Brewing and Distilling

November 30, 2019

Beers and ales are alcoholic beverages that are popular and produced worldwide by the fermentation of grains and other sources of starch.
Grape and other fruit juices are not used for these products as they are fermented for the production of wine.
Although both the brewing and wine industries uses yeast to catalyze the fermentation itself, the amount varies for alcohol in brewed products being less than in wine and level of CO₂ is much higher.
Thus, the two products beer and wine are quite different fermented beverages having their own characteristic properties.
Regional and cultural differences can greatly influence the final brewed product in case of wines.

Wort formation

Brewing is the term that is generally used to describe the manufacture of alcoholic beverages from malted grains.
Beer, ale, porter and stout are typical malt beverages.
Germinated barley seeds are used in making malt which contains natural enzymes that digest the starch of grains and convert it to sugar.
Because brewing yeasts are unable to digest starch, “malting process” is essential for the generation of fermentable substrates.
The fermentable liquid from which beer and ale are made is prepared by a process called “mashing”.
The grain of the mash may consist of only malt or other grains like corn, rice or wheat that may be added also.

The mixture of ingredients in the mash is thus cooked and is allowed to steep in a large mash tub at warm temperatures.
During this heating period, the starches get digested by the enzymes of the malt and glucose is liberated which will later be fermented by yeast.
Proteins and amino acids are also liberated into the liquid which help in the growth of yeast as well.
After cooking, the aqueous mixture called the “wort”, is separated by filtration which is then followed by the addition of hops.
“Hops” is an herb derived from the female flowers of the hops plant.
Hops is a flavoring ingredient as well as has antimicrobial properties which help to prevent contamination in the subsequent fermentation.
The wort is then boiled for several hours in a large copper kettle by which the time required ingredients from the hops are extracted.
Also, the undesirable proteins present in the wort are coagulated and removed and the wort is sterilized in this step.
The wort is then filtered again, cooled and transferred to the fermentation vessel.

The fermentation process

There are two major types of brewery yeast strains. They are top fermenting and bottom fermenting.
The main distinction between these two strains is that top-fermenting yeasts remain uniformly distributed in the fermenting wort and are carried to the top by the CO₂ gas generated during the fermentation whereas bottom fermenting yeast settles down.

Top yeasts are used in brewing of ales and bottom yeasts are used to make lager beers.
Bottom yeasts are given the designation Saccharomyces carlsbergensis and top yeasts are known by Saccharomyces cerevisiae.
Top yeast requires higher temperature (14-23⁰C) as compared to bottom yeasts (6-12⁰C) due to which in shorter time the fermentation is completed.
It means 5-7 days are required for top fermentation whereas 8-14 days for bottom fermentation.
After bottom yeast completes lager beer fermentation, the beer is transferred into a large tank where it is stored in the cold (about -1⁰C) for several weeks.
The beer is then filtered and placed in storage tanks from which it is then packaged.
Top fermented ale is stored for only short periods at higher temperature (4-8⁰C) which adds characteristic ale flavor.

Distilled Alcoholic beverages

These are made by heating the previously fermented liquid to a temperature that volatilizes most of the alcohol.
The alcohol is then condensed and collected in a process called distilling.
A product much higher in alcohol content can be obtained by this process than by direct fermentation.
Virtually, any alcoholic liquid can be distilled and each yields a characteristic distilled beverage.
The distillation of malt brews yields whiskey, distilled wine yields brandy, distilled fermented molasses yields rum, distilled fermented grain or potatoes yields vodka, and distilled grain and juniper berries yields gin.

Image source: kwalityoffset

The distillate contains other volatile products that arise from the yeast fermentation or from the ingredients themselves beside alcohol.
Some of these other products are desirable flavor ingredients whereas some are undesirable.
The distilled product is almost always aged usually in oak barrels to eliminate the undesirable products.
This process is called “aging” which removes undesirable products and develop desirable new flavors and aromatic ingredients.
The fresh distillate is typically colorless whereas the aged product gains yellow or brown color.
The character of the final product is partly determined by the manner and length of aging, and aging times of 10 years or more are not uncommon for some distilled spirits.

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