you can also find washbacks made from stainless steel. There’s an ongoing debate about the influence of the material used for the washbacks, wether this plays any part in the flavour of the whisky or not.
The washbacks at Springbank have a capacity of 21,500 litres of wort. During the transfer from the mash tun the wort is cooled down to a temperature of some 16 degrees celsius. Around 30 minutes after commencing to collect worts in the wash back 75 kilos of distillers yeast is added. After the wash back is full the original specific gravity (OG) of the worts will be 1047 – 1050. The yeast converts the sugars into various alcohols, Carbon Dioxide (CO2) and heat.
Typically a Springbank fermentation is very slow and will last for up to 110 hours. A lot of distilleries have decreased their fermentation time in the last decade. Some reached less than 50 hours! Their goal is to increase productivity and we will see the results in a couple of years. I believe in the way Springbank does, that longer fermentation in the wooden washbacks will produce more complex flavours besides the alcohol.
After the fermentation the liquid is known as wash. The final specific gravity of the wash is 0.998 – 0.995. The alcohol content of the wash will be 4.5% abv.
Other distillers may produce a wash with an alcohol content of 8 – 10%. This can be done by adjusting the amount water used during mashing.
During our second night in Campbeltown we had a funny incident. At Cadenhead’s Whisky Shop we bought a bottle of Kilkerran “The Tasting Room” which we wanted to share whilst waiting for our lovely dinner at Feorlin Guest House. You can read some details about this group tasting on Bozzy’s blog here. We decided to go to the pub after the dinner but our class mate Kohei from Japan still had a little jet lag. He seems to be totally groggy and said that he needed some time to rest. He would come over to the pub later.
After dinner we all, except Kohei, walked to the pub and had some pints. Having a lot of fun talking to local people and having even more pints of Scottish ale we forgot about Kohei. When we walked back to our B&B we remembered that our class mate should have joined us and we were wondering if everything was OK with him. I decided to go upstairs to his room and ask him if everything is all right with him.
Kohei wasn’t in his room and we were a bit concerned about him. Then Bozzy said that he saw someone walking on the pavement, having his eyes concentrated on his mobile device. This crazy guy looked a little bit like Kohei but what the hell was he doing? We assumed that either this was an alien or Bozzy was drunken.
In the morning Kohei was back and during breakfast he told us his story. When he woke up he decided to join us. But first he wanted to walk through Campbeltown and check all the locations of the lost distilleries. In Cadenhead’s Whisky Shop he saw a map with all former distilleries. This map was created by a Japanese Whisky Expert that Kohei knows in person. So it was not an alien and Bozzy wasn’t too drunken. It was Kohei concentrated on his GPS and exploring the past.
The next subject will be Distilling, so stay tuned -:)