La Cotta
Cotta is the name given to the stage in which beer wort is produced
It is a technique that has remained virtually unchanged over the centuries. What has changed, however, is the equipment: temperature control in the brewing vats and cellars has been improved, and greater attention is now paid to sanitisation.
Even the processing times have remained the same: today’s working day of around 8 hours for a “cotta” is not very different from that of an ancient “cotta.”
The stages of beer wort preparation are milling, mashing and saccharification, filtration, boiling and hopping, cooling and aeration, fermentation, bottling, and refermentation.
Even the processing times have remained the same: today’s working day of around 8 hours for a “cotta” is not very different from that of an ancient “cotta.”
The stages of beer wort preparation are milling, mashing and saccharification, filtration, boiling and hopping, cooling and aeration, fermentation, bottling, and refermentation.
The milling
The grains of barley malt, along with any other cereals used, must be milled in order to make their starch content available.
This step is extremely important, because incorrect milling can cause a range of problems in the subsequent production stages, or lead to undesirable organoleptic characteristics in the finished beer
This step is extremely important, because incorrect milling can cause a range of problems in the subsequent production stages, or lead to undesirable organoleptic characteristics in the finished beer
Mashing and saccharification.
During the mashing stage, the milled malt is mixed with hot water to activate the enzymes contained in the malt. These enzymes require specific temperature and acidity conditions.
There are two mashing methods:
a) infusion mashing: the water/grain mixture is gradually brought to specific temperature levels by heating the mixture.
b) decoction mashing: part of the mixture is separated and brought to the boil, then returned to the main mixture.
Infusion and decoction give beers different characteristics.
Malt contains several enzymes, each with a different function, operating best at different temperatures and acidity levels (pH). The most important are those in the amylase group, which break down the cereal starches into simple sugars.
Mashing and saccharification are therefore a fundamental stage of production, as they represent the moment when the brewer defines the desired basic characteristics of the finished product: body, drinkability, head retention, and so on.
There are two mashing methods:
a) infusion mashing: the water/grain mixture is gradually brought to specific temperature levels by heating the mixture.
b) decoction mashing: part of the mixture is separated and brought to the boil, then returned to the main mixture.
Infusion and decoction give beers different characteristics.
Malt contains several enzymes, each with a different function, operating best at different temperatures and acidity levels (pH). The most important are those in the amylase group, which break down the cereal starches into simple sugars.
Mashing and saccharification are therefore a fundamental stage of production, as they represent the moment when the brewer defines the desired basic characteristics of the finished product: body, drinkability, head retention, and so on.
Filtration
Once saccharification is complete — that is, after the starches have been converted into simple sugars — the mixture must be filtered.
This stage is usually carried out using a lauter tun with a false bottom, which supports the spent grains and allows the sugary wort to be filtered until it is free of impurities.
For an even more effective process, the first wort — which is more turbid — is recirculated through the lauter tun to undergo further filtration
Once the first wort has been extracted, a considerable amount of sugars still remains trapped in the spent grains.
To recover them and increase the efficiency of the production system, hot water is added to the spent grains two or three times, allowing new wort to be collected through further filtration stages.
The importance of this stage lies in preventing the husks of the barley malt and other finer impurities from passing into the wort and reaching the subsequent boiling stages, where they could release tannins and other substances into the finished beer, causing unwanted astringent flavours.
This stage is usually carried out using a lauter tun with a false bottom, which supports the spent grains and allows the sugary wort to be filtered until it is free of impurities.
For an even more effective process, the first wort — which is more turbid — is recirculated through the lauter tun to undergo further filtration
Once the first wort has been extracted, a considerable amount of sugars still remains trapped in the spent grains.
To recover them and increase the efficiency of the production system, hot water is added to the spent grains two or three times, allowing new wort to be collected through further filtration stages.
The importance of this stage lies in preventing the husks of the barley malt and other finer impurities from passing into the wort and reaching the subsequent boiling stages, where they could release tannins and other substances into the finished beer, causing unwanted astringent flavours.
Boiling and hopping.
The boiling of the wort, following filtration, is normally carried out for 60–90 minutes and performs several functions:
– denatures any enzymes still possibly present
– sterilises the wort
– concentrates the wort by evaporation
– promotes, in certain styles, the creation of “Maillard compounds” to give notes of caramel and bread crust
and, depending on the presence of hops during boiling:
– promotes the coagulation and precipitation of proteins and polyphenols
– allows, through prolonged boiling, the transformation of the hop alpha acids into iso-alpha acids, responsible for the bitter component of the beer.
From an organoleptic point of view, hops perform not only a bittering function, but also an aromatic one, thanks to their content of essential oils. As mentioned, the bittering function can only be made possible by bringing the wort to the boil and in any case to temperatures above 96°C; otherwise, the isomerisation process of the alpha acids would not be effective.
