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Over Carbonation in Bottle

Paul_G

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I'm trying to get to the bottom of a problem which has me stumped.  If I brew a light beer such as a wheat beer and bottle condition it then all is well.  If I brew a dark beer such as an oatmeal stout then after two weeks of bottle conditioning all is well but if it's left for a longer period of time then it over carbonates.  Even if I refrigerate it before opening it will gush up after the cap is removed and loose about 2/3 of the contents.  The remaining beer tastes ok so I'm convinced that it isn't an infection.  All my equipment and bottles are well sanitised with Star San.

The malt bill for one batch which over carbonated was:

4Kg of pale malt
0.2Kg of Crystal Malt
0.2Kg of Chocolate Malt
0.1 Kg of Black Malt
0.5Kg of Malted Oats

The mash temperature was 68C (154F) for 90 minutes then a 60 minute boil followed by cooling down to around 20C (70F) through a plate chiller.  The yeast used was White Labs WLP028 Edinburgh Ale.  This was in the primary fermenter for 7 days then transferred to the secondary fermenter for 14 days.  Both primary and secondary fermentation were conducted in a temperature controlled cabinet at 19.5C (67F).  The OG was 1.053.  Gravity after primary was 1.017 and after secondary it was steady at 1.016.  I had 18 litres to bottle so I used 70g of sugar made into a syrup into the fermenter to give a carbornation of 1.8.

After two weeks of bottle conditioning at room temperature I opened a bottle and all was well however a few weeks later it was gushing when opened.  I've tried WLP007 English Ale yeast and 4 weeks in the secondary fermenter but neither solved the issue.

Any suggestions?
 
I hate to burst your bubble, but gushers usually result from an infection.  I would open a few bottles and degas the remaining beer before taking another hydrometer reading on the residual.  If it is significantly low, like below 1.010, this is where I would first focus.

Beyond that, you may not be actually reaching your final gravity.  Perhaps the yeast is stalling out and the addition of a little oxygen and simple sugars is causing a refermentation strong enough to reach a lower gravity.  This could explain why you are not picking up any off-flavors.  If you end up with a degassed gravity reading of 1.012 to 1.014, this might be the culprit.

Otherwise, there would not be enough sugars added if you are aiming for a 1.8 vols of CO2 to cause gushers.
 
Oginme said:
I hate to burst your bubble, but gushers usually result from an infection.  I would open a few bottles and degas the remaining beer before taking another hydrometer reading on the residual.  If it is significantly low, like below 1.010, this is where I would first focus.

Beyond that, you may not be actually reaching your final gravity.  Perhaps the yeast is stalling out and the addition of a little oxygen and simple sugars is causing a refermentation strong enough to reach a lower gravity.  This could explain why you are not picking up any off-flavors.  If you end up with a degassed gravity reading of 1.012 to 1.014, this might be the culprit.

Otherwise, there would not be enough sugars added if you are aiming for a 1.8 vols of CO2 to cause gushers.

Most gushers I've made have been accidentally putting too much sugar. Infections do happen but are rare if you sanitize well and boil right.
 
Hi Oginme.

Thanks for that feedback.  I don't have any of that batch left but I have some from an imperial oatmeal stout that I brewed which also has the same problem.  I opened a bottle of it and again it gushed.  This is the third one which has gushed from this batch but the bottles opened not long after the 2 weeks bottle conditioning did not.  The beer was clear with no off smells or flavours.  I measured the gravity of what was left in the bottle and the readings stack up as follows:

Gravity into fermenter = 1.094
Gravity after primary = 1.026
Gravity after secondary = 1.023
Gravity of beer from gushing bottle = 1.020

This has got me wondering if my fermentation stalled and that the sugar i used for carbonation plus the drop of 0.003 in gravity is why it is so fizzy.  If this is the case I need to work out why it only happens to my dark beers.
 
Paul_G said:
Hi Oginme.

Thanks for that feedback.  I don't have any of that batch left but I have some from an imperial oatmeal stout that I brewed which also has the same problem.  I opened a bottle of it and again it gushed.  This is the third one which has gushed from this batch but the bottles opened not long after the 2 weeks bottle conditioning did not.  The beer was clear with no off smells or flavours.  I measured the gravity of what was left in the bottle and the readings stack up as follows:

Gravity into fermenter = 1.094
Gravity after primary = 1.026
Gravity after secondary = 1.023
Gravity of beer from gushing bottle = 1.020

This has got me wondering if my fermentation stalled and that the sugar i used for carbonation plus the drop of 0.003 in gravity is why it is so fizzy.  If this is the case I need to work out why it only happens to my dark beers.

