Gravity and fermentation

[jvend]

Hi, if I want to make an american ale with an OG of 1.052, to be safe. Lets say I want it to have 5.3 abv. So I wait until it reaches a FG of 1.016 and I almost have the 5.3 abv so its acceptable for me, but maybe it can keep on lowering gravity. If I carbonate and then bottle, its going to lower gravity inside the bottle? It will keep on rising abv inside the bottle as well? Will it form the yeast trub at the bottom of the bottle?

 

[Yooper]

Hi, if I want to make an american ale with an OG of 1.052, to be safe. Lets say I want it to have 5.3 abv. So I wait until it reaches a FG of 1.016 and I almost have the 5.3 abv so its acceptable for me, but maybe it can keep on lowering gravity. If I carbonate and then bottle, its going to lower gravity inside the bottle? It will keep on rising abv inside the bottle as well? Will it form the yeast trub at the bottom of the bottle?

Yes, it will keep on going until it's finished and you may have bottle bombs. It's better to know your system and where your beer will finish, and then make the beer the correct OG in the recipe. What I mean is this- I have several recipes that always finish at 1.010.

The thing is, FG is not always that predictable. It is usually very close- 1.010-1.012- but not always 100% predictable. The FG is dependent on several factors, like yeast strain, mash temperature, and fermentability of ingredients. It seems more practical to look at the probably FG, and then determine the OG if the actual ABV means that much. To me, it doesn't matter if a beer is 5.3% ABV or 5.38% ABV as long as the flavor is correct.

But I would highly suggest NEVER bottling a beer that wasn't finished even if you like the SG. That is a very dangerous practice. Let the beer finish, and then bottle it. Most beers will finish at 1.010-1.014 if they are a regular OG with typical ingredients. But not always, and not all beers.

 

[hercher]

If you want to make an American Ale, you will likely finish lower than 1.016. But yes, gravity will continue to lower in the bottle. You will see some sediment at the bottom of the bottle. When you serve the beer, pour it carefully out of the bottle into a glass to leave the sediment behind.

I saw your other post on sparging. May I recommend you take the time to read John Palmer's How to Brew (free here), or even Charlie Papazian's Joy of Homebrewing (there are multiple editions). Both are excellent resources for beginning brewers, though I find Papazian's to be a little more entertaining.

 

[jvend]

Only an approximate value, but once is under 0.014 i dont have to worry about bottle bombs anymore? I guess the best way is wait until the gravity is stable for at least 2 days right?

 

[jvend]

Also. Can a difference of 0.002 cause a bottle to explode?

 

[Yooper]

Only an approximate value, but once is under 0.014 i dont have to worry about bottle bombs anymore? I guess the best way is wait until the gravity is stable for at least 2 days right?

Yes, if the gravity is under 1.014, but still dropping, you most certainly do have to worry about bottle bombs.

The best way is to wait until the gravity is stable for at least 3 days, but also wait until the beer starts to clear a bit as well. Breweries use a "bright tank" so that the beer can fall clear before being packaged. That means less gunk in the bottles, and a cleaner tasting beer.

 

[beergolf]

You can't decide when fermentation is done, the yeast does that. Like the others have mentioned you need to let it go until you are sure that fermentation is done. So assuming that it is done at 1.014 may be dangerous. If it tries to go lower after you bottle, then you have bottle bombs.

Let the yeast do its job, so give it enough time to reach FG and stay there for several days.

 

[jvend]

Yes, if the gravity is under 1.014, but still dropping, you most certainly do have to worry about bottle bombs.

The best way is to wait until the gravity is stable for at least 3 days, but also wait until the beer starts to clear a bit as well. Breweries use a "bright tank" so that the beer can fall clear before being packaged. That means less gunk in the bottles, and a cleaner tasting beer.

Yes but the bright tank in breweries is just to carbonate and usually is very cold, right?

 

[jvend]

If i reach desired gravity, but isnt finished yet, I can pasteurize and thats it right. Then I have my desired gravity and I stop any action of the yeast. By the way whats the least gravity a yeast can get? Near 1.010 and 1.009 right?

 

[hercher]

Pasteurize? There's no need. Let the yeast do its thing, let the beer sit for a few days, ideally in a cold setting, then bottle as usual.

 

[beergolf]

If i reach desired gravity, but isnt finished yet, I can pasteurize and thats it right. Then I have my desired gravity and I stop any action of the yeast. By the way whats the least gravity a yeast can get? Near 1.010 and 1.009 right?

If you are going to bottle you must just let the yeast finish. If you pasteurize, then you would have to add yeast to bottle and fermentation will kick in agin if the brew was not finished. Just let it sit until it is done.

Depending on the recipe and the yeast some brews can go as low as 1.000.

Stop trying to control it and let the yeast do what it does.

 

[Peppers16]

Only an approximate value, but once is under 0.014 i dont have to worry about bottle bombs anymore?

I think you might be underestimating the danger of bottle bombs. There's a good reason people get paranoid about ensuring fermentation is completed, and I'm sure you could find a host of gruesome stories if you look into it. Guessing an approximate 'safe' FG is just a bit too cavalier; much better to know for sure then add priming sugar.

I guess you could say you are underestimating the "gravity" of the situation

And pasteurizing is no better because sweetness in beer is undesirable and you'll strip your brew of any ability to age and mature. I'm not entirely sure why you need to control your alcohol level with such precision but please just don't try to control your ABV through halting at a FG. You control your alcohol through the OG, and nothing else. Ferment it out, then refine your recipe accordingly in future batches