20 October 2011
Home Brewing. The next step: Finishing. When fermentation has stopped or when the specific gravity has fallen close to final gravity it is time for barrelling the ale or, more correctly, casking it, because a barrel is specifically a thirty-six gallon cask. There are not any special precautions that need to be taken when casking, except to ensure that a minimum of air gets dissolved in the beer and that a minimum of yeast and sediment gets carried across.
When fermentation has stopped or when the specific gravity has fallen close to final gravity it is time for barrelling the ale or, more correctly, casking it, because a barrel is specifically a thirty-six gallon cask. There are not any special precautions that need to be taken when casking, except to ensure that a minimum of air gets dissolved in the beer and that a minimum of yeast and sediment gets carried across. This can be achieved by filling the cask by means of a long tube which reaches to the bottom of the cask, always keeping the outlet end of the tube submerged and causing the minimum of turbulence when filling. Needless to say, both the cask and the siphon tubing should be perfectly clean and recently sterilised.
Ideally the casks should be filled quite full, with little or no air space, but this is not usually possible with the casks supplied by the home-brew trade because they are too large. If a significant amount of air space exists at the top of the cask then it may be desirable to purge the air out after a couple of days maturation.
Dry hops, priming sugars, and some types of finings can be added at the time of filling. Priming and fining are acceleration techniques to get the beer info drinkable condition in the fastest possible time. Well brewed ale will usually clear down without the aid of finings and will come into condition without the aid of primings; it just takes longer. Fining is a particularly complex subject and the section on fining should be consulted for further discussion. It is not usual or desirable to fine beers that are destined for bottling.
Ideally the cask should be filled quite full, with little or no air space, but this is difficult to achieve with the casks supplied by the home-brew trade because they are usually much larger than the fermentation vessels that they also supply.
The reasons for requiring the casks to be full are threefold: The first and most important is that we do not want air in contact with the ale during maturation; air is the enemy of sound beer. The second is that a relatively high hydrostatic pressure within the cask assists the clearing process and forces the yeast to sediment faster; rather like the diver in the bottle principle, for those readers who are old enough to remember the little plastic divers that used to fall out of packets of cornflakes. This pressure is difficult to achieve when there is a lot of ullage to compress. The third reason is that valuable potential conditioning gas is lost, filling up and pressurising lots of useless empty space in the top of the cask.
With the casks currently available to us we will have to resign ourselves to the fact that a considerable amount of empty space at the top of the cask is inevitable. Faced with this problem the best that we can do is to ensure that a minimum of air is contained within that space. This is achieved by sealing the cask after filling and allowing it to stand undisturbed for a couple of days or so to allow CO2 pressure to build up. After a suitable standing time the air is expelled by slowly releasing the pressure, either by lifting the safety valve on those casks so equipped or by carefully slackening and re-sealing the cap.
If the cask is equipped with a CO2 injector, this can also be used for the same purpose by giving the filled cask a charge of gas, leaving it to stand for a day to allow the turbulence to sub-side and for the air to diffuse to the surface, and then releasing the pressure as above.
If the cask has a large amount of empty space it is probably beneficial to add priming sugars to encourage a rapid pressure build up. Fifty grams of cane sugar or eighty grams of malt extract would be an appropriate quantity of primings to use for a 23 litre batch.
Dry hopping is the name given to the practice of adding a few hop cones to the cask at the time of filling. This is sometimes done to improve the hop aroma of some beers, normally best bitters and pale ales or any beer that is expected to have a strong hop aroma. Dry hopping does not increase the bitterness of beers, it simply improves the aroma. A couple of cones of the finest aroma type hops, usually Goldings or Fuggles, is added to the cask at the time of filling.
However, I have some doubts about the practice of putting raw hop cones into finished beer, despite the fact that it has been practiced for centuries. Not only does it take some time for the benefit of dry hopping to be felt in the beer, but I feel that it can go past its best and eventually a harsh, astringent flavour is extracted from the hops. This is probably due to tannin and other undesirables being extracted from the bracts and stalks. Also, although raw hops are antiseptic, they are not completely sterile, and I feel that there could be organisms on them that may spoil modem low-gravity beers; although I have no evidence to support that theory.
A popular method of achieving the same effect of dry hopping is to stir a handful of hops into the wort during the last few seconds of the boil, or immediately after the boil, while it is standing in the copper just after the heat has been switched off. The hops are allowed to soak for half an hour or so before draining the copper. This way there is no debris remaining to taint the beer during aging and sterility is also improved.
