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The Distilling
The Pot Stills of Glenfiddich The wash is filled in the first pot still, which is called wash still and is made completely out of copper as all stills in Scotland. The heating takes place from the inside. Hot steam is lead through special formed pipes in the inside of the pot still. At a temperature of 78° C the alcohol (ethanol) starts to boil before the water does. The alcohol vapour rises inside the narrowing tube until it goes over the swan like neck at the top of the still. The vapour reaches the condensers in which it is cooled to liquid again. The water keeps mostly back inside the pot still. All single malt distilleries work with at least two separate pot stills which are fed in sequence. The first pot still distils the wash to a clear and colourless liquid with an alcohol content of 20% to 25%. This liquid is called low wines. The low wines are then pumped to the second pot still, which is called low wines still or simply spirit still. The spirit still produces a spirit with 65 to 70% alcohol. The Scottish Lowlands were famous for their triple distillation process which ended up with 75% or more. Today only Auchentoshan is left over in the Lowlands producing a single malt whisky with three pot stills. Important! When distilling you have to look after the taste carrying substances in the spirit. Pure alcohol has nearly no peculiar taste. A single malt whisky tastes only like whisky, if you keep heavier oils and fats as well as lighter esters in it. The higher you distil, the more you loose your individual taste. The special shape of the pot stills is responsible for the individual taste of the whisky. A high and slim outline leads to a smooth and weak product (e.g. Glenmorangie); whereas a short and squat shape leads to an intense taste (e.g. Lagavulin). Important for the taste is the intensity of the heating. Are you heating very much, you power a lot of accompanying substances and fusel oils over in the condenser. The resulting whisky will not be so smooth as a slow heated one. A typical slow heating run takes several (4 to 8) hours. The wash stills are normally built for 20.000 to 30.000 litres, whereas the spirit stills only contains 10.000 to 20.000 litres of the higher concentrated low wines. You have to replace the pot stills after 15 to 25 years of constant use. The thickness of the copper has then reduced to 4 to 5 millimetres. The stillman looks very carefully for any changes in the shape of the still, because any major change will also result in a change of taste. There are tales told, that stillmen add dents and bumps to the new stills to reflect the exact shape of the old one.
Spirti & Sample Safe of the Fettercairn Distillery The complete vessels and pipes are sealed by the government from the outlet of the first still on. The reason for this is the thirst of the Scotsmen, who would divert the one and the other dram of the beautiful product into their own throats without paying taxes for it. For having a look at the product and for measuring the quality of the product, all pipes are run through a small compartment with windows called spirit & sample safe. The stillman judges the quality of the whisky and diverts the stream of liquid to the different receivers and stills. This all happens through visual inspection and measuring equipment only. A stillman is not able to taste his product! In the sample compartment of the safe he measures the temperature and the density of the spirit. From this two data he is able to look up the alcoholic strength of the product in a chart. The most important work of the stillman is the switching over to the receiver for the middle cut. This counts for an excellent batch or only a good one. It takes approximately 30 minutes until the fore shot has gone through. Afterwards he collects the spirit in the middle cut for three hours which will become whisky after all. The following liquid contains fusel oils as well as higher concentrations of propanol and isopropanol. The fore shots may contain the early boiling and poisonous methyl alcohol which causes blindness after higher doses. The modern yeast strains are cultivated in a way, that they do no longer produce any methyl alcohol at all. The separation of the fore shot is therefore only a way of influencing the character today. The residue in the stills contains the fusel oils, which are responsible for the headaches. Due to the fact, that the distillation is stopped quite early, when producing malt whisky, nearly nobody tends to headaches after consuming several drams of single malt whisky. |
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