Bottle bombs everywhere and not a drop to drink

[MKane94513]

I could use some learned advice from the forum. Just finished pasteurizing my 4th cider batch and netted only 9 bottles out of 35. I am at a loss as to what I am doing wrong.

To set the stage - I fermented a batch of Apple Cherry cider using turbonado sugar, champaign yeast, pectin enzyme and yeast nutrient. Started with a specific gravity of 1.055 and ten days later ended up with a SG of 1.001. Figured that to be 6.5 - 7% ABV. All good to that point. Netted about 4 gals of nice clean cider.

Moved to a bottling bucket and added 1 can frozen apple juice concentrate, 2 cups pasteurized cherry juice for flavor and 1.25 cups white sugar. Bottled the cider in used (3rd time) Groelsch flip top bottles using replacement seals. Last time around I noticed that the factory seals blew out on a couple of bottles and I had some fizzing on others so I changed up for these:

Mentioning it because these are really good seals and that may have increased bottle pressure.

6 days later my plastic tester bottle was rock hard. Popped the cap on a flip top and it was normally carbonated, a bit sweet but pretty good.

I set up my sous vide station in the kitchen at 165 degrees and dropped in the first 5 bottles. As soon as they hit about 140 degrees two of them went off like hand grenades. Full stop to rethink.

I assumed that thermal shock was the culprit so I set up a large cooler in the back yard and loaded all of the bottle in with cold water about to the top of the bottles. Let the temp equalize and set the sous vide heater in with a target temp of 140. Plan was to slowly take them up to temp. It took about an hour to get the bath up to 135.

It was like The Sands Of Iwo Jima in my back yard. Bottles continued to detonate even after i cut power to the heater for about an hour.

The surviving bottles were not overly sweet or over carbonated so why did I have so many bottle bombs?

I am at a complete loss as to what I did wrong.

 

[Dinadan]

Seems to me that you added a lot of stuff in the bottling bucket. When I bottle a five gallon batch, I add one cup of sugar for bottling. Period. I have never had a bottle bomb. So you added just a bit more sugar than I use for five gallons, and also added the apple concentrate, probably 12 oz, and also two cups cherry juice. Clearly, that is too much to add.

I suggest you try to figure out just how much sugar content is in the apple juice and cherry juice, and make sure the total sugar added to the bottling bucket is not more than one cup.

 

[MKane94513]

Can't disagree with your logic. Thanks for the info,

What I don't understand though is why the surviving bottle are normally carbonated. You would think that they would be gushers if there was that much pressure in the flip tops. Since I did not take a specific gravity reading after adding the sugar I do not know where the sugar levels were. Will do next time around - all part of the fun I guess.

Cheers

 

[dmtaylor]

Moved to a bottling bucket and added 1 can frozen apple juice concentrate, 2 cups pasteurized cherry juice for flavor and 1.25 cups white sugar. Bottled the cider ...

6 days later my plastic tester bottle was rock hard.

That ****'s all fermentable, and your fermentation was nowhere near finished at 1.001 when you added it and bottled. You probably had full carbonation not in 6 days but in 1-2 days. I'm shocked that you got any bottles not to explode. The only reason they survived was probably due to leaky seals on those particular bottles.

If you are going to bottle, in future, I would give the cider not just 10 days to finish but closer to 10 weeks. Or okay, let's say at least 5 or 6 weeks. Then to bottle and backsweeten, instead of adding all that extra stuff (well you could add it at beginning of fermentation but then) when bottling, just use priming sugar and xylitol for sweetening. Xylitol tastes like sugar but won't ferment. Then you can enjoy standard carbonation after a few weeks, instead of risking gushers or bombs after just a couple days, and no need to sous vide.

Overall, my advice is to keep it simple. Less is more.

P.S. Welcome to the forum and the hobby!

 

[Dinadan]

Good point about the bottles that were normal. I use a lot of Grolsh type bottles myself. I have noticed that occasionally I get a bottle that is not carbonated much, if any. Something about the gaskets, I guess. Maybe your surviving bottles are the ones that did not seal very well?

 

[MKane94513]

Thanks all - I will say that the replacement seals really work well if you are reusing the flip bottles. I will back 'way off of the sugar next time.

Great thing about this hobby - even the failed attempts taste pretty good!

 

[Chalkyt]

Maybe you should sell your recipe to the military! Sorry, as dmtaylor suggested the amount of fermentable sugars that you added makes a great recipe for bottle bombs.