It's possible you woke up the yeast, that seems a bit under fermented.
 
I'm with Oginme. Priming for 1.8 volumes, even factoring in a 3 point drop after bottling wouldn't be enough to cause gushers. I really think an infection is the culprit.

I use Starsan exclusively for sanitizing and have never had an infected beer, but have read several post from people I trust who, at least periodically, switch to Iodphor to keep the risk of infections down. Also to sanitize suspect equipment. If your fermenters have scratches and/or nicks they are definitely suspect.

Even if it turns out not to be the problem, an extra thorough cleaning and sanitizing is not a waste of time and may prevent problems in the future.
 
BOB357 said:
I'm with Oginme. Priming for 1.8 volumes, even factoring in a 3 point drop after bottling wouldn't be enough to cause gushers. I really think an infection is the culprit.

I use Starsan exclusively for sanitizing and have never had an infected beer, but have read several post from people I trust who, at least periodically, switch to Iodphor to keep the risk of infections down. Also to sanitize suspect equipment. If your fermenters have scratches and/or nicks they are definitely suspect.

Even if it turns out not to be the problem, an extra thorough cleaning and sanitizing is not a waste of time and may prevent problems in the future.

"switch to Iodphor to keep the risk of infections down."

Why would you do that not like star san would not be good enough, I soak everything in PBW, then soak it with Star San After a good rinse, this just helps with strange odors and keeping stuff from discoloring.
 
Greetings Paul_G - I?m going to agree with Oginme and Bob.  However, I would like to ask some questions that may seem obvious, but here goes:

1) Can we assume the batches you have issues with reached their FG?  If not, than they may be completing fermentation in the bottle.  I find it difficult to fathom that 1.8 volumes of carbonation could possibly cause gushers.

2) What are you using to measure gravity?  A hydrometer is the only practical measuring device to use after fermentation has begun.

3) Could the fact that this occurred in dark vs. light beers be a coincidence or could there have been a sanitation issue with the bottles you used for the dark beers?

It?s the dark vs. light thing that?s most perplexing.  I?m leaning toward the dark vs. light as being a coincidence.  I?m also leaning toward an issue with the bottles themselves.

Once you finally figure out what has caused this phenomenon, please share your experience with this group!  ;)

Good luck!
 
Ck27 said:
"switch to Iodphor to keep the risk of infections down."

Why would you do that not like star san would not be good enough, I soak everything in PBW, then soak it with Star San After a good rinse, this just helps with strange odors and keeping stuff from discoloring.

The thought is similar to antibiotic resistance in bacteria.  Using a single type of sanitizer kills teh majority of bacteria which may exist, but a small proportion may survive, even if they are severely diminished in numbers.  Switching sanitizers (assuming they are different types) periodically should help to kill off any bacteria which have become resistant to the attacks of the primary sanitizer. 
 
Oginme said:
Ck27 said:
"switch to Iodphor to keep the risk of infections down."

Why would you do that not like star san would not be good enough, I soak everything in PBW, then soak it with Star San After a good rinse, this just helps with strange odors and keeping stuff from discoloring.

The thought is similar to antibiotic resistance in bacteria.  Using a single type of sanitizer kills teh majority of bacteria which may exist, but a small proportion may survive, even if they are severely diminished in numbers.  Switching sanitizers (assuming they are different types) periodically should help to kill off any bacteria which have become resistant to the attacks of the primary sanitizer.

very interesting!
 
Oginme said:
Ck27 said:
"switch to Iodphor to keep the risk of infections down."

Why would you do that not like star san would not be good enough, I soak everything in PBW, then soak it with Star San After a good rinse, this just helps with strange odors and keeping stuff from discoloring.

The thought is similar to antibiotic resistance in bacteria.  Using a single type of sanitizer kills teh majority of bacteria which may exist, but a small proportion may survive, even if they are severely diminished in numbers.  Switching sanitizers (assuming they are different types) periodically should help to kill off any bacteria which have become resistant to the attacks of the primary sanitizer.

I always thought that because Star San is acid based that it pretty much would kill anything and nothing could really build immunity. Huh.
 
