Ale -wort is the basic intermediate product for producing beer. It represents a polydisperse system with the presence of sweeteners, albumens and hop substances.
The most important technological process in producing wort is the conversion of insoluble components of hop and its substitutes (barley, wheat, rice, corn and other grains) into a soluble essence, as the result of enzymatic reactions.
Ale-wort preparation consists of five basic stages:
- grain preparation (cleaning, grading, grinding);
- conversion of extractive grain products (starch, protein etc.) into wort, as a result of mashing;
mash lautering (wort separation);
- boiling ale-wort and hops (hopping);
- wort clarification and cooling.
Grain products preparation
The basic components of malt extract include starch, other carbohydrates and proteins. Therefore, endosperm, that contains all the abovementioned substances, should be grinded as finely as possible. In the process of grinding, flour and fine grist are obtained from a brittle part of endosperm, and coarse grist (coarse grinding) is obtained from the part of a grain opposite to the corcule. As the result of grinding, the obtained malt or the mix of grinded malt and barley or other unmalted materials represents the mix of particles divided by external features into husk, coarse grist, fine grist and flour.
The dry mix of flour and fine grist, from which the extract is obtained, is easily split by enzymes in the process of mashing and then is completely converted into solution. The dry mix can not completely extract from the obtained coarse grist, while the water is hardy coming through. As the grist is slowly split by enzymes, insoluble extract converts into grains.
Lautering rate depends on the grinding quality (content of husks, coarse grist, fine grist, and flour), height of spent grain settlings and volume of grinded malt.
A technologically correct choice of malt and its substitutes along with malt grinding ensure high quality of wort and beer. High quality seasoned malt is the bulk of grain products that are present in mash.
Dust, organic and nonorganic impurities should be removed from malt and its substitutes before grinding. For this purpose, air-sieve separators with magnetic devices, flexible sieves and dusters are used.
Malt is wetted before grinding. That makes coating softer and it comes off a nucleus easily, forming optimal filter bed during mash lautering.
The goal of malt grinding is providing favorable conditions for water and ferments acting at a grind fraction, as well as for physical and chemical processes acceleration; what enables fast dissolving of substances and fermentative conversion of insoluble compounds (starch, proteins etc) into soluble ones. It means that the extract of grain products should be completely converted into wort.
Convertion of grain products extract into solution (mashing)
Mashing of grinded malt and barley with water, as well as heating and boiling of mash mass, take place in a mash mixer.
The goal of mashing of grinded malt or the mix of grinded malt and unmalted grain is solubilization of the maximum quantity of substances with the help of malt enzymes. During the mixing of grinded malt or the mix of grinded malt and unmalted grain, the particles capable of converting to solution without enzymes participation dissolve, and the substances being in a colloidal state swell. The process of mashing requires optimal temperature conditions for fermentation. That is why the mash is aged at a temperature that is most favourable for peptidases and cytolytic enzymes activity...
In the process of mashing, starch goes through three stages of change: gelatinization, dilution and saccharification. Starch dilution results in break-up of starch grains to the size of a molecule and in viscosity reduction. Viscosity reduction is achieved by vigorous blending of starch past, in other words by mechanic grinding of swollen starch grains. From then on, enzymes activity results in immediate viscosity reduction and accumulation of dextrins and maltose.
In brewing, the term "saccharification" means not just conversion of starch into sugar, but as well determination of the change of iodine solution natural colour. Saccharification results in formation of both sugars and dextrins. Iodinated starch has a typical iodine colour. Enzymatic splitting of starch is accompanied by formation of simpler carbohydrate molecules, what influences differently the iodine solution colour. The solution turns its colour from blue, purple and brown to the typical colour of a pure iodine solution. Dextrins, obtained in the result of starch hydrolysis, are simpler carbohydrates as compared to starch, but they have lower reducing capacity in comparison with maltose.
Saccharified mash at 75-78 0С is then transferred to lautering.
Mash lautering takes place in lautering tuns.
Lautering is the process of separation inhomogeneous systems with a solid internal phase, when porous partitions retain solid particles and let the liquid pass through. Coarse particles of a separated solid phase can act as a filter bed.
