Packaging

Packaging is the transfer of your mixed fermentation/sour/funky beer from a fermentation or aging vessel into the the final package (e.g. a bottle or a keg). This page will discuss various things one should consider such as when to package, how to package and what final package to put the beer into.

When to package

(in progress)

Final Gravity

There is no hard and fast rule for when to package based on final gravity because the gravity of the finished beer will depend on recipe, process and microbes present among other factors. Generally lower final gravities are safer because they constrain the extent to which the beer can continue to ferment and generate extra CO2 in the package. But rather than looking for a specific number, pay more attention to the stability of the gravity. Jay from the Rare Barrel recommends waiting at the final gravity for 2-3 months in mixed fermentation beers to ensure that this gravity is the actual final gravity (~38 minutes in). If the gravity is stable over a long time scale (weeks to months, depending again on factors such as recipe, process and microbes present), then the beers is probably done. If you are unsure then give the beer a bit longer and monitor final gravity. Each gravity point (.001) of continued fermentation yields roughly 1/2 volume of CO2.

Clarity and pellicles

Beer with Brettanomyces and bacteria, as well as certain Saccharomyces strains, will take longer to clear than other beers. Generally time can take care of most of the clarification in mixed fermentation beers with long aging times. Faster turnaround beers or kettle sours may not clarify by time alone. The level of clarity you are looking for before packaging will depend on your preferences and the beer you are making. Beer can be packaged without good clarity and they will continue to settle out in the bottle, but note that beers with high carbonation levels may kick the sediment back into suspension, which may or may not be what you want in your beer.

Some producers will coarse filter their fruited or dry hopped sour beers to prevent pieces of fruit from clogging equipment or making it to the package

Beer with a pellicle can be bottled and it is not necessary to wait for a pellicle to disappear before bottling.

How to package

Re-yeasting

When bottling or priming a keg at packaging time, the brewer should consider re-yeasting. In a long aged beer, especially an acidic beer, the Saccharomyces will mostly be dead already. This leaves Brettanomyces in charge of conditioning the beer. Although some lactic acid bacteria are capable of producing CO2, their contribution is probably negligible. It is also possible that homofermentative LAB will consume a portion of the sugar before the Brett has a chance to produce CO2. Re-yeasting is a very effective way to ensure proper CO2 levels in an aged sour beer. Another benefit of re-yeasting is that it tends to help avoid (or minimize) Tetrahydropyridine production.

Commercial producers and MTFers have had success re-yeasting with their mixed culture, wine yeast, and champagne yeast. The specific yeast you choose is up to you, and we recommend that you try a couple different yeasts out to find the one you prefer. When re-yeasting at bottling, it is not recommended to add new highly attenuative yeast to make sure that the bottling yeast you add cannot ferment additional carbohydrates remaining in the beer (~41 minutes in). Re-yeasting with a yeast that beer has already seen should eliminate the possibility of continued attenuation as long as the beer is already at final gravity.

The yeast required for carbonation is very little. A good rule of thumb to use is to use 10% of the yeast that you would normally use for a primary fermentation. For example, for dried yeast use ~2 grams of yeast for 5 gallons of beer . Rehydrating the yeast is recommended. See Jeff Crane's "Blending Calculator" (extension of Michael Tonsmeire's "Blending Calculator") for a re-yeasting and priming calculator.

Many wine yeast strains are known to be "killer" yeast strains. In Saccharomyces, killer strains produce toxins that kill sensitive strains. Neutral strains do not produce toxins, nor are they killed by them . Almost all ale and lager strains are sensitive to the toxins produced by killer strains . In Saccharomyces, four toxins have been identified: K1, K2, K28, and Klus, the first three of which can only kill other strains/species of Saccharomyces. The Klus toxin has been found to kill yeast from other genra, such as Hanseniaspora spp., Kluyveromyces lactis, Candida albicans, Candida dubliniensis, Candida kefir and Candida tropicalis, and the K1, K2 and K28 killer strains of S. cerevisiae . However, none of the toxins have been found to kill Brettanomyces . The K1 toxin is most active between a pH of 4.6 and 4.8, while K2 and Klus are active around a pH of 4.0 to 4.3 .