– denatures any enzymes still possibly present
– sterilises the wort
– concentrates the wort by evaporation
– promotes, in certain styles, the creation of “Maillard compounds” to give notes of caramel and bread crust
and, depending on the presence of hops during boiling:
– promotes the coagulation and precipitation of proteins and polyphenols
– allows, through prolonged boiling, the transformation of the hop alpha acids into iso-alpha acids, responsible for the bitter component of the beer.
From an organoleptic point of view, hops perform not only a bittering function, but also an aromatic one, thanks to their content of essential oils. As mentioned, the bittering function can only be made possible by bringing the wort to the boil and in any case to temperatures above 96°C; otherwise, the isomerisation process of the alpha acids would not be effective.
Cooling and Aeration.
At the end of boiling, the wort contains several “impurities” due to hop residues and coagulated proteins; the most common procedure for their elimination is the “whirlpool” system, that is, a method of circular movement of the wort that promotes the settling of the solid parts in a single central area of the tun in which the wort is temporarily placed.
The wort is then cooled through a heat exchanger to the temperature suitable for the type of fermentation chosen (top 16–25°C or bottom 7–15°C) and then transferred to the fermentation tanks. After boiling, however, the wort is poor in oxygen, an essential element for the multiplication phase of the yeast mass.
The brewer therefore provides for restoring the necessary amount of oxygen through various methods, such as insufflating pure oxygen or sterile air into the wort, or simply through mechanical aeration (for example, by letting the wort fall into the fermenter from a certain height, or by simply stirring the wort in the fermenter).
The wort is finally ready for the addition of the yeast and the fermentation phase.
The wort is then cooled through a heat exchanger to the temperature suitable for the type of fermentation chosen (top 16–25°C or bottom 7–15°C) and then transferred to the fermentation tanks. After boiling, however, the wort is poor in oxygen, an essential element for the multiplication phase of the yeast mass.
The brewer therefore provides for restoring the necessary amount of oxygen through various methods, such as insufflating pure oxygen or sterile air into the wort, or simply through mechanical aeration (for example, by letting the wort fall into the fermenter from a certain height, or by simply stirring the wort in the fermenter).
The wort is finally ready for the addition of the yeast and the fermentation phase.
Fermentation
Fermentation takes place at a temperature between 18 and 22 degrees and lasts from 4 to 7 days. The tun must be well closed to protect the wort from external agents.
A few hours after the addition of the yeast, the wort begins to “fizz”, producing an increasingly consistent dense foam. This normally occurs 5–15 hours after the addition of the yeast, depending on the type of yeast used. After 24 hours from the addition of the yeast, the foam is removed, taking care to remove all the particles of exhausted yeast without letting them fall back into the wort. And after another 24 hours, the operation is repeated. The final density is about one quarter of the initial one.
After letting the wort rest for a couple of days to make it lose its cloudiness, the beer is ready for the next phase.
A few hours after the addition of the yeast, the wort begins to “fizz”, producing an increasingly consistent dense foam. This normally occurs 5–15 hours after the addition of the yeast, depending on the type of yeast used. After 24 hours from the addition of the yeast, the foam is removed, taking care to remove all the particles of exhausted yeast without letting them fall back into the wort. And after another 24 hours, the operation is repeated. The final density is about one quarter of the initial one.
After letting the wort rest for a couple of days to make it lose its cloudiness, the beer is ready for the next phase.
Bottling
After dissolving 6 or 7 grams of sugar per litre of beer in half a litre of water, and after boiling and cooling it, the beer is transferred into another container of adequate capacity, taking care not to collect the yeast deposited on the bottom.
The sugared water is then poured into the beer and mixed slowly. Then it is bottled, leaving 3–4 cm of air between the beer and the cap (if 33 cl bottles are used), or proportionally for different bottles.
The sugared water is then poured into the beer and mixed slowly. Then it is bottled, leaving 3–4 cm of air between the beer and the cap (if 33 cl bottles are used), or proportionally for different bottles.
Refermentation.
After leaving the bottles for one week in a fairly warm place (20–25 degrees), the beer is transferred to a cooler place protected from light.
After 1 or 2 weeks, the beer will already be clear, with the yeast deposited on the bottom, but it will still have to mature in order to be good. For light beers, from 3–4 weeks to 2 months; for medium beers, 3 months; up to 1 year for “strong” beers.
It can be decided not to filter the beer because in this way the yeast (which has in any case remained in suspension) can pass into the bottles for secondary fermentation. Alternatively, 3/4 of the beer can be filtered, or all of it can be filtered and then yeast can be re-added for refermentation.
After 1 or 2 weeks, the beer will already be clear, with the yeast deposited on the bottom, but it will still have to mature in order to be good. For light beers, from 3–4 weeks to 2 months; for medium beers, 3 months; up to 1 year for “strong” beers.
It can be decided not to filter the beer because in this way the yeast (which has in any case remained in suspension) can pass into the bottles for secondary fermentation. Alternatively, 3/4 of the beer can be filtered, or all of it can be filtered and then yeast can be re-added for refermentation.