Before being able to understand which of the brewing equipment is the most suitable for your expectations and production needs, it’s important to know which are the main phases that make up the production process of craft beers.
Let’s see a brief description of these phases and which components of the plant are involved in each one.
The production begins with the milling of the malt. It’s a delicate and fundamental operation that requires first of all a cereal with the right degree of friability. The grinding is carried out with mills with two or more rollers that regulate their fineness. The aim is to safeguard the integrity of the glumes, the husks adhering to the caryopsis, and to crush the white and starchy part of the grain.
This operation naturally affects the yield and quality of the final product. The fineness of the grinding has effects on the final yield too.
The degree of fineness is also imposed by the characteristics of the filtration plate. In the brewing equipment where the filtration plates have overflow lights that are too wide, the grinding will inevitably be coarser. As a result, the yield will be low.
The mixing and saccharification process is carried out in the cooking room in special tuns. Water is added to the crushed malt, according to precise proportional ratios.
The tuns of the brewhouses have a heating system, an agitator with a speed regulator and a thermal probe. The brewer, by modulating the temperatures and their residence time, activates the different enzymes of the malt so that they disgust the starch and turn it into sugars. The biochemical reaction produces sugars of varying complexity, which will determine the final characteristics of the product: body, alcohol content and foam consistency.
Usually the times of mashing vary from 90 minutes to two or three hours. The required temperatures range from 35 ° C to the thermal deactivation threshold of all the enzymes that is around 78 ° C. During saccharification, the pH must also be checked because the enzymes not only act at different temperatures, but also under different conditions of acidity.
It is also important to adjust the speed of the mixer: an excessive rate can generate vortexes, which cause the absorption of oxygen, the consequent oxidation of the mixture of water and malt and the formation of betaglucan gel. These reactions make the subsequent filtration of the must more difficult and worsen the stability and quality of the finished beer.
This operation also requires special tuns and consists in separating the must – that is the liquid fraction of the saccharified compound – from the solid residue.
The filtered liquid is collected in the boiler, which is often the same tun of mashing.
Filtration usually takes between two and three hours.
If the speed of the process is the right one, the main objective is still a particularly clear must. A relevant parameter to estimate its quality is the degree of acidity (pH) that must be between 5.2 and 5.4.
During the filtration, the washing of the threshing (sparging) is perform too, which allows to extract further quantities of sugars.
The filtered must is placed in a special boiler integrated in the brewhouse, for a lively boiling that carried out at environmental pressure, lasts between sixty and ninety minutes. During the process, the hops are added in the quantities provided for by the various recipes which, by the effect of the heat, trigger their bitter action. The heating causes the coagulation of the polyphenols with the must proteins and the solubilization of the bitter components (isomerization of the alpha-acids). It has a sterilizing effect too and, with the evaporation of water and the consequent concentration of the must, increases the sugar content. It also induces the formation of aromatic compounds between sugar and proteins, such as melanoidins (coloring and aromatic substances), while contains the impact of dimethyl sulfide (DMS), whose smell of cooked corn is easily perceptible.
From the hot must (wort) the precipitates are eliminated – the tanno-protein clots (trubs) generated during cooking – through a whirlpool effect (whirlpool).
The must then arrives tangentially in the Whirlpool tun. The circular movement pushes the liquid part towards the walls and the solid part towards the center. The effectiveness of the vortex, induced by a pump that connects the brewhouse to a piping system, depends on the input speed of the must, which must not exceed 3.5 meters per second.
At the end of the decantation pause, which takes no less than twenty minutes, and before starting fermentation, the must has to be cooled. It’s therefore introduced into a heat exchanger which lowers its temperature. Cooling should be rapid, because the permanence in the whirlpool favors the synthesis of dimethyl sulfide precursors.
The cooled must is then treated with sterile air or pure oxygen to prepare it for the yeasts. In the initial phase, yeast metabolism requires at least 9 milligrams of oxygen per liter of must.
The yeasts transform the must to make it take the chemical-physical and organoleptic profile of the beer.
For the fermentation process each brewer can adopt different techniques, which depend on the choice of low or high fermentation yeasts, the temperatures and the structural characteristics of the tanks of the brewing equipment. Carbon dioxide saturation is fundamental because it determines the final carbonation. You can get it:
- with residual extract
- with CO2 injection
- through kräusening
- through refermentation
After fermentation, the beer is pumped from the craft brewery to the tanks to get the characteristics necessary for commerce and consumption.
The maturation, which occurs at low temperatures – even below zero, allows the drink to obtain clarity and to balance, in a fairly stable form, the sweetness of the malt, the bitterness of the hops, the alcohol content and the carbonation.
Every type of beer matures at different times and for drinks, particularly complex, refermented and very alcoholic, can last for a few months.
Usually the maturity phase is between 5 and 10 weeks and the longest period is required by light beer with low fermentation.
FILTRATION AND SELLING
Before passing on to packaging, the filtration of the product is now accepted at the artisan level. It’s carried out on coarse layers of fossil, cellulose or similar flours. In this way a more limpid product is obtained, with a finer and more elegant taste.
Beer can be produced and served directly to customers in the so-called Brew Pubs, which often leave “craft” facilities for craft beer and tanks.
The beer in the barrel or bottle instead requires times and filling machinery. The packaging procedures are particularly delicate because they involve high risks of microbiological infections and chemical-physical alterations. It is therefore essential to observe the necessary hygienic precautions, even when the drinks are not at risk of oxidation as in the case of refermented products.