Preventing fermentation after forced carbonation

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Kayvon

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The Question
How do I prevent fermentation from occurring in 2-liter bottles of force-carbonated soda?

The Problem
I've force-carbonated many bottles of 2-liter soda on multiple occasions. The bottles are chilled prior to carbonation, but left on the counter afterwards to save space in the fridge. On a couple different occasions, I opened a 2-liter only to have the contents foam immediately out, leaving a mostly-empty bottle. The first such incident was a mango-lime soda. The other was a ginger ale. Both had been made with syrups that were boiled prior to use. Oddly, I have not had any problems with my root beers or cream sodas, even after a week or two without refrigeration.

The Theory
So, I've got a couple guesses here. One is that the bottles themselves need to be cleaned again immediately prior to use with hot, hot water. The other is that the offending sodas both contained citric acid, which would invert the sugar and might leave it more susceptible to fermenting. Oddly, the cream sodas contains a lot of lemon juice but hasn't had that problem. (Come to think of it, the citric acid was added after the syrups were boiled and cooled, so that may be another possible source of bacteria.)

Less likely, there may be some latent yeast in the bottles from when I used yeast-based carbonation. I cleaned all the bottles with blazing hot water after the first incident, which should have killed any yeast, so this seems unlikely. I no longer use yeast as I prefer the forced carbonation flavor.

The Question, Revisited
Are there some steps I can take to prevent unrefrigerated sodas from fermenting?
 
I have never done any soda but unless you have sugars and yeast you have no fermentation. Sodas that foam over IMO are just over carbonated. But, I guess it could be a wild yeast. In that case I would suspect inadequate sanitation.
 
I have never done any soda but unless you have sugars and yeast you have no fermentation. Sodas that foam over IMO are just over carbonated. But, I guess it could be a wild yeast. In that case I would suspect inadequate sanitation.

Ya, true dat. There is no reason why you should have fermentation at all on a force carbed soda. Are you familiar with CO2 absorption rates and temps necessary to do so? Sounds like you know your stuff I am just askin....
 
The bottles need to be sanitized before using. That will buy you a little time.

But just like you don't leave homemade spaghetti sauce on the counter for days and days, you don't want to leave homemade soda on the counter either. A soda, made at home, even if forced carbed, will spoil just as any food product will.

If you must store at room temperature, I'd either make less or find a way to pasteurize after bottling.
 
Are you familiar with CO2 absorption rates and temps necessary to do so? Sounds like you know your stuff I am just askin....

Yes, I should have clarified. The carbonation process works beautifully and tastes great when initially bottled. The problem isn't that everything fizzes out, it's that the flavor is incredibly bad. The wife walked in the kitchen and immediately asked what had fermented. It's similar to when you've left orange juice in the fridge for far too long.

But just like you don't leave homemade spaghetti sauce on the counter for days and days, you don't want to leave homemade soda on the counter either.

That's too bad. I'm using dry ice to make the soda, which must be purchased in blocks, so I can't conveniently make little amounts all the time. It'd be great to find a way to preserve these for a couple weeks without refrigeration.
 
That's too bad. I'm using dry ice to make the soda, which must be purchased in blocks, so I can't conveniently make little amounts all the time. It'd be great to find a way to preserve these for a couple weeks without refrigeration.

If you could find a way to heat pasteurize, that would be the only way I can think of.

Just like any food, unless you've a pressure canner to home can food, keeping it at room temperature allows wild yeast, bacteria, and mold to take hold. Things like botulism are no joke.
 
We have canning equipment that could easily fit 2-liter-size bottles. The question is how much pressure would build up in the bottles during the process.

I may be able to experiment with a regulator cap to approximate safe temperature for pasteurizing. The cider side of the forums are showing 160-190 degrees F for pasteurization efficacy. It's a matter of seeing whether the PET bottles can support that.
 
I almost guarantee you are picking up dormant strains of bacteria and yeast from the dry ice, so it doesn't really matter how well you sanitize the bottles. Once the little critters are exposed to the warm, sugary, moist environment of the soda on the counter, they begin to multiply and take over (sorry, I tried to come up with some sort of colorful metaphor, but alas, my creativity has gone on vacation...). Anyway, the only way to prevent reanimation and expansion is going to be to pasteurize the bottles after they have been carbonated.

As far as pasteurization of a bottle under pressure is concerned, the best way to do so would be a low heat - long time method. Put the bottles in a warm water bath and maintain an internal temp of 145 degrees f for 30 minutes and you should be all set (with no gysers (or however you spell that...)). Just be sure you give the contents of the bottles time to heat to 145 before you start the 30 minutes.
 
Good info, Dutchman. I hadn't even considered the dry ice itself.

I'll try the low-temp pasteurization on a few bottles next time I make some soda. Thanks for all the feedback, everyone.
 
Good info, Dutchman. I hadn't even considered the dry ice itself.

I'll try the low-temp pasteurization on a few bottles next time I make some soda. Thanks for all the feedback, everyone.

If you are force carbing, why not batch pasteurize instead? To help keep wild yeasts and bacteria at bay consider stabilizing with potassium metabisulphite. I make shelf stable simple syrups frequently stabilized with k-meta, batch pasteurized, and no bottle fermentation occurs over the few weeks that bottle is parked on the counter.
 
Thanks for the suggestion.

Never even heard of potassium metabisulphite before today. I'll consider picking some up if the low-temp pasteurization doesn't work. I don't want to batch pasteurize (pre-carbonation) in case the dry ice itself is providing the bacteria, as seems to be the case.
 
I have been wondering this same thing. I haven't tried bottling soda yet, but plan to. Pasteurizing in used PET bottles sounds scary to me. Has anyone who suggested it actually done it? I would worry about bottles exploding.

I was looking toward sodium benzoate. I imagined that many of you are making your own soda to avoid this and other chemicals, but I was hoping someone had tried it and could weigh in.
 
I have been wondering this same thing. I haven't tried bottling soda yet, but plan to. Pasteurizing in used PET bottles sounds scary to me. Has anyone who suggested it actually done it? I would worry about bottles exploding.

I was looking toward sodium benzoate. I imagined that many of you are making your own soda to avoid this and other chemicals, but I was hoping someone had tried it and could weigh in.

Just remember that while benzoate creates an environment that is unfriendly for yeast fermentation you should also consider stabilizing with k-meta since it is an antibacterial/antioxidant. Personally I shudder at the use of benzoate, have you read the MSDS? Instead of benzoate you could use potassium sorbate, it does the same thing. Where sorbate goes k-meta needs to go, as sorbate performs better in the presence of SO2. But remember benzoate and sorbate cannot be used if you plan to bottle ferment, but are fine for force carbonation.

What is your process for making the soda base? If using yeast I would use k-meta, pasteurization, chill, then filter/rack off any sediment & then force carb. If using a yeast-free syrup base, I would consider pasteurization but definitely use k-meta.
 
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