Ingredients
The chemical processes which take
place during the manufacture of
grain spirit are broadly similar to
those which occur when malt whisky
is made. Both the raw materials and
the equipment are different,
however. The mash from which grain
whisky is made uses unmalted cereals
- usually wheat or maize, it doesn't
matter which, so distilleries can
buy at the best price - together
with a small amount of 'green'malt
(barley which has germinated but not
been kilned). Usually about 16% of
malt is added: it has to be there to
convert the starches in the other
cereals into sugar, so it can be
turned into alcohol by the yeast.
Mashing and Fermenting
The cereals are finely milled then
cooked at high temperatures in a
pressure cooker.The pressure is
provided by the direct injection of
steam, and the purpose of the
cooking is to soften the husks of
the grain and dissolve the starch
into solution.The slurry thus
created is cooled and transferred to
the mash tun, where a measured
amount of green malted barley is
waiting, and the whole lot is mashed
(i.e., converted into a sugar
solution), as for malt whisky.
Oils
in the maize
The wort, and any solids it
contains, is drained off after an
hour or so, cooled and pumped to a
fermentation vessel, where yeast
cream is added. Fermentation
continues for forty-eight hours,
during which time the sugar is
converted into alcohol (at between
6% and 7%) and carbon dioxide.The
wash for grain whisky does not
bubble quite so vigorously, because
of the oils in the maize. It is also
lower in alcohol.
