Priming Techniques
Once fermentation has finished and your beer has conditioned, it’s ready to drink except for one thing — carbonation. Fermented beer stored at atmospheric pressure retains some dissolved carbon dioxide (CO2), but not enough to provide the “fizz” expected in a beer. The way most homebrewers add carbonation is by transferring their beer to a pressure vessel — a keg or bottles — and adding priming sugar. The sugar is fermented, the CO2 is trapped and this carbonates the beer.
Priming a batch of homebrew can be as simple as adding a standard 3⁄4 cup of sugar to a 5-gallon (19-L) batch of beer, racking it into some bottles, applying a cap . . . and waiting. This is how most beginning homebrewers package their brews as they learn the ropes of making their own beer. But for most homebrewers, the time will come to move beyond the basics and explore the world of beer as you perfect your craft. Priming, as defined in The Homebrewer’s Answer Book by Ashton Lewis (a.k.a. BYO’s Mr. Wizard) is, “the practice of adding sugar to fermented brew before bottling to reintroduce fermentation and carbonate the brew in bottle.” On our quest to discover the many styles of beer and advance from making good beer to making great beer, it often becomes necessary to take a closer look at even the simplest aspects of brewing — priming included.
Upon close examination of the process of priming your beer there are several questions that may arise. What are the different methods of priming beer? What is the appropriate level of carbonation for a given style of beer being brewed? What type of fermentable sugars can I use for priming? How much priming sugar should I use and how should it be prepared? Is a different approach necessary when priming beer that is destined for a keg instead of a bottle?
Priming with sugar
There are several approaches to priming a batch of beer that vary by both complexity and ingredients. The simplest method, outlined at the beginning of this article, is to add a certain amount of refined sugar to achieve a target level of carbonation. To do this accurately, you need to take into account the carbon dioxide already dissolved in the beer, which can be estimated from the temperature of the beer. More gas dissolves into cold liquids than into warm liquids.
The basic process of using anhydrous glucose, glucose monohydrate (two forms of dextrose a.k.a. “corn sugar”) or sucrose (a.k.a. “cane” or “beet” sugar) to prime a batch of beer destined for bottles can be found on the Brew Your Own Web site at http://www.byo.com/referenceguide/primingchart/. This chart allows you to determine the amount of priming sugar needed to hit the desired level of carbonation. Typical carbonation levels by beer style are also given to provide a guide to determine a target to shoot for. If you ferment 5.0 gallons (19 L) of ale at 70 °F (21 °C) and add 0.75 cups of corn sugar (glucose monohydrate), which weighs about 4 oz. (113 g), you will yield about 2.2 volumes of CO2 — an amount at the top of the scale for most English-style ales and at the bottom for most American-style ales.
If you are wondering what volumes of carbon dioxide are, volumes are a means of measuring CO2. Because all beers range in carbonation levels, one way to measure those levels is by volume. Most beers have around 2 to 3 volumes of CO2 and the most common measure is 2.5 volumes. Volumes of CO2 do vary significantly by style, however. For example, some British ales can have 1.5 volumes, which may seem nearly flat, while some Belgian-style ales can reach up to 4 volumes — and German weizens can be anywhere from the average 2.5 all the way up as high as 5 volumes. You can also measure CO2 on a scale of grams of carbon dioxide per liter of beer. The average carbonation level of 2.5 volumes is roughly 5 grams per liter, 2 volumes is about 4 grams and 3 volumes is about 6 grams per liter. Refer to the chart on page 64 for some common styles and their levels of carbonation.
After determining the desired amount and type of sugar needed, bring a pint of water to a boil, remove from the heat source and slowly add the sugar to the water, stirring to dissolve. Bring the solution back to a gentle boil for 15 minutes to sanitize it, cover and let cool. This process can be accelerated with a cold water bath. Then add the sugar solution to a sanitized bottling bucket and rack the finished beer into the bucket before transferring the primed beer into sanitized bottles and capping them with sanitized caps. If you rack the beer into the priming sugar, it should dissolve evenly. If you add the sugar to your beer, you should stir it lightly for even distribution. To use this method of priming when packaging beer in kegs, simply use half as much priming agent as necessary for bottling.
When you rack the beer to your bottles, put a cap over each bottle as quickly as is feasible. Then after you have filled a few bottles, crimp the caps. The less oxygen you expose your beer to during bottling, the better.
