Question about bottling to naturally carbonate

I'm wondering how it's possible that you can have something finish at a gravity greater than one with some residual sweetness and still feel safe bottling with more sugar (dextrose). How can you be sure the sugars in the original wort won't continue to ferment along with the added sugars and result in exploding bottles?

For instance, if an ale finishes fermenting at 1.004 and 5.8% ABV, then there is certainly some more non-fermented sugars right? Is there a chance that even adding dextrose when you bottle will not kick up enough activity to carbonate? Or is there a difference between the sugars left over from the malts and dextrose and how fermentable they are?

If you hit a 1.004, then you don't have a lot of fermentable remaining.

Many of the remaining sugars are not fermentable which is why they are still there. Beers rarely get down to 1.000, mine typically finish anywhere from 1.012 to 1.018.

Yep, it's very important to note that specific gravity is a measure of the density of the liquid, not a measure of the sugar concentration. Thus, your measurement includes not only sugars, but also every other compound in the solution. If everything in your wort fermented completely, you'd end up with little more than alcohol and water.

That's why you let your fermentation take it's course to the point where you're sure the gravity is not dropping anymore. I just leave it in primary for 2 weeks AFTER I see all signs of fermenation ended. Then you take a hydro reading and if it's anywhere near your expected FG, you're good to go.

Right, what everyone else said...and no, this isn't a shameless postwhore post.

To elaborate...beer yeast can only convert certain sugar molecules into alcohol, and that depends on how long the carbohydrate "chain" is. Malted grain starts out as starch molecules (long-chain complex carbohydrates), and the process of mashing activates enzymes which break starch molecules down (some enzymes break the chains, others "munch" on the ends of the resulting shorter chains) until the chains are short enough that beer yeast can convert them (if I remember correctly, they have to be less than 5 molecules long, but someone else feel free to correct me here).

But this doesn't mean that mashing typically converts every starch into a short enough chain that it can be converted. So what you're left with after fermentation is a certain proportion of sugar chains that are too "long", and thus, remain unfermented even in the bottle...this is why you end up with a final gravity above 1.000.

This is the reason you can sweeten up your finished product by adding maltodextrin or lactose (both long-chain unfermentable carbohydrates) to your beer. I often add maltodextrin powder to chocolate stouts to give them a creamier mouthfeel/weight.

To take it a step further, there ARE wild yeasts and bacteria that can eat longer-chain carbs than beer yeast can. You'll find this out the hard way if you ever get an infection in the bottle. They'll overcarbonate and gush when you open them, perhaps even explode, because all those long-chain sugars that were left over get converted by whatever wild yeast or bacteria got into your beer.

Thanks so much for clearing this up for me. That's pretty much what I assumed was the case, but I was still a bit confused. Maltodextrin.. I'll have to remember that and order some. My Honey Amber Ale could have used a bit of sweetening.

Main reason I asked was because I just bottled my first batch of ale (honey amber) a week ago and it's not yet carbonated at all! It finished at 1.004 and I was wondering if the yeast just pooped out on me and fell out before racking to the bottling bucket. I mixed in the usual 3/4 cup dextrose ask instructed in the bottling bucket. Perhaps carbonation by week two?

Also, I have another batch of Holiday Ale that was started the same weekend as the Honey Amber Ale, both were racked to secondary two weeks after starting. However the Honey Amber completely finished fermenting a few days before racking to the secondary and was ready to bottle after a week in the secondary. Meanwhile my Holiday Ale which started with a lower gravity, is still slowly rolling along weeks after the Honey Ale finished. Both used the same yeast (1054 American Ale) and were fermented at the same temps, yet the higher OG batch finished off super quick... seems strange to me.. I'm wondering how much longer the Holiday Ale will continue to ferment before it's ready to bottle?? Gravity at racking BOTH batches was 1.006. One thing I might note is that the higher OG batch got the yeast from an Activator pack, while the other got the yeast from a Propagator pack. Could that make a difference?

Sorry to go a bit off topic....

simplecj said:

Main reason I asked was because I just bottled my first batch of ale (honey amber) a week ago and it's not yet carbonated at all! It finished at 1.004 and I was wondering if the yeast just pooped out on me and fell out before racking to the bottling bucket. I mixed in the usual 3/4 cup dextrose ask instructed in the bottling bucket. Perhaps carbonation by week two?

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Carbonation can take as long as 3 weeks (sometimes more) to occur; just give it time.

simplecj said:

Thanks so much for clearing this up for me. That's pretty much what I assumed was the case, but I was still a bit confused. Maltodextrin.. I'll have to remember that and order some. My Honey Amber Ale could have used a bit of sweetening.

Main reason I asked was because I just bottled my first batch of ale (honey amber) a week ago and it's not yet carbonated at all! It finished at 1.004 and I was wondering if the yeast just pooped out on me and fell out before racking to the bottling bucket. I mixed in the usual 3/4 cup dextrose ask instructed in the bottling bucket. Perhaps carbonation by week two?

Click to expand...

Yeah, maltodextrin will add body and weight, lactose will add sweetness. Choose your weapon accordingly.

Just give your amber time. No, the yeast wouldn't just "poop out" unless you happened to leave it in the secondary for 6 months...and even then, probably not. A couple questions: First, did you make sure to stir the priming solution into the beer really well? Second, what is the temperature of the room where you are storing the bottles?

1 week is a little early to worry - by week 2 you should get some carbonation and by the 3rd week it should be fine.
i always bottle 3 or 4 in plastic pet bottles so i can judge the carb level just by squeezing the bottle - firm is ready to go

rod said:

1 week is a little early to worry - by week 2 you should get some carbonation and by the 3rd week it should be fine.
i always bottle 3 or 4 in plastic pet bottles so i can judge the carb level just by squeezing the bottle - firm is ready to go

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That's an EXCELLENT idea!!! Kudos!

Evan! said:

Yeah, maltodextrin will add body and weight, lactose will add sweetness. Choose your weapon accordingly.

Just give your amber time. No, the yeast wouldn't just "poop out" unless you happened to leave it in the secondary for 6 months...and even then, probably not. A couple questions: First, did you make sure to stir the priming solution into the beer really well? Second, what is the temperature of the room where you are storing the bottles?

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Ok, so I need to order both maltodextrin and lactose... hopefully no one drinking my stuff is lactose intolerant!

Both batches were well aerated and swirled around after pitching the yeast. The ambient temperature in the room was a bit on the high side of around 73 F but has cooled with the weather to a moderate 70 F as of the last two weeks. That's where my carboys and bottles are stored and I don't really have any alternative locations to put them. For this reason I probably won't ever be able to try out some lagers and stouts and will be limited to ales, meads, ciders and wines...

rod said:

...firm is ready to go...

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That's what she said....