This tends to create some fears for brewers who believe that the Saccharomyces strains in their beer might still be alive. However, in a highly acidic sour beer, Saccharomyces tends not to live for extended periods of time. Even if some cells do, their activity would be next to none due to no available sugars left in the beer (other than priming sugar), and thus their contribution to the flavor development of the beer would be minimal to none. Fear of autolysis occurring due to killer strain activity is usually unfounded because most of the Saccharomyces cells are left behind and the ability of Brettanomyces to use the acids and proteins that are released during whatever autolysis might occur in the bottle. Re-yeasting with wine yeast for priming has the additional advantage of not fermenting maltose or maltotriose, so unexpected attenuation from the wine yeast will generally not occur as long as the beer is already fully attenuated. Flavor impact by the wine yeast is also probably not significant due to the small amount of fermentables provided by the priming sugar. Thus, there is little argument against re-yeasting with wine yeast at packaging time.

• Lallemand chart of wine yeasts and their Killer Factor.
• Chris Lewis's write up on wine yeast character/Killer Factor on Lewy Brewing Blog.
• Shea Comfort notes on wine yeast on the BBB.

Priming

(in progress)

See Jeff Crane's "Blending Calculator" (extension of Michael Tonsmeire's "Blending Calculator") for a re-yeasting and priming calculator.

Oxygen exposure

Oxygen is the enemy of finished beer, and most producers of standard beers invest a lot of time and money to reduce oxygen exposure in their finished beer. For mixed fermentation/sour/funky beers, this may not be as significant a concern. These beers, especially barrel aged versions, generally have more oxygen exposure during fermentation and aging and this contributes to the characteristics of the beer. Some brewers achieve good results without purging bottles before filling (for exaple, lambic producers and blenders), and others do take care to avoid oxygen exposure in the packaging process. There is no definite answer in terms of whether it is better to carefully CO2 purge as is recommended in more normal beers or if the yeasts present in mixed-fermentation beers are better able to quickly scavenge O2 before it can damage the beer, though excessive oxygen exposure can hurt your beer (either permanently through formation of acetic acid and/or ethyl acetate, or temporarily by influencing tetrahydropyridine (THP)). Based on your experience, equipment, and preferences, you can determine how much to limit O2 exposure in your beers. The safest route is to treat them as you would a normal beer and take care to avoid O2, though the experience of some will say that this extra work and cost is not necessary.

Package and closure types

(in progress) Many sour/funky/mixed fermentation beers are highly carbonated. It is recommended to package highly carbonated beers in bottles of thicker glass which can better withstand higher pressure (e.g. many Belgian and German bottles, corkable Champagne-type or 'fat-lipped' Belgian-type bottles, etc.). This is especially true if you feel the beer may continue to carbonate in the bottle from residual carbohydrates beyond the priming sugar you added. Be careful when carbonating your beer to high volumes to ensure that your chosen package can handle this pressure.

