How to add priming sugar to beer for carbonation
Customers who are bottling their beer sometimes ask how they should add priming sugar in order to carbonate the beer. There are a few ways to accomplish this.
A first method is to use a large syringe to add priming sugar solution directly to each bottle. This method is the most efficient and least risky in terms of compromising sanitation but care needs to be taken so that you have equal sugar quantities in each bottle or some bottles might be undercarbonated and some might be overcarbonated. In this method (for 5 gallons of beer) a small pot and lid are sanitized by boiling water with the lid on for 5 minutes. Dispose of all but 1/3c of the boiling water and stir in 2/3c (90g) of priming sugar (dextrose) until it is dissolved (for higher carbonation levels 3/4c of dextrose can be used and larger volumes of water can be used as well if you find that easier to work with—see the note at bottom of the paragraph). Bring the sugar solution to a boil and then turn the burner off and with the lid on, let the solution cool down a little so it won't damage the syringe. Then, take a large sanitized syringe and draw the sugar solution up into the syringe (the one in the photo is a 150mL sterile syringes and can be purchased online;
if using the same syringe multiple times, ensure it is fully cleaned and sanitized before and after each use). If air is drawn into the syringe, invert the syringe so the tip is up and tap it gently on the sides so the air bubbles rise to the top then depress the plunger until all the air has escaped. Divide the total volume of sugar solution, by the number of bottles you will be filling. For example, if there is 145mL of solution and 29 bottles, 145/29 or 5mL of sugar solution should be placed in each bottle and the beer then poured into each bottle. For transferring the beer from the fermenter into bottles, a sanitized Fermenter to Keg Racking Hose can be used, with the ball lock disconnect removed and the end of the hose inserted into each sanitized bottle (the ball valve on the fermenter can be used to control flow). (Note: using larger volumes for the sugar solution might require multiple fills of the syringe, but will make adding accurate quantities easier.)
In a second method, priming sugar can be added directly to the fermenter and agitated to mix thoroughly (use the same proportions and sanitary methods for the solution as discussed above). Special care needs to be taken to ensure sanitary conditions throughout. Agitation will likely stir up the yeast which will end up in the bottles and while some yeast of course is necessary for carbonation, too much yeast can contribute off flavors to the beer. Yeast can be minimized by removing the yeast from fermentation out the bottom port of the fermenter prior to adding the sugar solution and agitating. Once thoroughly mixed, the sanitized bottles can be filled and capped using the method discussed above.
For the third method, dissolved priming sugar can be added to a second vessel and then the beer racked into it prior to bottling (use the same proportions and methods for the solution as discussed above). As the beer is transferred into the second vessel, it will thoroughly mix with the sugar to give even distribution throughout. The downside of this method is that it is time consuming, requires a separate vessel, sanitation can be easily compromised and there is extra risk of oxidizing the beer.