Priming with PrimeTabs™
Another fairly simple approach to priming is the use of PrimeTabs™ and Cooper’s Carbonation Drops. These are sugar tablets that can be added to bottles containing beer right from the secondary fermenter. The tablets are proportioned so that a set amount of the tablets in a twelve ounce bottle produce a specific level of carbonation. (See the carbonation priming chart for information regarding volumes of CO2). For example, three PrimeTabs™ per twelve ounce bottle would provide a degree of carbonation a little over two volumes of CO2, and four or five tablets would result in a level of carbonation close to three volumes of CO2 similar to the level of carbonation in most American lagers. The greatest advantage of the Cooper’s drops and PrimeTabs™ is the convenience of not having to measure or boil a sugar solution and mix it into the beer in a separate vessel. The finished beer may be racked directly from the secondary fermenter into bottles and then the desired number of tablets added to each bottle prior to capping.
Priming with malt
But what if you wish to make a truly “all malt” beer instead of one primed with non-malt sugars? Priming with malt is most certainly an option, depending on how you wish to prepare the malt to do the job. The easiest method of priming with malt is to prepare a solution of dried malt extract in the same manner as for dextrose or sucrose. However, since dried malt extract is not equal to dextrose or sucrose in terms of extract weight or fermentability — and the resulting production of carbon dioxide — you will need to use a greater amount of malt extract than sugar to achieve the same degree of carbonation. Therefore, it takes more dried malt extract (DME) to provide the same priming power of dextrose. As a rough guide, 1.25 cups of dried malt extract would be the equivalent of 1 cup of regular corn sugar (glucose monohydrate). (The exact amount would vary with the fermentability of the extract.) If you plan to use liquid malt extract (LME) instead of dry malt extract, you will need to use 1.15 times as much LME as DME to account for the 15% difference in moisture content between LME and DME. If you are using LME, it would be better to weigh it out rather than measure it by volume.
Another method of priming with malt is to reserve some fresh wort (gyle) from a batch of beer being brewed and store it cold in a sanitized container to be added back at priming time. This particular method is not recommended for bottling as it is more difficult to precisely determine the fermentability.
A similar yet also tenuous method for an average homebrewer (and therefore limited to kegging rather than bottling) to prime beer is to package the beer before fermentation is complete. If a particular recipe is known to finish at a certain specific gravity, the vessel could be closed before that final specific gravity is reached, allowing the remaining sugar to ferment in a closed vessel to provide the necessary carbonation.
Priming with this technique requires careful monitoring of specific gravity as fermentation proceeds in order to transfer the beer from fermenter to keg at the proper time. Once kegged, the pressure must be closely monitored, and any excess pressure relieved as necessary until fermentation is complete.
Kräusening
Last, but most certainly not the least method of priming your brew, is the traditional method known as “kräusening.” Kräusening is performed by adding beer that is at “high kräusen,” or peak activity, of primary fermentation to a finished batch of lager beer.
The still-fermenting dose of beer adds both sugar and active yeast to a batch where fermentation is otherwise complete, providing the final amount of carbon dioxide to carbonate the beer. Kräusening has the same issues as priming with gyle or packaging a still-fermenting beer in that it is difficult to determine precise fermentability of the priming agents involved.
This method should also be reserved for kegging rather than bottling, as the final level of carbonation is difficult to determine precisely with equipment available to the average homebrewer. This method of priming may be particularly suited to a high gravity beer where a fresh infusion of yeast at the end of normal fermentation will not only carbonate the beer but help condition it as well. The conditioning of the beer by the yeast may help reduce diacetyl (i.e. butterscotch), hydrogen sulfide (i.e. rotten egg) and acetaldehyde (i.e. green apple) that may be present in the beer. While this conditioning is carried out by the yeast regardless of the method of priming, kräusening supplies yeast at peak activity along with unfermented sugars from the malt to help them do the job.
Conditioning
Once the beer is primed, you want the yeast to ferment the sugar as quickly as possible. As such, it helps to keep your bottles in a warm location for awhile after bottling. If you can hold the bottles at 75–80 °F (24–27 °C), the refermentation should occur in three to four days for regular-strength ales. (For strong ales or lagers, the health or density of yeast is likely less and bottle conditioning may take longer). Because such a small amount of sugar is being fermented, you don’t have to worry that the warm bottle conditioning will make your beer estery, as it would be if you fermented the entire batch warm. Once the yeast has consumed the sugar, store the bottles in a cool location — preferably refrigerated — a few days before serving.
Priming your homebrew can range from using a simple scoop of table sugar to the traditional method of kräusening. If you are ready to advance beyond the basics, it may be time to take another look at this final step of the brewing process.