• Crown caps (26 mm) - A variety of thicker glass/high-pressure bottles are available in the standard 26 mm cap size. No special equipment, beyond a normal capper, is necessary to fill bottles of this type. It may be necessary to swap the metal plates on cappers such as the Emily capper to accomodate the wider neck on some bottles taking a 26 mm cap (such as champagne-style bottles with 26 mm caps (e.g. Logsdon, Goose Island, some Upright) and the 375 mL crown finish bottles modeled after the 'Vinnie' 375 mL bottles).
• Crown caps (29 mm) - For capping bottles with 29 mm openings (such as Champagne-style bottles and 375 mL half-Champagne bottles), you will need to source a 29 mm bell and 29 mm caps, which are non-standard. Many 29 mm bottles are both capable and corkable. For cork and capping, see below.
• Swing tops - Many swing tops are thicker glass and are therefore well suited for higher carbonation beers. Swing tops also allow for easy venting of carbonation if the beer carbonates more than desired/anticipated. Due to the soft gasket (and possibly plastic top piece holding the gasket for some bottles), the same concerns regarding cleaning difficulty and cross-contamination apply to swing tops as to other plastic parts used after the hot side when brewing both normal and 'funky' beers. If you don't want your normal beers exposed to the micro-organisms in your funky beers, we recommend not using the same swing tops for bottling both types of beer, jusrt as we recommend keeping seperate sets of plastic equipment used for fermentation and transfer of fermented beer when brewing both clean and 'funky' beers. Some express concern about long term aging in swing tops and the possibility of swing tops not being as impermeable a barrier to O2. If you are concerned about this they it may be better to not use swing tops for long aged beer. At this time we are unaware of any comparisons of swing tops and other closure mechanisms regarding their susceptibility to O2 transfer during extended aging to give a firm answer as to whether swing tops allow more O2 ingress than other closures or not .
• Cork and cage - Corking and caging can be used for both champagne-type bottles and the brown glass 'fat-lipped' Belgian bottles, both of which are generally thicker glass and rated for higher CO2 pressure. Generally corking and caging is used for bottles with 29 mm openings, though some have cork and cage finished bottles with 26 mm openings. Make sure your bottle can take corks before using it. Corking and caging does require some more special equipment. Most wine corkers are designed to push the cork all the way into the bottle, which is not what you want. Brewers will at least want a floor corker for standard wine bottling, which can be modified to control the cork depth. Bench corkers such as the Colonna capper/corker work as well. Champagne floor corkers are available and make this easier, though they are more expensive. It is difficult to control the exact depth of the cork with a two arm corker, and we do not recommend this for corking and caging. The following gives a step by step process for corking and caging with a non-champagne floor corker. For a more detailed description with pictures, see Dave Janssen's blog post about corking. The more common floor corkers work by both compressing the cork and pushing it into the bottle with the movement of the arm. In order to leave the cork partly exposed, and to control the exposed cork level, place a standard carboy bung on the rod which pushes the cork. This positioning can be adjusted as needed. Push the cork into the bottle until you reach the bung, then bring the arm all the way up. Remove the bung and lower the spring-loaded pedestal holding the bottle. Then, while holding the bottle with one hand, lower the corking arm completely and bring the bottle down, letting the cork be pushed fully out of the compression section of the corker. Play around with cork depth to find the right amount for you for ease of removal based on your corks, bottles and carbonation levels. The amount of cork sticking out should be more than how it appears when it is caged, as the cork is vertically compressed or 'mushroomed' during the caging process. This mushrooming can be accomplished by hand, though be aware that flaws in the bottle may cause the neck to break, which would be a very dangerous situation if you are applying the downward force by your hand. It can more easily and safely be applied with a bench capper. Put the cage on the cork and compress both with a bench capper. Hold the bench capper arm in place with your shoulder/armpit, leaving both hands free to orient and twist the cage. Special cage twisting tools are available, though sharpies or some interchangeable screwdrivers are about the right size. You could also use twist lock pliers if you have them around.
• Cork and cap - Corking for cork and cap closures can also be used on champagne-style bottles, which are a good source of high-pressure bottles for brewers. Corking and capping is much more straightforward as the cork is pushed entirely into the bottle. Generally cork and cap closures are used on bottles with 29 mm openings, though some have done this with 26 mm bottles. Make sure your bottle can handle corks before using them for a cork and cap finish. Although the cork depth is not as important as in corking and caging, the cork still must be far enough into the bottle to not interfere with the cap. Bench corkers are recommended for corking and capping as they allow better control of cork depth than two arm corkers and bench corkers allow the cork to be easily depressed further if it is not far enough into the bottle. For 29 mm bottles, you will also need a 29 mm bell and 29 mm caps for capping.
• Kegging - Kegging offers the benefit of being able to force carbonate or naturally carbonate with adding priming sugar and (optionally) re-yeasting. If force carbonating, follow the same procedures that you would for any other beer. Consider the "set and forget" method of force carbonating, which requires 1-3 weeks. This will allow the beer to settle while also dialing in the carbonation level. Priming in the keg often produces great results with sour beers. Generally, use 1/2 of the priming sugar that you would normally use, or excessive foaming can occur . If re-yeasting, which is generally recommended (see the Re-yeasting section above), use 10% of the yeast you would normally use to for a primary fermentation. For example, use around 2 grams of dried champagne yeast re-hydrated to naturally carbonate 5 gallons of beer . Priming in the keg will result in a little more sediment at the bottom of the keg, but this will be pulled out on the first pour from the keg. Allow at least three weeks of conditioning at room temperature, and then a week at refrigeration temperatures before serving. If the keg is not re-yeasted, it might take considerably longer than three weeks to carbonate the beer depending on the vitality of the yeast in the beer. The brewer should consider keeping plastic kegging equipment such as serving lines and taps separate from kegs that serve clean beers.
• Green glass v Brown glass - Some bottle types, especially champagne style bottles, may be more available in green glass compared to brown glass. Green glass does a worse job shielding the beer from UV spectrum light, which can interact with hop compounds to produce 'skunky' or lightstruck flavors and aromas. Many classic Belgian mixed fermentation beers are found in green glass, and some producers in North America seek out green glass over brown glass for their beers (~11 minutes in) (also, Bob Sylvester).
• Crown caps v corks -
• Large format bottles -

See Also

Additional Articles on MTF Wiki

• Aging and Storage
• Tetrahydropyridine
• Floor Corker
• Mixed Fermentation
• Funky Mixed Fermentations
• Spontaneous Fermentation

External Resources

• Blending and Priming Calculator, by Jeff Crane.
• Carbonation in Sour Beers, Sour Beer Blog.
• Brewing Sour Beer At Home, by Michael Tonsmeire (see the "Bottling" section).