Priming is the technique of putting a small quantity of fermentable material, either sugars, wort, malt extract, or specialized syrups into the cask or bottles at the time of racking in order to rapidly generate conditioning gas. The residual yeast contained in the beer ferment these additional materials and rapidly produces the carbon dioxide gas necessary for condition. Priming is practiced by many commercial breweries in order to get a beer into drinkable condition as quickly as possible.
One of the reasons that a commercial brewer primes is that he usually opens casks beer to add finings just before the cask is to be delivered the pub. Opening the cask entails a loss of condition and this loss of condition is often restored by adding priming sugars, so that the beer is ready for consumption within a few hours of reaching the pub. Other reasons for priming are that a brewer may have inadvertently allowed a beer to go too flat, or he may wish to change the flavour profile of a particular beer; say sweeten a stout.
In the past only low gravity beers that were brewed for quick consumption were fined and primed. Quality beers, that required a long maturation period, were allowed to condition and clear down unaided. Unfortunately, most modern commercial beers are "running" beers, intended for quick consumption.
The home brewer must choose for himself whether or not he wishes to add priming sugars. Priming is simply an acceleration technique, or a corrective measure for when beers are in danger of becoming excessively flat. A properly formulated and properly brewed beer, kept its proper time, should not need priming. There should be sufficient slowly fermenting residual sugars (dextrins) remaining in the beer after casking to provide secondary fermentation and condition. Almost all beers will come into condition without recourse to priming, it just takes longer.
However, weak beers, particularly those that have greater than about 20 per cent cane sugar in their make-up, may need priming due to a deficiency of residual dextrins. Beer kits and many published malt extract recipes have very high sugar to malt ratios. Some beer kits have an original gravity of only 1034 and the amount of added household sugar specified can be as high as 50 per cent of the total fermentable material. Such ridiculously high levels of cane sugar in a low gravity beer will produce a particularly thin beer with little body and will almost certainly be deficient in dextrins. Beers of this nature will probably need priming to promote condition.
Beers brewed from the recipes in this book, using the methods described in this book, in which the beer is casked shortly after primary fermentation, will not normally need priming. Although it may be desirable to prime if there is an excessive amount of empty space at the top of the cask, or if the cask is opened after an extended maturation period; for the purpose of adding finings for instance.
Beers that have been brewed using the Ken Shales - Dave Line instructions, which advocate keeping the beer under airlock in demijohns for a week or ten days after fermentation, may be too injured to pick-up readily and should be primed as per their instructions.
Of course a home brewer may wish to prime for exactly the same reason that a commercial brewer does; to get the beer into drinkable condition as soon as possible.
Table 1 lists typical priming sugars used by home brewers, which can either be used alone or in combination.
Table 1 Common priming sugars
Referring to table 1, the fast-fermenting sugars will rapidly produce condition but the sugar will be exhausted within a few days. These sugars would be used if the beer is to be consumed almost immediately. If used to excess, fast sugars would put the beer out of balance by drying and thinning it. Dextrose monohydrate is sometimes marketed as "Glucose D".
The medium fermenting sugars will produce condition falrly rapidly, but also contain some slowly fermenting dextrins which will maintain the sugar balance of a beer. The dextrins will provide auxiliary conditioning over an extended period. These would be used if the beer is not yet ready for consumption. Most liquid sugars labelled "brewing sugar" are maize syrups. EDME brewing sugar is a mixture of maize syrup and barley syrup and can also be used in this application. Liquid or dried malt extract can be used.
Malto-dextrin is sometimes marketed as "Burton Brew Body" and is mainly slowly fermentable dextrin which ferment gradually, over an extended period. Its major application is to put some "body" into the cheaper beer kits, but it is also useful as a component in priming sugars. It should be used in conjunction with a fast sugar if immediate condition is required as well as body. To use as a beer kit improver it would be used at rate of about 25 per cent of the cane sugar used; if a kit used 1 kg of cane sugar, then about 250 grams of malto-dextrin would also be added to the fermenter or cask.
Lactose is a non-fermentable sugar derived from milk, and was the sugar traditionally used by the brewing industry for sweetening stouts, milk stouts in particular.
Aspartame refers to the new generation of calorie-free sweeteners which go under various trade names such as: Aspartame, NutraSweet, and Canderel. They are available from chemists and supermarkets. They also can be used to sweeten beers that are expected to be sweet, such as sweet stouts.
