Procedure of beer brewing from malt extract
1. Raw materials
Malt extract - the quantity depends on the required alcoholic strength of the beer
Granulated hops - the quantity depends on the content of α-bitter acids
Brewery yeast - 0.5 litres per hectolitre of hopped wort
2. Descriotion of malt extract
Malt extract is made from unhopped wort, which is crushed malt carefully boiled in drinking water. The unhopped wort is finally thickened in technologically unique evaporators where water boils and evaporates already at around 45 °C, to prevent damage to the main component of the extract – malt sugar or maltose – by caramelization.
Food malt extracts are made and supplied in the liquid (thickened) condition of honey consistency or dried in the form of powder. Liquid malt extracts are thick liquids of honey consistency, sweet malt taste and absolutely typical malt smell without foreign odours. They contain about 76 % saccharides, of which about 56 % are maltose and 9 % are glucose, and a further 6.2 % of protein and 1.2 % of mineral substances.
Malt extracts are natural products not containing any preservatives or stabilisers.
3. Production of hopped wort
The malt extract is dissolved in the required volume of water with a temperature of about 30 °C. It is then brought to the boil and stirred constantly. In the course of hop boiling treated hops are added in three doses, at the beginning of the boiling stage, after 30 minutes and 15 minutes before the end. The hops are used in the form of hop granules. The ratio of these components is specified by the brewer. In the course of the hop boiling the boil must be intense - to achieve the required evaporation. The hop boiling stage is complete when the minimum required concentration of hopped wort is achieved. The concentration is measured by saccharometer 10 minutes before the end of the boiling stage. If the hopped wort concentration corresponds to requirements, the boiling stage is finished, the amount is measured in the settled pan with a bar and a hopped wort sample is taken for concentration measurement by the saccharometer. Directly before the hopped wort sample is taken, the hopped wort refraction is identified in a test glass with the use of coarse flakes suspended in perfectly pure wort. This ends the boiling process and the hopped wort may be transferred to the whirl tank, if included in the brewhouse line, or pumped by a wort pump via a tangential nozzle back to the hopped wort pan.
4. Hopped wort cooling
Hopped wort is pumped by a wort pump to a whirl tank where it is stirred with a tangential nozzle to whirl. The hopped wort is then left to mature for 20 to 40 minutes. Then the hopped wort is pumped from the whirl tank via a flat cooler to the fermentation tank. In the wort cooler the hopped wort is cooled to the fermentation temperature. The cooling takes about one house and yields about 1.2 times the amount of hot water. The important aspect is achievement of the fermentation temperature; the cooling time, quantity and temperature of the yielded hot water are not relevant. In the double-stage stainless cooler cold water from the water distribution system is used as the coolant together with ice water from an ice water generator. The hot water from the exchanger is accumulated in a hot water tank and subsequently used for malt extraction or sanitation.
5. Primary fermentation
Yeast for fermentation is added to the cooled oxygenated hopped wort pumped to the fermentation tank and the tank fill is allowed to ferment at a temperature of 7-12 °C, which is called "cold fermentation", for 6-12 days, depending on the required alcoholic strength. If more doses are to be filled in a single fermentation tank, they should be filled within a single day. The heat produced by fermentation is cooled with ice water from the ice water generator fed inside the double wall of the tank to maintain the fermentation temperature, i.e. 7-12 °C. This means in practice that the cooling is commenced on day 3 or 4, when the temperature in the fermentation tank rises to 9.5 °C. In the case of 12% beer the fermentation level established by saccharometer at the end of the primary fermentation should range between 60 and 65 %, which corresponds to 4.0-4.8 % on the saccharometer scale. Completion of the primary fermentation is manifested by a decrease in the daily loss of the extract below 0.3 % measured by the saccharometer, a darker colour of the liquid, sedimentation of the yeast and ripple of the hopped wort. This may be observed in a test glass.
6. Secondary fermentation
Young beer, corresponding to the required fermentation level, is pumped by a pump or by CO2 displacement or by oil-free pressurised air (the air pressure must not exceed 0.5 bars!) to the lager tank where secondary fermentation takes place at a temperature of 0-4 °C. From each tank 5 to 6 times the amount of the yeast added for fermentation is obtained, which is washed and may be used for further primary fermentation. The progress of secondary fermentation may be observed with the bunging apparatus. Secondary fermentation usually takes place under increased pressure. The bunging apparatus is used to increase pressure. Tank cooling with ice water is to be started immediately after bunging and the tank temperature of 2 °C should be achieved as soon as possible and then maintained. In the course of secondary fermentation the young beer acquires a balanced taste, saturation with carbon dioxide and further ripple.
7. Beer filtration and bottling
The ready beer is filtered through a diatomaceous earth filter and pumped to the bottling tank. The beer may also be bottled directly (without filtration). The bottling tanks are filled against counter-pressure to prevent the release of CO2. .
8. Yeast storage
The collected yeast is mixed in a vessel with ice water, allowed to settle and the top dead yeast removed. This is repeated every day. Thus the yeast may be stored for about one week. One yeast dose can be used for fermentation 4-5 times in succession.
9. Quality of brewed beer
The quality of the brewed beer depends on the quality of the raw materials used and, above all, on the technological discipline in the brewing and distribution. Perfect purity throughout the whole technological process is the basic assumption for top-quality production. This applies not only for the technology itself, but also for all other equipment, service areas, and raw material, half-product and finished product storage.
Instructions for operation of the individual machines and equipment are part of the accompanying technical documentation which is part of the mini brewery supply.