Barley, which is the main raw material in beer, does not give, as
such,
a fermentable extract with the yeast. By brewing it in hot water we
would obtain a poor result.
It must first be left to begin to germinate. In this way enzymes are
formed that attack the grain content and
dissolve it in the water during the brewing process.
A lot of the starch, particularly, transforms into fermentable sugars,
through the enzyme action during the brewing process.
This beginning of germination is called the malting.
This prerequisite stage of production often makes up an industry in
itself, called malting industry.
During the malting process the grain is first steeped for approximately
three days, then it is spread
out in layers for a week to germinate and finally germination is halted
by desiccation in a kiln or by a kilning process.
This serves to solubilise the starchy and proteinic matter in the malt.
Three litres of water at 50°C per kilo of malt is put into a boiler equipped with a powerful agitator.
It is heated progressively in stages. Each temperature corresponds to the optimum action of an enzyme.
For example:
50-55°C is the optimum for proteolytic enzymes. Proteins ->Peptones ->Amino Acids.
62-63°C is the optimum for B amylolytic enzymes. Starch ->Maltose.
73-75°C is the optimum for 
amylolytic. Starch->Dextrins.
The brewer may act on the composition of his beer wort by his choice of stages.
As maltose is fermentable, but not dextrins, he may obtain beers that are more or less rich in alcohol.
The brewing process lasts about two hours. Then, the mash is filtered either in a perforated vat or in a filter press.
The insoluble matter makes up the slop (25% of the weight of the malt).
The wort is sent to a cooking boiler heated by steam pipes (this was formerly done in a fire pit).
After it has boiled for half an hour, 150 to 300g to the hectolitre of hops is added,
according to the desired strength and degree of bitterness.
The total boiling time is between one and a half to two hours. The wort is then clarified,
cooled and aired (to encourage the yeast to develop). It is then sent to a fermentation vat.
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Yeast is added to the wort, once it has cooled, and the fermentable sugars that dissolved
during the brewing process are transformed into alcohol and carbon dioxide.
After about a week this fermentation is finished.
There are two main categories of beer here, “bottom-fermentation yeast” beers,
which are fermented at a low temperature (5 to 10°C) with a yeast that sinks to the bottom of the beer,
and “top-fermentation yeast” beers, fermented at 15 to 25°C, with a yeast which rises to the surface of the beer after fermentation.
The former originated in central Europe and spread to the rest of the world.
The second are mainly brewed in England.
Approximately half of the top yeast beer comes from Belgium.
In France, the top yeast method is rare. The difference in taste and flavour between the two methods of production is very distinct.
The bottom yeast (Uvarum saccharomyces), having little flavour and a fairly neutral taste,
lets the flavour and taste of the hops circulate and gives fine beers. This is the yeast used in classic pilsner beers.
Top yeast (Cerevisiae saccharomyces) is an energetic yeast that reproduces greatly and only
works well at a temperature of more than 15°C. It produces beers with much more aroma and flavour,
appearing lighter and more digestible even when their specific gravity is very high.
This yeast is ideal for specialty beers. It should be noted that top yeast beers should not be drunk too cool.
In both cases, there are many strains available to the brewer. It is up to him to choose the one that best suits his particular needs.
After fermentation, the beer goes into storage for several weeks at 0°C.
The aim of this storage is to refine the taste, partially clarify the beer and to saturate it in CO2.
Top yeast beers, in general, are subjected to a short cooling period.
Next comes the conditioning: clarification by centrifugation or filtration over infusorial earth.
It is biologically stabilised through pasteurising, filtering or sterile filtering, then put into barrels or bottled.
The degree of alcohol of the beer
The French Regie degree corresponds to the second decimal place of the wort specific gravity before fermentation.
For example: a beer with 5° alcohol means the beer wort weighed 1.05.
In Germany and Central Europe, it is expressed using the Balling degree, which is the percentage of wort extract
when dried before fermentation. There is no close link between the density and the degree of alcohol.
It all depends on the raw materials and methods of production.
For traditional beer, however, the degree of alcohol is close to the Regie degree.
The beer contains approximately 200 different substances, most of which originate from the yeast metabolism.
It is the only drink that froths because it contains colloidal nitrogenous substances.
These, along with the vitamins and mineral salts, make the alcohol in the beer much less harmful than in other alcoholic drinks.
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The beer is filtered to take away the yeast particles, and then bottled.
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