Remember that both Aspartame and lactose are non-fermentable and will not provide condition. They should be used in conjunction with a fermentable sugar such as cane sugar or malt extract if you need to promote condition as well as to sweeten.
In general, it will be adequate to prime with SO grams of cane sugar or dextrose monohydrate per 23 litres of "running" or "cooking" beer and 80 grams of malt extract or maize syrup for better quality ales. However, the main sugars can be used in combination with each other for special purposes, thus:
Table 2. Typical combinations of priming sugars
It is best to add priming sugars to the cask as a syrup. This not only ensures that the sugar is sterile, but also ensures that the sugar goes into solution easily. To make a suitable syrup place the appropriate quantity of sugar into a domestic 300 ml coffee mug and top up the mug with boiling water from the kettle, stirring continuously to ensure that the sugar is dissolved. When the sugar has dissolved, cover the mug with a saucer and leave to cool. Malt extract syrups and maize syrups can be treated in the same way. The additional dilution will enable them to go into solution easier. When cool, simply tip the whole contents of the mug into the cask. A number of old brewing texts state that beet sugar is unsuitable for priming: "Beet sugar may entail defective cask fermentation, with faulty fining, and probably ropiness". There was almost certainly some substance to this statement in the days of old because beet would be cov-ered in sugar-loving organisms, but with modern refining techniques I doubt if there is any problem. However, many brewers still traditionally avoid the use of beet sugar. Tate & Lyle is cane sugar; Silver Spoon is beet.
Gyle-worting or gyle-priming is the term applied to priming the beer with actively fermenting wort taken from the fermenter towards the end of fermentation. Stouts were traditionally gyle-primed because they were often a blend of stouts of different ages and the act of adding actively fermenting wort homogenised the blend and improved the flavour, apart from bringing the stout into condition. For some reason it was traditional to allow stouts to go flat before casking, and it was necessary to prime them to get them into condition rapidly. Prior to the first half of this century, priming with sugars was frowned upon by customs and excise, but priming with wort upon which duty had been gauged overcame this problem.
Krausening is the German word for much the same thing. German beers are sterile filtered to improve clarity, but the filtering also removes the yeast. It is therefore necessary to add yeast and fermentable matter for conditioning purposes, but being prohibited from adding sugars the Germans were forced to use a krausen wort. A krausen wort is usually taken from the fermenter in the early stages of fermentation.
It is common practice for commercial breweries to speed the clearing of beers by the addition of colloidial or alginate type substances. A process known as fining.
It is not usually necessary to fine home-brewed beer unless it is particularly troublesome. A well-balanced beer, fermented with a good strain of genuine top-working brewer's yeast, will usually clear down unaided. Commercial breweries fine their running beers because they wish to get them into drinkable condition as soon as possible. Furthermore, the beers get shaken during transportation to the pub, and secondary clearing could take several days.
Fining does improve the shelf life of a beer and greatly reduces the risk of a haze being thrown, which is important to a brewery, but in the home-brewing environment the beer is usually consumed before these problems have a chance to show themselves. Fining does take something out of the beer and decreases palate fullness. Wherever possible, especially in the case of strong old ales and beers for bottling, the use of finings should be avoided. Most beers will clear down unaided. It just takes longer.
There are two types of fining agent available to home brewers:
Gelatine is usually manufactured from the hooves of cattle, and is the simplest of fining agents. It is the most convenient and the most popular form of finings for the home brewer, although it is not often used by commercial breweries. Gelatine is a useful fining agent for home brewers because it is cheap, it is not selective, it is not degraded by poor storage, and is fairly easy to use. However, its fining effect is not particularly powerful when compared to isinglass.
Most home brewers add gelatine finings at the time of casking and this seems to work quite well. However, it is probably better to add it after a short maturation period has elapsed or a few days before the beer is likely to be drunk.
Davis Gelatine is the tool usually employed by home brewers. One 15 gram sachet of powder dissolved in a cup of hot water is sufficient for a 25 litre batch of beer. Allow the solution to cool before using. Place a saucer over the cup to protect it while it is cooling. When the finings are cool, the cask is opened, galf a pint or so of beer drawn off in a jug, the cup full of dissolved gelatine added to the jug and stirred in, and the mixture carefully returned to the cask. If the beer is going to be drunk in a short period of time it may be necessary to add primings at the same time. These should also be mixed in with the beer.
