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What is a single whisky?
A
single whisky is the product of one particular
distillery.
What is meant by saccharify?
To saccharify means to convert to sugar. In whisky
distilling it refers to the process which takes
place during the malting and mash-tun stages by
which enzymes in the malt, referred to as diastase,
turn the starch in the cereals into sugar ready for
the fermenting action of the yeast.
What is diastase?
When conditions of temperature and moisture favour
germination, the embryo and associated parts of the
barley grain secrete a mixture of enzymes commonly
known as diastase. These act to modify and make
soluble the starch in the barley, thus preparing it
for conversion at a later stage to maltose.
What is wort?
Wort is the liquid drawn off the mash-tun in which
the malted and unmalted cereals have been mashed
with warm water. Wort contains all the sugars of the
malt and certain secondary constituents. After
cooling, it is passed to the fermenting vats. In
Malt distilleries the cereals are all malted; in
Grain distilleries a proportion only is malted, the
remainder being unmalted. In some cases, Grain
distilleries do not separate off wort, passing the
complete mash to the fermentation vessels.
What is wash?
The wort or mash technically becomes wash as soon as
yeast is added to start fermentation. However, the
term is usually used to refer to the liquid at the
end of the fermentation. It is the wash which forms
the raw material of the first distillation in the
Pot Still process and of the only distillation in
the Patent Still process.
What is the pot still distillation?
Malt Whisky is distilled twice - although a few
distilleries may undertake a third distillation - in
Pot Stills which resemble huge copper kettles.
The spirit is driven off from the fermented liquid
as a vapour and then condensed back to a liquid.
In the first distillation the fermented liquid, or
wash, is put into the Wash Still, which is heated
either directly by fire or by steam-heated coils.
At this stage the wash contains yeast, crude
alcohol, some unfermentable matter and the
by-products of fermentation. During the process of
boiling the wash, changes take place in its
constituents which are vital to the flavour and
character of the whisky.
As
the wash boils, vapours pass up the neck of the
still and then pass through a water-cooled condenser
or a worm, a coiled copper pipe of decreasing
diameter enclosed in a water jacket through which
cold water circulates.
This condenses the vapours and the resulting
distillate, known as low wines, is collected for
re-distilling. The liquor remaining in the Wash
Still is known as pot ale or burnt ale and is
usually treated and converted into distillers’
solubles for animal feed.
The
low wines are distilled again in the Spirit Still,
similar in appearance and construction to the Wash
Still but smaller because the bulk of liquid to be
dealt with is less. Three fractions are obtained
from the distillation in the Spirit Still. The first
is termed foreshots, the second constitutes the
potable spirit, and the third is called feints. The
foreshots and feints are returned to the process and
redistilled in the Spirit Still with the succeeding
charge of low wines. The residue in the still,
called spent lees, is run to waste.
In
the case of the Spirit Still, the design of the
still, the height of the head (or top) of the still
and the angle of the wide-diameter pipe or lyne arm,
connecting the head to the condensing unit, are all
very important and have an effect on the distillate.
The
Pot Still has changed little in general design over
the centuries.
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