Lautering has two stages: first, original (first) wort lautering, and second, sparging, in which the extract kept by grains is removed.
Due to diffusion, the original wort extract converts into solution during sparging. In order to accelerate diffusion, grains are blended and continuously sparged with hot water at a temperature of 75-78 0С.
The use of hotter water will result in amylase inactivation and gelatinization of starch, which remains in malt. That will lead to obtaining trouble wort, which can add starch turbidity to beer.
The original wort and rinse waters must be pure, as the presence of small insoluble particles of mash mass imparts coarse taste to beer and can be the reason for its bed clarification.
The original wort and rinse waters are collected in a lauter receiver, until obtaining a certain weight fraction of solid substances corresponding to a guinness.
Boiling of wort and hops
Wort, transferred from lautering tuns, is boiled together with hops in a brewing cattle.
The goal of boiling of wort together with hops is stabilization of its composition and imparting hop aroma. Boiling serves to concentrate the wort to a desired specific gravity, to extract aroma and bitter substances from hops, to inactivate enzymes, to coagulate proteins and to sterilize wort.
Wort sterilization is necessary for ensuring clarity of fermentation and for obtaining a shelf-stable product, as grinded malt contains a great number of microorganisms. Sterilization is reached after fifteen-minute boiling, and acid reaction of wort contributes a lot to it. Wort sterilization and enzymes splitting enable stability of wort composition before fermentation and a long shelf life of the product. Dilution of specific compounds of hops, accompanied by the chemical interaction between sugars and protein decomposition products, enables the process of aromatization during boiling of wort with hops. Coagulation of proteins and beer clarification are of great importance for the composition, flavour, colour and clarity of beer.
Wort clarification and cooling
The goal of wort clarification and cooling is settling of the entrapped particles, reducing temperature and oxygenizing the air.
Wort clarification takes place in hydrocyclone apparatuses. The hot wort flows tangentially through inlet nozzle into a cylindrical apparatus. The entrapped wort particles gather in the centre of the bottom under the influence of hydrodynamic force and form cone precipitate. The clarified hot wort is transferred for cooling.
Cooled wort must be oxygenized to let yeast propagate at the first stage of fermentation. The injection of sterile filtered air is used for this matter.
Cooling of wort to the fermentation temperature, as well as air oxygenation, takes place in plate-coolers (heat-exchanging apparatuses).
Beer fermentation and afterfermentation
Beer fermentation and afterfermentation takes place in cylindroconical vessels. In the vessels the temperature is controlled with the help of external cooling jackets. When filling a cylindroconical vessel with clarified aerated wort, yeast is added. The vessel is filled just by 80-85% of its total volume, so there is enough space left for foam that forms in the process of active incipient fermentation.
The cylindroconical vessel is equipped with the pipe line that ensures constant bunging pressure, even carbonation and tap of gage pressure to the room without losses. Fermentation takes place at 9-14 °С until the required final degree of wort attenuation is obtained. Next, for cooling and formation of dense yeast precipitate at 0.5-1.5 0С, coolant is delivered to the cooling jacket of the cone.
In the cylindrical section, the temperature of 3-4 °С is kept for five days, afterwards the temperature is equalized with cooling jackets in the whole cylindrical section of the cylindroconical vessel. Yeast is skimmed off for the first time after ten days of fermentation. The process of fermentation and afterfermentation in cylindroconical vessels takes from 14 to 28 days. Yeast is skimmed off for the second time before clarification. Then beer is delivered to separation and filtration.
Beer turbidity can be explained by the presence of optical inhomogeneities, which initiate active light scattering. Beer contains such entrapped particles as yeast cells, protein-tanning structures, coagulated protein substances and resins. The microscopic constituents of the solid phase with their optical properties, which differ from microscopic properties of the liquid phase, determine beer turbidity.
The process of beer clarification consists in distributing disperse media into solid and liquid phases. It is achieved through separation and lautering.
Beer is filled into glass and PET bottles, cans and kegs on an automated filling line. Pasteurization is applied for beer stabilization.