Gelatine finings are also available from home-brew shops ready, that is, in liquid form, usually disguised by the term "Bovine Collagen".
The earliest mention of the use of isinglass for clearine beer was in "Every Man His Own Gauger" published in the year 1695! Isinglass is manufactured from the swim bladder of the sturgeon fish by acid treatment. Isinglass is the fining agent used by British breweries and is much superior to gelatine in both its clearing power, and in its ability to re-fine the beer if it gets shaken during transit. Isinglass has a positive ionic charge and it clears the beer by attracting negatively charged particles to it; rather like a magnet. Yeast cells are negatively charged, so these become attracted to the isinglass.
As you know, like-poles repel. This repulsion effect causes the isinglass molecules to space themselves out evenly through the beer and fall down through it, attracting negatively charged particles on the way; rather like a web. If too much isinglass is used the charge effect can cause the isinglass to be balanced in suspension, causing the opposite effect to that desired, although the treatment must be grossly overdone for this to happen.
Isinglass is not popular among home brewers, partly because it is fussy and is therefore more difficult to use than gelatine, and partly because of its lack of stability. In its liquid state isinglass rapidly deteriorates at temperatures above 20°C, becoming largely ineffective as a result. It should be stored in a refrigerator between 4°C and 10°C. The practice of home-brew retailers storing the stuff on open shelves in warm shops has meant that many home brewers have purchased poor quality "glass", and have had difficulty in using it. Although it may still fine to a limited extent, isinglass degrades into gelatine, and its fining power would be no greater than if gelatine was used in the first place. There are, apparently, some methods of producing isinglass finings that are more stable at ambient temperatures. One hopes that these types are used by the home-brew industry.
Commercial isinglass finings are graded as to the species of donor sturgeon and the area in which it thrives, Karachi, Brazil, Saigon, Indian, and Penang being examples. Each type of isinglass varies in respect to its quality, its temperature stability, its fining power, and its ability to re-fine, Saigon apparently being the best quality. For this reason it is very difficult to provide precise instructions for its use here because we do not know exactly what is in the home-brew bottles. Either too much or too little isinglass will cause Problems. Although it is tempting to suggest following the instructions given on the package, there is no doubt that the instructions given on most home-brew packages of finings are optimistic to say the least. To fine 23 litres of home-brewed beer to commercial standards would require the addition of 150-200 millilitres of good-quality commercial isinglass fining. This is a far greater quantity than is specified on most home-brew packages. Indeed, it is, in fact, more than is actually contained in most packages.
A recent development is the appearance on the home-brew market of powdered isinglass finings which are dissolved in water prior to use. This has a long shelf-life, will not deteriorate during storage, and will certainly solve the stability problem of liquid isinglass. This development may, at last, provide good-quality, commercial isinglass to the home brewer.
Isinglass fining are not usually added until the beer has had some time to mature, at least a week should have elapsed after casking. Isinglass will not work if the yeast count is too high and not ready to drop. It should not be added to beer if the temperature of the beer is above 20°C, nor should the temperature of fined beer be allowed to rise above about 20°C for any length of time. Ideally the temperature of the beer should be lowered as much as possible before the finings are added, say 13-15°C, they work better at lower temperatures, particularly if the temperature is rising slowly. The appropriate quantity of finings should be mixed with some beer (about half a pint for a 5 gallon batch) before being added to the cask, it may be necessary to add primings at the same time if the beer is to be consumed within a short period.
Isinglass finings will normally clear a beer within twelve hours, sometimes as fast as three hours. If a beer is not fining satisfactorily the problem can often be remedied by rolling the cask a few times to get the contents re-distributed and then leaving it undisturbed for a further period.
Auxiliary finings are a special form of finings which remove positively charged particles from our beer - namely proteins and other nitrogenous matter. They behave in the same way as isinglass finings but have the opposite ionic charge. Yeast in suspension is negatively charged and isinglass, being positively charged, is used to remove this. However, haze forming proteins are positively charged and auxiliary finings, being negatively charged, are used to remove these, Auxiliary finings should not be confused with isinglass finings mentioned above. They are not the same thing, and the two are incompatible.
