The dried grain kernels need to absorb moisture in the softening House so that the barley can germinate. This process takes 50 hours. Throughout this time the barley is aired and washed using pumps. Through the water separator, the barely “dives” – as the brewers like to say – into the softening vat.
Round softening vats and water separation prepare the grain during the even and slow insertion of the barley. (Picture 2/3).
In every beer, the most important ingredient is malt. Bottom fermenting beers uses barley malt, while top fermenting beers allow the use of other malts. For example, in addition to barley malt, wheat malt will be used. In Athenian Brewery S.A, special malting and brewing barley types have been germinated and cultivated. Important to the barley cultivators are full kernel, fine spelt (husks) and rich enzyme content. Most beer barley types have a lower yield than the barley that feeds animals. With their special ingredients, though, they reach a high yield during fermentation and add to beer’s noble taste.
From Barley comes “Green Malt”
Raw barley is not ready to be used in brewing. In order to “unlock” the hidden ingredients, it needs to be malted. To do this the barley, after being cleaned and sorted, is soaked for two or three days in a large vat full of water, where they swell and then begin to germinate. Germination enhancing chemicals are forbidden. The barley kernels soak up water quickly at the beginning, and then more slowly during the soak. With the proper temperatures and rich amounts of oxygen, the barley begins to germinate. Finally the barley is laid out for five days to germinate. With the right amount of air, it becomes “green malt”
In order to stop the germination, the malt is kiln-dried under high temperatures. Moisture, Temperature and the length of the drying process determine if light or dark malt (and with it the ingredients for lighter and darker beer styles) will be made and give malt its typical malt aroma.
The finished brewing malt contains only 3 or 4% moisture and is now ready to be stored. It is cleaned and separated from the germinating malt, dusted and polished and then stored in silos that are well ventilated and protected from dust development. The germination sets biological changes within the kernel into action: Enzymes are activated or newly created. These developments are only interrupted by the kiln-drying. During the mash (the mixing of the ground malt with water) the enzymes – as desired – become active again.
The malt is now ready for the brewing process. Production methods will differ from brewery to brewery, as well as according to brewery equipment and beer types. Athenian Brewery S.A uses its own production methods; however the main processes will be similar. The description below applies to the production of a typical lager beer in a brewery with a lauter tun installed.
The first stage in the brewing process is the preparation of the wort. After the malt is crushed to grist of suitable fineness, and preliminary treatment of the adjuncts takes place to facilitate extraction, the malt and adjuncts are mixed with brewing water to form a mash. Adjuncts are a supplementary sugar supply, provided either as starch (e.g. maize grits or rice) or as sugar or glucose syrup. Glucose syrup can also be added later to the wort kettle. The mash is heated, following a pre-set time-temperature program, in order to convert and dissolve substances from the malt and adjuncts in the brewing water. (The brewing water is often called ‘liquor’.)
Extraction is accomplished through a combination of simple dissolution and the influence of the enzymes formed during the malting. The substances dissolved in the water are collectively called the “extract”. The solution formed is called the “wort”
When the mashing is completed, the spent raw material, called the “spent grains”, is separated from the wort by straining. The wort is then boiled with hops or hop extracts, releasing bitter substances and oils which are dissolved in the wort. During boiling the bitter substances are isomerizes, which increases their solubility, and a precipitate consisting mainly of proteins is obtained (the “trub’). After separation of the trub, the wort is cooled to approximately lO0C. The cooled wort is transferred to the fermentation area.
In order to obtain a high yield of extracted substances as quickly and efficiently as possible, the malt must first be crushed before being mixed with hot water. Care should be taken during crushing to make sure the husks are not damaged, since they are used as filter bed for separating the spent grains when straining off the wort.
Since the extract yield generally increases in direct proportion to the degree of fineness to which the malt is milled, it would be preferable for the malt to be crushed to very fine flour. However, this would cause the filter bed to become clogged during most wort straining operations, resulting in an increase in the time required for separation. Moreover, the bed would become less permeable, leading to the hold-up of valuable extract within the spent grains. Spargin2, if used, would also be less effective in recovering extract. The fineness to which the malt is milled is therefore a balance between best extract yield and ability to filter the wort.
The purpose of mashing is to obtain a high yield of extract (of the highest possible quality) from the malt grist and adjuncts by extraction in the brewing water. Only a minor part of the extract is obtained through ordinary dissolution, while the remainder is extracted by means of the enzymatic breakdown of complex insoluble substances to simple water-soluble substances. Factors such as temperature, PH and length of time of the mashing must be carefully controlled so as to create optimum conditions. Conversion temperature is typically 650C, but mashing may begin at lower temperatures (e.g. 45OC) if the malt is relatively tinder-modified.
Some classes of proteins and starches are insoluble in water. During mashing, the proteins are broken down by an enzyme system. Proteases hvdrolyse the proteins to peptides and other less complex nitrogenous compounds, and peptidases subsequently break down the peptides to amino acids. The starch is broken down by the amylase enzyme system to glucose, maltose and dextrins.
