extreme bottle bombs

[A-Juice]

I am having a problem with bottle bombs that I need help resolving.

I have been homebrewing for about a year and a half with about 10 extract brews and then 5 BIAB brews under my belt. My results have been mostly positive with only one awful batch and one more that I didnt like. the other 13 batches have been very good to excellent. I rotate the brews on an ale-porter-stout schedule so my experience includes about 5 of each.

So the batch in question is a pumpkin bread porter which i found in the beersmith database. I missed the target OG of 1.080 with a measured OG of 1.064. I suspect that the LHBS is not double crushing my grains as requested but that is not the issue at hand. I left it in primary fermentation for 27 days.

My normal process is 3 weeks in primary and then into the bottles. I normally take a hydrometer reading on bottling day, but normally do not take readings in the days leading up to bottling day to check for completed fermentation. i control the temp in a swamp cooler between 66 and 72 degrees.

So back to my pumpkin porter...by the 27th day in primary, i was itching to bottle and it never crossed my mind that fermentation might not be completed. I measured the gravity on bottling day at 1.016 which was 2 points higher than the target of 1.014. i used 5 oz of priming corn sugar dissolved into boiling water and then cooled. I racked the beer over half the primer and added the other half of the primer when the bottling bucket was half full. i stirred gently for uniform distribution of the sugar but without aerating.

I noticed the first bottle bomb on tuesday which was 10 days after bottling. since that time, I have lost maybe 6 to 8 more. I have the bottles in my attached but unconditioned garage with an ambient temp around 80 to 85 or so. I have had a couple bottle bombs before but nothing like this. i have since moved the bottles into a cooler to contain future explosions.

I decided to open a couple of the beers to attempt an investigation. When opened, the beer fizzed strong and then gushed foam. I think I opened three with identical results. I tasted it and it was warm, nasty and sour tasting. not at all like how it tasted on bottling day. I captured some of the beer and let the foam die off and measured the gravity at 1.09. I moved one bottle to the refrigerator and plan to open it after chilled a couple days to make observations.

so i have the following theories.

1. Overcarbontaion. This seems unlikely to me. i am notorious for undercarbonation and didnt do anything unususal here.

2. Conditioning temp too high. Again, i havent done anything different than my normal routine here. I have other beers bottle conditioning on the same shelf with no issues. seems unlikely as the sole cause although it could be a contributing factor.

3. infection during bottling. I have never had an infection before. my sanitary methods are not meticulous but have always been adequate. i clean and rinse my equipment after using and then before using again. i sanitize with star san. i keep the bottles clean with oxyclean and they do through the dishwasher on bottling day. I think it COULD be an infection but am not convinced that it IS an infection.

4. incomplete fermentation. My gravity reading of the bottled beer seems to indicate that fermentation is continuing in the bottle. Perhaps the sour taste is because the fermentation gasses have no escape route through the bottle caps. This seems like the most likely cause to me at this point.

So here is what I need for help...

What do you think the cause of the bottle bombs is and what do you think i should do about it?

Thanks.

 

[Mozart]

Overcarbonation: If you measured your priming sugar and mixed thoroughly, per your usual process, which you state you did, this likely isn't the cause.

Conditioning Temp: The yeast can produce only as much CO2 as the available sugars allow them to regardless of the temperature.

Infection: Possible. In absence of any off flavors or any other indication of an infection, I'd say it isn't the most likely cause.

Edit: I didn't catch the 'sour and nasty' taste the first time I read your post. I agree with those that followed that this is a pretty strong indicator of infection.

Incomplete fermentation: This one gets my vote. I know your measured OG was 1.064, but if your recipe was 1.080 is it possilbe that the wort wasn't mixed thoroughly when you took your OG reading? If it wasn't, your actual OG could have been closer to the recipe OG than you realized. The difference between 1.080 and 1.064 is a pretty big one. A 1.080 beer can take a while to ferment out completely.

Were that my batch of beer, I'd chill them down and sacrifice (i.e. dump) the batch. Others might try to release some pressure and recap, so to each his or her own, but someone actually getting hurt by a bottle bomb is something that I just personally wouldn't risk.