Auxilliary finings are commonly made from alginates, usually Irish moss, and only drag protein out of suspension. They should only be used if your feel that your beer is suffering from a protein haze. It should not be necessary to use auxiliary finings as a matter of course, particularly if Irish moss is used in the boiling stage. Auxiliary finings are usually made from Irish moss, and if Irish moss is used during the boiling phase enough residual extract from the moss should be carried across to final beer to act as auxiliary finings.
Like isinglass, care must be taken in the use of auxiliary finings because an excess will have the opposite effect to that desired and actually stabilise the protein in suspension. It is best to add auxiliary finings at the racking stage of beer production, although they can be added at any stage thought necessary; even to the fermenter. Auxiliary finings should not be added at the same time as isinglass, otherwise they will neutralise each other and nothing will happen. It is usual to add auxiliary finings to the cask at filling, and isinglass some days later. A minimum period of about three days should be allowed between the addition of auxiliary finings and isinglass and vice versa. Auxiliary finings can also be used to neutralise an excess of isinglass fining (and vica versa).
Auxiliary finings are available in home-brew shops, usually as one component of two-part finings. They are usually disguised behind such euphemisms as "seaweed derivative" or "alginate". They should be used as directed.
The home-brew trade supplies fining packages which they refer to as two-part or two-stage.
These are packages containing two bottles of fluid, one of these is auxiliary finings, and the other is either isinglass or gelatine conventional finings. The auxiliary finings are usually conceated behind the euphemism "seaweed derivative" or "alginate"; and the remarks under the heading Auxiliary finings apply to this. The other part, the conventional finings, will be identified as "isinglass" if that is what it is; but it will often be identified as "bovine collagen", or "collagen" if it is gelatine. The remarks above, under the heading gelatine, or isinglass, as appropriate, apply to this. Auxiliary finings are usually part 1 or part A of these dual packages and the conventional finings part 2 or part B.
A maturation period is always necessary after casking or bottling to enable the beer to come into condition. During the maturation period the full flavour of the beer is developed. A number of undesirable, harsh tasting substances are broken down into more mellow substances and various, more volatile, substances come out of solution and are given off to the atmosphere when the cask is vented.
Most commercial running beers are drunk within a couple of weeks of brewing, but home brewed beers will benefit from a much longer maturation period. Stronger beers require more maturation time than do the weaker beers. As a rule of thumb for cask beers, the original gravity of the beer in degrees divided by two, will give a typical maturation period in days. A 1040 bitter requires 40/2 = 20 days maturation whereas a 1060 bitter will require 30 days All beers will benefit from a longer period of maturation and most beers can be drunk in a much shorter time. All bottled beers should be first matured in cask, and then a minimum of a month in bottle However, it is true to say that most commercial low-gravity, running beers are only matured for a week to ten days, fined and sent out to the pub.
Stowing cask ale away for long periods
One of the advantages of home brewing is the ability to stockpile ale for a rainy day. To have a stock of quality ale available at short notice can be quite useful for impromptu parties and the like. Special high-gravity Christmas ales and old ales can be brewed in the spring and matured during the summer in readiness for the winter or the festive season. Classic old nectars, like Russian Imperial Stout, need to be matured in cask for a year or more before bottling. From time to time a home brewer may wish to stow a cask of ale away for a long period.
Any beer of reasonable strength will keep for months in the cask provided that the necessary precautions are taken; strong old ales and barley wines will keep for years. The precautions are that the cask is filled quite full, with just a minimum of head space, just enough to accommodate liquid expansion with temperature; that air is excluded; and that the cask is sealed down tight.
The first of these can prove difficult because the average home-brew cask has a greater capacity than the average brewing boiler or fermentation vessel. If a significant amount of head-space exists in the cask then particular attention should be paid to the purging instructions given elsewhere in this chapter.
It is important to use a high-quality pressure barrel if a high gravity ale is going to be stowed away for a very long period. I tend to use the Ritchie horizontal casks. Three brewings will fill two of these (yes they are that big!).
To guard against loss of condition during storage the cap thread and sealing ring is smeared with petroleum jelly (Vaseline) and screwed down tight. The tap is covered with a polythene bag, secured with an elastic band, to keep bugs away.
If the brew is going to be stowed away for an extended Period, say six months or more, I often fit a spare cap that has no pressure relief valve, the pressure being released manually every couple of days for about a week or until the ale is sufficiently quiet and then then ale is left to mature in peace. However, the lack of a Pressure relief valve does run the risk of damaging the cask, and such foolhardy habits are best avoided by inexperienced brewers.