In case of poor malt quality, enzymes from the malt can be supplemented with exogenous enzymes.
Adjuncts such as rice and maize are not pre-germinated and do not contribute enzymes. Furthermore, their starch has a higher gelatinization temperature than malt starch. The adjunct is therefore mixed with water and cooked. The adjunct mash is then mixed with the malt mash and the malt enzymes break down the adjunct starch. Sugar and glucose syrup can also be used as adjuncts. Since no enzymatic breakdown is required, these adjuncts are added to the wort kettle.
During mashing, the substances in the malt and adjuncts are broken down and dissolved in the brewing water. In addition to sugar and protein compounds of various complexities, the mash also contains insoluble material (spent grains). The wort is separated from the spent grains by straining through a porous filter bed formed by the husks. The residual extract in the filter bed is leached out with sparging water.
The temperature of the wort during straining is about 75-780C.
Following removal of the spent grains, the wort is heated to boiling in the work kettle and addition of the hops takes place.
I.All enzymes are inactivated to prevent the continued breakdown of proteins during fermentation.
3.Bittering of the wort occurs via isomerisation of hop alpha-acids.
4.Unstable colloidal protein coagulates and precipitates.
5.Unwanted flavour components evaporate from the wort.
The wort is normally boiled vigorously for about I.5 hours with a minimum boiling intensity of 5-8% evaporation per hour.
The degree of wort clarity required depends on the type of beer being produced and on brewing practices. The wort should be clear and free of particles “hot trub” ) before entering the fermenting vessel.
Particles, especially small ones, carry lipids which in high concentration have a marked influence on the formation of ester and higher alcohols, as well as the production of other flavour components from yeast during fermentation.
The equipment most commonly used for wort clarification is the whirlpool, in which the wort and trub particles are introduced in a tangential mode. Secondary forces on the particles cause them to migrate and accumulate in a cone at the centre of the bottom of the vessel.
After clarification, the wort is cooled to a temperature of typically about 10OC. Cooling normally takes place in a heat exchanger. The hot water produced is collected and used as brewing water.
After the wort has been cooled to the fermentation temperature, oxygen is added. The wort is then pumped to the fermentation tanks, where yeast is added. Oxygen is necessary to support development of the yeast to a state and amount capable of fermenting wort efficiently. Fermentation is an anaerobic process: the yeast metabolises the fermentable sugars in the wort, forming alcohol and carbon dioxide.
Heat is generated during fermentation. To maintain the desired fermentation temperature, the fermentation vessels must he cooled.
Once primary fermentation has occurred, the yeast is cropped and pumped to storage tanks. During fermentation, yeast is produced in excess. A part of this yeast is reused for a new hatch of wort, the remainder being discharged or treated as a by-product. The production yeast is typically reused several times (perhaps up to ten generations).
The yeast treatment involves the following functions:
• Yeast propagation, i.e. production of new yeast
•Storage and discharge of surplus and spent yeast
The beer is stored for a certain period following primary fermentation.
The objective of storage is to obtain:
•Settling of yeast and other precipitates
After storage, the beer is ready for filtration.
For beer with a very high yeast cell count, a centrifuge may he necessary for pre-clarification prior to filtration in order avoid blockage of the filters. Installation of a centrifuge may further reduce the consumption of kieselguhr, the filtration medium.
The cooling of beer prior to filtration is important in regard to shelf life, since a forced precipitation of haze particles takes place at this stage rather than hater in the bottles. Cooling must be controlled very carefully to ensure a constant beer temperature of approximately -10C to -l.5C.
The purpose of filtration is to obtain the specified low level of initial haze in the beer and to facilitate prolonged shelf life.
Filtration typically takes place in a kieselguhr (diatomaceous earth) filter. Perlites (volcanic residues) are sometimes used instead of kieselguhr. Diatomaceous earth performs the filtration, with the filter itself acting as support for the filter cake.
The small diatoms form a rigid but porous filter cake which sieves out particulate matter as it passes through the filter. To prevent “blinding” of the filter, and to achieve extended filter runs, kieselguhr is continuously dosed into the unfiltered beer as “body feed”, thereby constantly building up the depth of the filter cake.
To act as a “police filter” after the kieselguhr, a cartridge filter or sheet filter can he installed.
Additives such as stabilising agents, colouring and primings (sugar) can be dosed to the beer.
In order to achieve the finished product specification for CO, the beer is carbonated before being sent to the bright beer tank. Nitrogen gas may also be used in small quantities to favour foam performance.
When the filtration process is completed, the beer is ready for packaging. Prior to packaging, the beer is stored in bright beer tanks.
It is important that all process equipment and pipes are kept clean and disinfected.
Cleaning is done by means of CIP plants, where cleaning agents are circulated through the equipment or sprinkled over the surface of the tanks. Disinfection takes place through a combination of high temperature, cleaning agents and disinfectants. Caustic and/or acid are normally used as cleaning agents. The cleaning and disinfection of the brewery equipment can involve the use of substantial amounts of energy, water, cleaning agents, and disinfectants.
