Production Of Beer By Spontaneous Fermentation

The Production of Beer by humans began with spontaneous fermentation through yeasts present in the environment. This tale and the details attached to it provide us with an unwritten document about the human ingenuity that lay in the power of human observation and deduction, even when the very basic components of our knowledge and understanding were missing.
Production of Beer by Spontaneous Fermentation
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Spontaneous fermentation makes use of yeast and fermenting bacteria present in the environment, for the process of fermenting sugar of malt in to alcohol of beer.

Beer is a product of fermentation of sugar by yeasts and bacteria. These yeasts can be cultivated, and most beer in the world today is made from such cultivated yeasts. However, yeast and fermenting bacteria are also present in the environment. These yeasts were originally used in making beer, long before humans knew about them, by exposing the malt extracts open to the environment which contained these yeasts. Today, this age old process of brewing

is used commercially only in a small location in Belgium, surrounding its capital Brussels, in the valley of the river Zenne, in a small area called the 'Pajottenland.'


All beers up to the middle ages were brewed using the spontaneous fermentation process, as neither it was possible to isolate yeasts nor could it be cultivated in the way they are done now. The yeast used was usually the same used for making bread and came from environment. The ancient historical recipes and brewing methods are based on the same process. A recipe for making 'Sikaru', a beer popular among Sumerians about 6000 years back shows that it was made using 60% malt and 40% wheat which were allowed to undergo wild fermentation and then flavored with cinnamon. The recipe is not very different from other ancient beer recipes, or the recipe for brewing the Lambic beer in Belgium today.

Features of Spontaneous Fermentation

The most important feature of spontaneous fermentation is that no cultivated yeast is added in it. Instead, the wort is left open to the environment. The yeast and bacteria present in the environment inoculate this wort, and start fermenting the sugars in it. One important implication is that such a process can work only in environment that contains the desirable yeast while being free of other harmful micro-organisms that can spoil the beer.

Typically, spontaneous fermentation process uses unmalted wheat content of up to 30%, unlike other processes where unmalted cereals are not that high in content.

The process of spontaneous fermentation is far slower compared to the brewing done with addition of yeasts. Hence spontaneous fermentation may be required for a period of years before the beer is ready for consumption. This perhaps is one single reason that makes the process costly and somewhat difficult for very large volumes.

In summers the number of harmful bacteria in the environment is far more than the amount of yeast and hence summers are not the appropriate time for spontaneous fermentation brewing. Most such brewing is restricted to the winter months, while in summer the brew that is already fermented partially is only allowed to ferment further.

Due to the greater exposure of 'wort' to environment and bacteria present in it, chances of contamination by harmful bacteria are also more. To take care of this, a greater amount of hops need to be mixed in wort. As hops have a bitter taste, so to avoid the bitterness while retaining their

antiseptic effect, old hops are used in spontaneous fermenting, which give the beer a taste that is less bitter and with a different flavor.

In case of beer made from spontaneous fermenting, the process of fermentation goes on for years and actually continues even after the beer is bottled. Thus the bottled beer also undergoes a change of taste and flavor. Older beers have a different flavor, one of the reasons why such beers are sometimes compared to wine.

Process of Spontaneous Brewing

Brewing in this method begins with mashing of water, malt and 30% wheat at 45 degres celsius. Heating of malt releases starch in the mixture which is also referred to as 'batter'. Further warming of batter to 52 degrees allows protease enzymes present in the malt to break proteins and result in a milky mixture. Further increase in temperature to 65-75 degrees stimulates enzymatic conversion of starch in to sugar.

This mixture, after filtration, is called 'wort'. it is seasoned by adding old, dry hops and boiled for 4 hours and then cooled in ventilated rooms overnight. This is the point when inoculation of wort by environmental yeasts takes place. Over 85 different micro-organisms that can inoculate wort and cause spontaneous fermentation have been known in Brussels where Lambic beer is produced by this method. Different yeast or enterobacteria may act at different points of time and for different durations depending upon the acidity of the wort and other conditions. The important ones are Brettanomyces Lambicus, Brettanomyces Bruxellensis and Saccharomyces.

The inoculated wort is put in old wooden barrels made of oak or chestnut, where the fermentation can start. Old barrels are used because old wood has lost its tannin. Nowadays metallic containers are also used, but the type of container and its micro-environment has an impact on the flavor. In a few days, the fermentation starts and is marked by appearance of white foam, which, later becomes brown and cats as a natural stopper. The fermented wort is shifted to another container for a second fermentation and so on, upto two years. The spontaneous fermentation, followed by the maturation in old oak barrels gives these beers their unique taste and flavor.

Types of Beer Produced by Spontaneous Fermentation

The two main varieties in the world today are the 'Lambic' and the 'Gueuze', both produced in Belgium. The Gueuze is actually a mixture of a young lambic and an old lambic in a proportion that gives it a unique taste. Some other variations are also made by adding fruit extracts to the beer.

Since the spontaneous fermentation depends upon environment, the same beer cannot be prepared at different places. This is the main reason why Lambic and Gueuze cannot be produced easily elsewhere in the world.

Article Written By V Kumar

I am a freelance writer. I write for the passion of writing. Life has blessed me an opportunity to be a witness to many interesting aspects of life and people around the world. Indeed, these are very interesting times and we who live in this era are privileged to experience it. You can find my articles at

Last updated on 28-09-2017 428 0

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