 

[duboman]

IF you have had bottle bombs in the past then you need to evaluate your process from verifying FG to weighing out your priming sugar based upon the final volume of beer to be bottled as something is going on. You taste of sour leads me to believe the beer is infected because unless you intended this to be a sour, sour means infected and this could be from the pumpkin or from poor sanitation process, hard to determine.

Priming bottles is a pretty exact science: You take a finished volume of fully fermented beer, add a specific measurement of priming sugar, residual yeast ferment this exact measure of sugar to produce a specific level of CO2 in the bottle.

Bottle bombs occur because:
1. Beer did not fully ferment
2. Too much priming sugar was used
3. Infection

If you are measuring your sugar by volume you need to begin measuring by weight-it is just more precise
If you are not verifying FG by stable readings you need to start
If you are assuming you are bottling a full 5 gallons when in reality you are not then you need to measure better
If you are not sanitizing using Star-San or Iodophor from caps to bottles to bucket to spigot to racking cane and tubing, etc you need to start

A good rule of thumb is 3/4-1 oz per finished gallon of beer or 21-28 grams per finished gallon and this will depend on the style of beer you are carbonating but like I said, sour to me means infected

 

[LLBeanJ]

I also think you can rule out overcarbonation. Conditioning temps in and of themselves wouldn't be an issue unless the beer wasn't actually done fermenting, in which case the warmer temps, along with a fresh dose of priming sugar would jumpstart fermentation. Given that it was such a big beer, it could very well be this.

I tasted it and it was warm, nasty and sour tasting. not at all like how it tasted on bottling day. I captured some of the beer and let the foam die off and measured the gravity at 1.09.

1.09? Do you mean 1.009? If so, to go from 1.016 to 1.009 in the bottle sounds like some definite ordinance in the making. If it was supposed to finish at 1.014 and was at 1.009 at time of detonation, I'd be thinking infection as the most likely culprit, especially given that the taste was noticeably off.

 

[duboman]

Just thought of one other question-Are you measuring your FG with a refractometer or hydrometer? If the former you need to use the latter as once alcohol is present refractometers are not reliable in measuring FG as far as I'm concerned.

 

[A-Juice]

thanks for the input so far. A couple clarifications...

I am measuring gravity with hydrometer and then correcting for temperature with beersmith.

The SG in the bottle is 1.009 and not 1.09.

I did come up short on my volume at bottling time due to the heavy pumpkin trub. My bottle volume was 4.5 gallons. My corn sugar was 5 oz by weight. So probably a little strong, but I still doubt overcarbonation is the culprit here.

The pumpkin was from a can and went in the boil. Also, there were no signs of infection at bottling time when I tasted it. Accordingly, I had that ruled out as a source of infection. I could still have been infected in the bottling bucket, or the transfer hoses. If it were only a few of the bottles, it seems like only those bottles would have trouble and not the entire batch which seems to be the possible case.

I plan to open the chilled bottle tomorrow and inspect it. Measure gravity and taste. Meanwhile, the remaining bottles are under quarantine.

Thanks for the help and keep it coming if anyone has any other ideas or suggestions.

 

[duboman]

Not sure what the beer temperature was but 5oz of sugar into 4.5 gallons of beer puts you close to 3 vols of CO2 which is kind of high for a standard beer bottle. Just sayin, most people shoot for 2.3-2.5. Could be weak bottles if nothing else stands out.

 

[A-Juice]

well i opened the chilled one today. It was still a gusher but mush more subdued. Still tasted nasty but cold.

I am leaning toward incomplete fermentation over infection at this point but it could be either. I peeked into the quarantine area today and there is major carnage. Before too long, I think all of the bottles will have exploded.

 

[divrguy]

Not sure what the beer temperature was but 5oz of sugar into 4.5 gallons of beer puts you close to 3 vols of CO2 which is kind of high for a standard beer bottle. Just sayin, most people shoot for 2.3-2.5. Could be weak bottles if nothing else stands out.

Yeah that's a lot of sugar for 4.5 gallons plus if you think you had incomplete ferment and a possible infection, holy cow get rid of those missiles!

 

[454k30]

I'm going to say infection as well. You can over carb by quite a bit without blowing bottles. Those little nasties are far more gassy.