Malt
Whisky Production Plants:____________________________________________
Manufacturing
of malt whisky is by blending of malt spirits. The process
of manufacturing malt spirits involves:
1] Malting :
Fresh barley crop is received and stored in barley godown.
Before taking in process it is graded and screened and taken
to steeping vessels where it is soaked in water. After soaking
it is transferred to Germination box where moisture is retained.
Warm air by burning Peat is circulated to start germination.
Enzymes present in the grain get activated. Just when the
grain starts sprouting, process is stopped by taking the
germinated grain to kiln where hot air is used to dry it.
Now this dried grain is called malt. It is again screened
and stored as malt.
2] Brewing :
Dried malt is ground and transferred to mash tun, a vessel
with false bottom. Hot water is added then by keeping the mass
under thorough mixing. Sugar is extracted from grain and liquid
is taken to lauter tun. Solid residue is washed using hot water
to remove all sugar and grain is removed from system as spent
grain.
Liquid from mash tun is filtered and cooled. Cooled liquid
is called Malt Brew. This is rich in sugar, minerals and enzymes,
which is later taken to fermentation.
3] Fermentation :
Malt brew is taken to fermentation and yeast
propagated bakers yeast is added to it. Temperature in the
fermenter is controlled at 30° – 32° C and yeast converts
sugar into alcohol. Malt brew after fermentation is called
wash or fermented wash / beer.
4] Distillation :
Wash is taken to pot still where steam in
jacketed or coil is used for indirect heating alternatively
a re-boiler is used. Alcohol evaporates faster than water.
Alcohol water vapour are condensed in the condenser and condensate
is collected in alcohol receiver. Alcohol strength of the condensate
is checked regularly and distillation is stopped when condensate
alcohol strength is approaching zero. Spent wash is drained
and pot still is charged again.
2nd
Distillation –
Condensate from 1st distillation is taken to another pot still
and controlled distillation is carried out. In this distillation
: -
1st product is rich in low boiling and is called heads.
2nd middle fraction is final product.
3rd or last fraction is tails.
Heads and tails are mixed or collected in separate receiver.
These are partially recycled in pot still by mixing with condensate
of 1st distillation in next batch.
Middle fraction or product is collected separately and taken
to wooden barrels or casks for maturation.
Matured spirit with specified age is mixed with G. N. S. [grain
neutral spirit]. This is called blending. D. M. water is added
to adjust strength to desired concentration [reduction] and
blended product is taken to bottling section when it is bottled
and packed.
