Carbonation Conundrum

[dan_s]

Hello Everyone,

I was wondering if anyone could help me with a pattern I’ve been seeing in my beers, lately. I typically brew 5 gallon standard gravity ales (in the 1.045-1.060 range) which sit in primary for a couple of weeks, clear in a secondary vessel for a couple of weeks, and then bottle condition for a month (at around 70*) before I start drinking them, at about the rate of a case a month.

During the first month of drinking, the carbonation is consistent with what I expect from the amount of priming (table) sugar that I add. However, during the second month, I’ve noticed increasingly that some of the bottles pour out with an excessive amount of foam. At this point, my guess is that I’m dealing with either a sanitation issue or a carbonation issue. If it’s a sanitation issue, I would guess that at least some of the bottles would foam up during the first month, but they never do. If it’s a carbonation issue, I would guess that I would see some sort of consistent pattern of under-carbed beers leading to over-carbed beers over the course of the two months, but many of the beers are fine during the second month.

Either way, I’m stepping up my sanitation practices to include soaking the bottles in PBW for a day or two, in addition to my previous routine, which consisted of using a bottle blaster to clean the already surface-clean bottles before using a Vinator to give each bottle several shots of Starsan, which has yielded good results until lately.

Any thoughts appreciated!

[flars]

It is possible that the bottles which seem over carbed or more highly carbonated than other bottles, have been chilled longer before opening. More CO2 will be forced into solution with the longer chilling period. If that is the case you could reduce the amount of priming sugar.

[dan_s]

Thanks, flars - that’s an angle I hadn’t considered. When I chill the beers, I typically put them in the refrigerator six bottles at a time, so in the end, any one bottle is chilled about as long as any of the others, give or take a few days, so I’m guessing that there may be something else at play. Thanks for the suggestion, though.

[hans_caravan]

I’ve had the same issue in the past. Once you can rule out contamination, it’s down to bottling before the beer hits terminal gravity or adding too much priming sugar.

How much priming sugar do you usually use per batch?

[tom_sawyer]

Try using NB’s priming sugar calculator. You’ll be surprised how much less sugar you are supposed to use, especially when a style doesn’t require a lto of carbonation and it was fermented fairly cool so it has quite a bit of residual dissolved CO2. And even doing this, I still find carbonation to be a bit of a crap shoot at times. I deal with it by decanting into a small pitcher that will hold the beer and a genereous amount of foam.

http://www.northernbrewer.com/priming-sugar-calculator/

[dan_s]

Thanks to both of you – to answer both at once, I do vary the amount of sugar I use depending on the style, and I actually use NB’s calculator to determine the amount. I agree 100% that there is definitely a lot of wiggle room in terms of how much carbonation actually winds up in the bottle, even when carbing to style.

Looking back, I realized that I have recently gone from using corn sugar to using table sugar (and have adjusted the amounts accordingly), and that this issue arose after making the switch. I know that the two are supposed to be interchangeable, but might there be some property of table sugar that would contribute to this kind of inconsistent carbing that would not be an issue with corn sugar? I don’t remember having this problem with corn sugar, but that may just be a red herring.

[james_rausch]

Hmmm. Table sugar = sucrose, which metabolizes to glucose and fructose.
Corn Sugar is pure glucose.
They are supposed to be interchangeable, but I do know from cooking with honey which has a lot of fructose, that fructose is sweeter than glucose. Does sweeter= more fermentable? I don’t know, but I’ll look in my old biology and chemistry books and see if I can find anything(unless someone beats me to it).