Beer production

The raw materials used in the production of beer are four:

• barley (and / or other cereals),
• the water,
• hops,
• and yeast (unless natural fermentation takes place).

Barley is usually tender barley, while barley - richer in proteins - is intended for human consumption in other forms (flakes, flours, oven preparations, etc.).

In order to be used, tender barley - richer in starch than the previous one - must first be transformed into malt, through a process called talling. It starts naturally from the caryopses (therefore from the grain), which is subjected to washing and calibration (using sieves); a maceration of two or three days in water follows (until the grain reaches a humidity close to 45%). During this period, the germ of the caryopsis begins germination, emitting a radicle and a first shoot; however, the most important changes concern the substances contained in the grain, which go against an intense enzymatic transformation (mainly due to amylases and glyco and proteolytic enzymes). Amylases, in particular, begin to degrade starch, splitting it into ever smaller molecules (dextrins) up to maltose. Among these substances, dextrins are found intact in beer, while maltose is used by microbial strains in the subsequent phases of alcoholic fermentation.

After germination, the barley is dried (at 65 - 70 ° C, subsequently at 80 ° C or at higher temperatures for red and dark beers), with the aim of blocking the enzymatic activity which, perpetuating, would damage all carbohydrate and protein structures (important for subsequent processing steps). The drying also affects the rootlets, which are thus removed more easily.

In the preparation of beer, a much more important ingredient than one might think is water; in fact, it must be of low hardness (around 7-8 French degrees, because - if it is too hard - the acidity of the must decreases, reducing the fermentative action of malt enzymes) and sweetness (if too sweet it has a excessive solubilizing power on the components of hops and therefore confers to the beer a more acrid taste).

The third ingredient of beer is hops ( Humulus lupulus, family Urticaceae), of which only female inflorescences are used, rich in tannins and resinous substances with a bittering power, from which the luppolino is obtained; therefore, the amount of added hops - just a few grams per liter is enough - affects the more or less bitter taste of the beer.

The fourth ingredient is given by yeasts, such as Saccharomices carlsbergensis and Saccharomices cerevisiae, which - in addition to carrying out alcoholic fermentation - contribute to giving the beverage its typical organoleptic characteristics.

After drying, the barley, which can now be called malt, is ground and mixed with water; a mixture is thus obtained which is then subjected to heating at 55-60 ° C, by means of a process called saccharification (since the enzymes degrade conspicuous amounts of starch, forming dextrins and maltose, and hydrolysing proteins, forming small peptides and typical free amino acids of beer). This mixture of barley malt and warming water is called must, as it is the starting point on which to carry out the subsequent alcoholic fermentation.

In the following step there is the separation - by filtration - of the liquid part from the solid part; the latter, called threshing, is used in animal husbandry for feeding livestock and in fertilizing the fields, while the filtrate, still without aroma, is added to the typical flavoring substance, which is precisely the hops. This is added as a function of the flavor you want to give to the beer, after which you proceed with the boiling for a couple of hours of the filtrate. During the boiling process the aromatic components of the hops are solubilized (especially resins and tannins, which give the beer its typical slightly astringent taste); at this point, after the boiling process, the must is allowed to cool, with the formation of a bottom body to be removed then by filtration. In this way an aromatized drink is obtained, with a taste similar to that of beer, but free of bubbles and alcohol. The pleasure on the palate is therefore conferred by the subsequent fermentative passage, which gives the drink a certain alcoholic degree by adding selected microbial starters belonging to the Saccharomiceae family. The previous heating and boiling processes also have the purpose of inactivating micro-organisms that may be present in the must, which can give rise, in this phase, to secondary fermentations, thus altering the taste of the beer; thanks to these steps, therefore, the fermentation process is regulated only by the selected microbial stock.

Fermentation generally takes place in large silos, equipped with a heating jacket to keep the temperature constant; unlike those used for wine, these large cylindrical containers must be perfectly sealed (to keep the CO2 formed spontaneously dissolved during the fermentation process). The fermentation of the must, initially tumultuous, can be of two types: high (15-20 ° C for 3 or 4 days; high because in these conditions the yeast strains tend to reach the surface) or low (5-8 ° C for 10-12 days, during which the strains tend to settle on the bottom). From this moment on all beer passages must be made in adiabatic conditions, so as to maintain the same pressures in the various containers (steel barrels fitted with air release valves). In these barrels a slow fermentation continues, followed by filtration or centrifugation operations, packaging and ultimately pasteurization. This last step has the purpose of blocking the fermentation process and inactivating the enzymes of the microbial strains, which otherwise would continue to operate unwanted transformations on the product.

Beer alterations are the result of technological errors, therefore of preparatory procedures not carried out correctly:

• SOFTENING (incorrect filtration, development of undesirable microorganisms, imperfect pasteurization)
• THREAD ASPECT (development of microorganisms of the genus Pediococcus, again due to incorrect pasteurization)
• LACTIC FERMENTATION (presence of microorganisms that have escaped pasteurization)
• SAPORE ASPRO (type of hops used in the preparation of beer or use of too sweet water).