My take on the situation is that you primed for bottling and carbonation by adding around 550 or so grams of sugar. These are rough sums so please suffer the long winded explanation, but I would guess...

1 cup of AJC (based on our local brands) would be about 250g
1.25 cups of sugar would be about 250g
2 cups of cherry juice might be in the order of 50g

So altogether in something like 15 litres (sorry, I work in metric... it is easier), the concentration would be something like 30 grams per litre giving you a bottling SG of around 1.012. Once again the arithmetic is a bit rough but it will give you an idea if what might have happened.

Even though the SG of 1.001 at the end of your primary fermentation suggests that it was approaching "finished", the yeast were still active but just running out of sugar to eat. The new sugar was the start of another feeding frenzy!

Since your primary fermentation went quite quickly from 1.055 to 1.001 in ten days, it is likely that the bottled cider at 1.012 also "finished" close to 1.000 over the six days. So, fully fermented (by the residual yeast), your bottles might have developed around 5 or 6 volumes of CO2. The "rule of thumb" is that a SG drop of 0.001 will generate 0.5 volumes of CO2. So even taking a conservative approach, according to Henry's Law 5 atmospheres or volumes of CO2 driven out of solution at 60C (140F) would generate 207 psi, and at 74C (164F) this would be 288psi.

No wonder things went BOOM!

At typical cider carbonation levels of say 2.5 atm and a normal pasteurisation temperature of 65C (149F) the bottle pressure would reach just over 100psi which is about as far as you would want to go, even with Grolsch bottles. I must say that I have also found leaky seals at this sort of pressure so the surviving bottles probably had a "built in safety valve".

The possibly leaking seals may have limited the pressure in the surviving bottles to around 100psi (just a guess) at pasteurisation temperature. As the bottles cool own, the internal pressure returns to normal (something like 2 or 2.5 atm) as the CO2 goes back into solution so they would not have appeared overcarbonated at room temperature.

Let the journey continue... good luck, I hope this helped!

 

[moorejl57]

Sorry to hear about the bottle bombs, I too use ez cap 500 ml bottles. Thankfully you learned a difficult lesson without getting injured. I was also just looking at those particular replacement seals on Amazon, so thanks for the feedback. My last mini batch of SMaSH ale had about 25% leaking bottles (could see tiny bubbles rising in the bottles during carbonation) with low carbonation with the remainder at about 2.5 volumes. I used 3 grams of sucrose per bottle administered as a syrup with a syringe. This is a very flexible way to prime and you can use a range of syrup volume to see where you get the best level for your taste. Rather than go the in bottle pasteurization route, you could ferment out completely dry, bottle with a reasonable amount of sugar to carbonate and back sweeten in the cup at serving time with a simple syrup or some thawed apple concentrate.

 

[Redeemer]

Many of us have been there and champagne yeast (Especially EC1118) is an utter beast. I ran into this issue with a grape soda I made a few months ago, and this was after opening all the bottles after 3 days to relieve pressure. I have nobody but myself and my own hubris to blame but yeah, it wasn't pleasant. I lost about 15 bottles of a 6 gallon batch.

 

[JAReeves]

When we do ciders (mostly apple), we tend to use some form of juice as the priming sugar. We have used Pear, Apple, PassionFruit, and Cranberry (straight juice or concentrate). Watch out for preservatives, like sorbate unless you want to stun the yeast.

Our ciders ferment out dry first, and then the sugars in the juice become the sugars for carbonation; they still carbonate out dry. I use the calculators on Brewer's Friend to estimate sugar needed for ~2.5.

The one time we made a sweeter cider (a Perry), we let it ferment dry. Then we added sorbate and K-Meta to make sure the yeast were stunned. After a day, we added in pear juice to taste and then kegged it for carbonation.

The apple ciders are usually wild yeast fermented. The others we've use an ale yeast or a white wine yeast (sometimes using a beer's leftover yeast cake).

Not sure if this helps or not.

 

[Ronnb]

If you are going to bottle, in future, I would give the cider not just 10 days to finish but closer to 10 weeks. Or okay, let's say at least 5 or 6 weeks. Then to bottle and backsweeten, instead of adding all that extra stuff (well you could add it at beginning of fermentation but then) when bottling, just use priming sugar and xylitol for sweetening. Xylitol tastes like sugar but won't ferment. Then you can enjoy standard carbonation after a few weeks, instead of risking gushers or bombs after just a couple days, and no need to sous vide.

Overall, my advice is to keep it simple. Less is more.

I concur. I would let it sit for at least a month.