Several CIP units are usually required in order to cover all the process areas in the brewery.
From the bright beer tanks the beer is pumped to the packaging area, where it is bottled, canned or kegged.
During this final operation it is important that:
•The beer is prevented from coming into contact with oxygen:
•No carbon dioxide is lost, as the beer was carbonated to specifications during beer processing;
•The beer is not infected. (If it is infected, its shelf life will be reduced and the beer will have off-flavours).
In packaging lines using non-returnable bottles and cans, the bottles/cans are only flushed with water before filling. The bottle washer consumes large quantities of energy, water, and caustic. Furthermore, substantial quantities of waste water are discharged. The use of non-returnable packaging material reduces consumption of energy, water, and caustic, therefore reducing waste water generation.
If kegs are used, they are cleaned and sterilised with steam before filling.
Before being filled with beer, the returned bottles are sent to a bottle washer which removes all impurities inside and outside. Inside the bottles, impurities include residual beer mould, cigarette butts, etc, externally; impurities may include labels, aluminum foil, and dust particles.
Bottle washing is likely to consist of soaking, rinsing, sterilisation and re-rinsing.
The bottles are transported on conveyor belts from the bottle washer to the filling machine. They are filled under pressure, according to the quantity of dissolved carbon dioxide in the beer.
In addition to tilling bottles, the most important function of filling machines (which may take various forms) is to prevent oxygen coming into contact with the beer.
After filling, the bottles are conveyed to the crowner, which fits them with crown corks. The sealed bottles are then conveyed to the tunnel pasteurizer.
Beer is pasteurised to ensure a long shelf life, although there is increasing use of sterile filtration as an alternative. It is important that all micro-organisms capable of growing in the beer are destroyed. Pasteurisation guarantees practically unlimited biological stability.
Two different methods are used for the pasteurisation of the beer:
(a) Tunnel pasteurisation, during which the beer is pasteurised in bottles (or cans), i.e. both beer and bottle are pasteurised as a closed unit;
(b) Flash pasteurisation, employing a heat exchanger in which the beer is pasteurised before it is put into bottles (or kegs).
Following pasteurisation, the bottles are conveyed to the labeler. There labels and, in some cases, foil are applied.
The bottles are now ready for packing in crates, cartons, or other forms of transport packaging.
Packed beer is stored in the warehouse. It is important to store beer under cover, as sunlight destroys its quality.
In some breweries there is a centralised warehouse where chemicals and other supplies are kept.
Brewery laboratories vary considerably from brewery to brewery. Well-equipped laboratories provide quality control checks on all aspects of raw materials control and use, brewing, fermentation, storage, filtration and packaging. In addition, they can analyse consumer product samples, process water, cleaning water, effectiveness of cleaning procedures, waste water, etc. on a routine basis.
Heat is supplied by a boiler plant, usually located on-site. It can take the form of steam or of water at high temperature.
Boilers are normally fired by oil, natural gas or coal, or supplemented with biogas from the anaerobic waste water treatment plant.
Process cooling is supplied by a central plant using reciprocating or screw compressors. It can be distributed via the cooling media (for instance, ammonia) directly or via secondary cooling media such as propylene glycol.
Water can be supplied from wells or surface intake. If the water is supplied from its own intakes, it should be treated in conventional water treatment plants. Normally the water quality must, as a minimum, meet regulatory requirements for drinking water.
The various water consumers in the brewery have special water quality requirements, typically that it be soft or chlorine-free. Softening plants are regenerated using either salt or acids. Activated carbon filters are normally used to remove free chlorine.
Water consumption in breweries varies significantly. Many breweries have installed water reservoirs and use booster stations for local water supply. Athenian Brewery S.A uses its own supplies of water that are the same for all the beers that Heineken N.V produces.
The CO2 generated during the fermentation process can be collected, cleaned, and then reused in the brewery. CO2 is necessary for carbonation and/or counter-pressure in tanks and bottles to prevent beer oxidation. Some breweries recover more CO2 than is needed for production, in which case the surplus can be sold.
Some breweries use nitrogen instead of CO2 for counter-pressure in tanks and bottles.
Compressed air is mainly used for instruments, actuators, pressurising of tanks, and possibly the transport of spent grain.
Most breweries use public sources of electricity. A few have their own co-generation plants, producing both electricity and heat.
If the electricity supply is not stable, emergency generators may be used.
The existence of a waste water treatment plant will depend on local discharge requirements and the costs of waste water treatment. Relevant waste water treatment technologies involve neutralisation and anaerobic or aerobic processes.
There may be a centralised workshop that machine-tools spare parts, maintains equipment and vehicles, etc. Or workshops may be located near various operations.
Storage for auxiliary materials such as kieselguhr, glue, labels, etc. is ideally located near where the materials are used.
Solid waste is normally collected in a solid waste area equipped with compartments or containers for each type of waste.