Scotch is a type of whisky that is made in Scotland and uniquely stands out from other types of whisky. There are currently two different kinds of Scotch whisky available:
- Malt Whisky
- Grain Whisky
This type of whisky is made using the Pot Still Process. The process can occur in four distinct stages:
- Fermentation then:
- During this stage the barley is screened to remove any foreign matter.
- Soak for 2 or 3 days in steeps. Steeps are special water tanks.
- Spread it out on a malting floor and allow germinating. The process of Germination can take from 8 to 12 days. Turn out the barley regularly at intervals to control temperature and germination rate. The barley secretes the enzyme diastase during germination that makes the starch soluble in preparation for conversion into sugar.
- Stop germination by drying the malted barley or green malt in the malt kiln.
- This stage involves grinding of the dried malt in a mill.
- The ground malt produces grist then mixed with hot water.
- The soluble starch is then converted into a sugary liquid known as wort. The wort is then removed from the mash tun. The remaining solids are removed for use as cattle food.
- This process begins with cooling of wort and passage into large vessels of liquid for fermentation by the addition of yeast.
- The sugar in the wort is attacked by live yeast and it is converted into crude alcohol.
- This whole stage of fermentation takes about 48 hours to produce a liquid known as wash. Wash contains;
- Alcohol of low strength.
- Some unfermented matter.
- Certain by-products of fermentation.
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Distillation of Malt Whisky is done twice in large copper Pot Stills.
- The liquid wash is heated to a boiling point for the alcohol to change to vapor.
- The vapor rises in the still and is passed into the cooling plant. In the cooling plant, it is condensed into a liquid.
- The purpose of first distillation is the separation of the alcohol from the fermented liquid and elimination of the residue from the yeast together with the unfermented liquids.
- The distillate produced is known as low wines. The low wines then pass into another still where it is distilled a second time. In this second distillation first and the last runnings are not collected. In spirit bottles. Only middle runnings are collected.
Pot Still distillation is a batch process.
Image credit: “Glenmorangie Distillery Stills” by Jack Shainsky
This whisky is made by a process known as the Patent Still process. The process is continuous in operation and differs from the Malt Whisky Pot Still process in four other ways:
- The mash in this process consists of a proportion of both malted barley together with cereals that are unmalted.
- Unmalted cereals used in this process are cooked under steam pressure for three and a half hours while the mixture of grain and water is being agitated by stirrers located inside the cooker.
- The grain starch cells burst and upon transfer of this liquid to the mash tun together with the malted barley, the diastase present converts the starch into sugar.
- Unlike Pot Still process, the wort collection is done at a lower specific gravity.
- Distillation occurs in a Patent or Coffey Still and the spirit collection are done at a much higher rate.
The maturation of both types of whisky occurs after distillation is completed. Casks of oak wood that are permeable are filled with the new spirit. They allow air to pass and evaporation to take place. The process allows removal of harsh constituents and in due course becomes Mellow Whisky. Malt Whisky takes a longer time, up to 15 years, to mature because it contains more flavory constituents compared to Grain Whisky.
Other factors that affect both Malt and Grain Whisky maturation include:
- The size of used casks.
- The temperature and humidity of the warehouse.
- The strength of storage of the spirit.
The different whiskies are blended together after maturation. The addition of soft water creates a reduction of the blend to the required strength. The color of the whiskies at this stage, before blending, depends upon the casks used in the previous stage.
This marks the final stage in the process of production of Scotch whisky before dispatch. Scotch Whiskey for exportation is packaged in glass tanks lined with stainless steel or casks of varying size. The packaging, in this case, depends on the size of the market. Bottling is then done overseas by the agents or distributors.