Hi KellerBrauer,

1) I'm hitting the FG numbers that Beersmith is predicting.

2) I use a refractor along with Beersmith to correct the reading for fermenting wort.  I zeroed it with distilled water and calibrated it against a hydrometer.

3) I always sanitise the bottles with Star San using a vinator to squirt up inside the bottles.  I've even had the problem with brand new bottles which were sanitised.

The same kit has been used for light and dark beers along with the same sanitisation regime.  I've brewed light beers between the dark beers and they've been fine whilst the dark beers have over carbonated.
 
Paul_G said:
Hi KellerBrauer,

1) I'm hitting the FG numbers that Beersmith is predicting.

2) I use a refractor along with Beersmith to correct the reading for fermenting wort.  I zeroed it with distilled water and calibrated it against a hydrometer.

3) I always sanitise the bottles with Star San using a vinator to squirt up inside the bottles.  I've even had the problem with brand new bottles which were sanitised.

The same kit has been used for light and dark beers along with the same sanitisation regime.  I've brewed light beers between the dark beers and they've been fine whilst the dark beers have over carbonated.

You are either using some really really really crazy yeast or are using too much sugar or something sounds way to crazy to be a infection.
 
So, just doing a little bit of back of the envelope calculation.  The amount of sugar for carbonation to 1.8 volumes if added to the recipe would give an increase in OG of about 0.001 points.  So, if your gravity at bottling is around 1.023, add a point for the sugar you just out in and you get 1.024.  You are now reading 1.020 so that is a difference of .004 points.  This would give a carbonation rate of about 4.4 volumes equivalent of sugar added. 


Kinda getting into bottle bomb range for standard long necks. 
 
Oginme said:
So, just doing a little bit of back of the envelope calculation.  The amount of sugar for carbonation to 1.8 volumes if added to the recipe would give an increase in OG of about 0.001 points.  So, if your gravity at bottling is around 1.023, add a point for the sugar you just out in and you get 1.024.  You are now reading 1.020 so that is a difference of .004 points.  This would give a carbonation rate of about 4.4 volumes equivalent of sugar added. 


Kinda getting into bottle bomb range for standard long necks.

Yeah any more and you don't want to be around I've never blown a bottle but I've had some where the cap goes flying like a  bullet when I open them :(
 
Oginme said:
Perhaps the yeast is stalling out and the addition of a little oxygen and simple sugars is causing a refermentation strong enough to reach a lower gravity.  This could explain why you are not picking up any off-flavors. 

Paul_G, if you're not seeing powdery yeast in the bottle, I think Oginme has identified the key.

A drop of 1.003 is equivalent to dextrose for 2.75 volumes. Along with the intended 1.8, the result would be gushers without off flavors, save maybe acetaldehyde. A wild yeast contamination would usually be accompanied by phenolic (peppery to plastic) flavors.

This would make me look back at my hot break separation, pitching rate, wort oxygenation and fermentation temperature.

Going back further, I'd be looking at my mash pH and post boil pH. Beer yeast will lower pH if the wort starts too high (above 4.5 for most strains), but the earlier generations use up a lot of nutrients in the process. This can stall the last bit of attenuation, which is then restarted by the introduction of oxygen at bottling. The fact that over carbonation happens a few weeks after normal carbonation only reaffirms this hypothesis, for me.

 
brewfun said:
Oginme said:
Perhaps the yeast is stalling out and the addition of a little oxygen and simple sugars is causing a refermentation strong enough to reach a lower gravity.  This could explain why you are not picking up any off-flavors. 

Paul_G, if you're not seeing powdery yeast in the bottle, I think Oginme has identified the key.

A drop of 1.003 is equivalent to dextrose for 2.75 volumes. Along with the intended 1.8, the result would be gushers without off flavors, save maybe acetaldehyde. A wild yeast contamination would usually be accompanied by phenolic (peppery to plastic) flavors.

This would make me look back at my hot break separation, pitching rate, wort oxygenation and fermentation temperature.

Going back further, I'd be looking at my mash pH and post boil pH. Beer yeast will lower pH if the wort starts too high (above 4.5 for most strains), but the earlier generations use up a lot of nutrients in the process. This can stall the last bit of attenuation, which is then restarted by the introduction of oxygen at bottling. The fact that over carbonation happens a few weeks after normal carbonation only reaffirms this hypothesis, for me.

I have to say you my friend are a wealth of ideas and knowledge. I didn't consider that when I was thinking how to help him.

I guess I'm too impatient bleh.
 
Thanks for all the thoughts which gives me some areas to look into.  It does look to me like the fermentation is stalling for darker beers and that I need to look into this further.  I've normally pitched White Labs yeast straight into the fermenter unless its a high gravity beer in which case I've used a starter.  I plan on using a starter going forward.  Better aeration of the wort is another area that I'll look into improving.  I'll also try adding yeast nutrients.  These things will be beneficial to my paler beer too.

I had been wondering if it could be related to pH as that's the big difference between pale and dark beers due to the malts.  I've invested in a pH meter will look a bit further into what is happening with the pH.
 
Greetings Paul_G - your situation is quite perplexing indeed.  I can only offer two more suggestions following the great advise offered by our fellow brewers.  First, my suggestion is to avoid using a refractometer when testing your beer after fermentation begins.  Perhaps I?m ?old school?, but I think you will get much better results using a hydrometer.

Second, I think my fellow brewers might be on to something with their suggestions and ideas.  So, perhaps you would consider brewing a small batch of dark beer to test the theories that have been floated.  Then, I suggest covering your bottles to avoid any possible bodily harm from bottle bombs.  You can go a step farther by only adding priming sugar to half the batch and bottle the other half without priming sugar to see how they compare.  The benefit here is you can test theories without spending a bunch of cash and without wasting beer.

Good luck!
 
Paul_G said:
Thanks for all the thoughts which gives me some areas to look into.  It does look to me like the fermentation is stalling for darker beers and that I need to look into this further.  I've normally pitched White Labs yeast straight into the fermenter unless its a high gravity beer in which case I've used a starter.  I plan on using a starter going forward.  Better aeration of the wort is another area that I'll look into improving.  I'll also try adding yeast nutrients.  These things will be beneficial to my paler beer too.

I had been wondering if it could be related to pH as that's the big difference between pale and dark beers due to the malts.  I've invested in a pH meter will look a bit further into what is happening with the pH.

Paul,

I haven't looked to see if you stated your typical batch size or not, but in brewing 10 liter batches, I find that a single packet of liquid yeast (Wyeast or White Labs) has rarely the cell counts to cover anything over a 1.050 gravity batch when the yeast is fresh (within a couple of weeks of manufacture).  Nearly double that volume for a 5 gallon batch and you are looking at pitching only half of the recommended number of yeast cells.  While you will get fermentation from a single packet, you also leave yourself open to stalling and incomplete fermentation if the rest of the conditions (adequate Oxygen, Zinc, Calcium, etc.) are not present.

A couple of years ago, I wondered why some of my repitches were not performing so well.  In doing some microscopy and staining the cells, it appeared that I was not giving enough of the above (especially dissolved O2) to allow the yeasts to build substantial cells walls.  Harvested yeast cells were thin walled and easily defined as weak through staining.  So, I started being more precise with my starters and pitching based upon cell counts from starters instead of single packets or estimated volume of harvested yeast. 

Another thing that helped me immensely was doing a 'forced fermentation', where I would save out a 200 ml to 300 ml of extra wort from my batch and dump in a boatload of extra yeast I was pitching.  Fermentation would be complete in a couple of days on the counter (covered, but not sealed or air-locked) and I would know what the best possible final gravity for that wort would be.  [note: resultant beer from the forced fermentation was ghastly awful, but the yeast was pretty healthy]  Once I got a handle on that lever and the time it took for the rest of the batch to reach that level, life became much less worrisome around the fermentation aspect of my brewing.

I also totally agree with KellerBrauer about using a hydrometer for your fermented beer.  While I may use my refractometer to track the progress of fermentation of a new yeast strain I am trying, I will always, always, always use my hydrometer for the final gravity measurements.  It is just too important to depend upon only a couple of drops out of a full batch.  [note: even when brewing, I always take at least three readings with my refractometer to confirm a gravity measurement]. While calculators exist for compensating for the presence of alcohol in your refractometer reading, that is also open to errors in calibration and sample size.

As to why your paler beers don't seem to have this issue, I really cannot help you there.  Maybe sorting and looking at them with respect to OG and yeast strains may help give you some insight there.
 
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