Long Term Storage Of Fruit Soda's

Never made a soda before, but ive got about 20 lbs of blackberries and am considering boiling to syrup, adding sugar + water, kegging, force carbing, then transferring to bottles for storage. It would be nice if these bottles would keep for at least a whole year, preferably without refrigeration.

Im assuming some sort of preservation technique such as pasteurizing and/or adding a preservative may be necessary. along with strict sanitation of course..

Can anyone enlighten me on the possibilities here?

Pasteurize and you should be fine. I don't think you'd have any problems keeping them 6 months or so. Longer and the flavor may fade. Best way to know for sure is to try it.

Thank you MrFoodScientist

You're likely going to want to add some sort of acid to drop the pH down below 3 or so. Pretty much all commercial fruit sodas contain citric acid, which you can get at your LHBS or health food store (it's used frequently in canning). If you'd rather avoid measuring out powdered citric acid, you can add in lemon or lime juice instead, although that will obviously have more of an impact on the flavor profile of the soda.

Either method should also help the flavor, as force carbed soda usually gets cloyingly sweet without some sort of added acidifier (as in, a source of acid other than carbonic acid from the CO2).

TheFizzologist said:

to drop the pH down below 3 or so.

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In order to prevent bacterial contamination such as Botulism? or what is the principal purpose of below 3 pH?

C. botulinum is prevented at anything below 4.6, which you should be there with carbonic acid (carbonated water) already. Yeast and mold can grow below that, though. While a pH of 3 is a good idea, yeasts and mold should be taken care of with the pasteurization. So I don't think it's necessary for preservation, but I do agree that it certainly won't hurt and it will help the flavor tremendously.

If you taste IZZE fruit drinks, which are marketed as sparkling juice, you'll notice that they are way more tart than typical soda. It gives it a more fruity, fresh taste, even if the sugar level is similar to a can of coke.

I'm new to soda, So I can add citric acid or pasteurizing the soda for longer shelf life. How much citric acid do I need in 5 gal keg?
I would like to know how to pasteurize the soda? I make my soda from fresh fruits.

MrFoodScientist said:

C. botulinum is prevented at anything below 4.6, which you should be there with carbonic acid (carbonated water) already. Yeast and mold can grow below that, though. While a pH of 3 is a good idea, yeasts and mold should be taken care of with the pasteurization. So I don't think it's necessary for preservation, but I do agree that it certainly won't hurt and it will help the flavor tremendously.

If you taste IZZE fruit drinks, which are marketed as sparkling juice, you'll notice that they are way more tart than typical soda. It gives it a more fruity, fresh taste, even if the sugar level is similar to a can of coke.

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I love the IZZE drinks! I've never made soda, but would love to do some of those.

Brewnanza said:

I'm new to soda, So I can add citric acid or pasteurizing the soda for longer shelf life. How much citric acid do I need in 5 gal keg?
I would like to know how to pasteurize the soda? I make my soda from fresh fruits.

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I think it's along the lines of how you would can your own jam. just boil for the proscribed period of time. No need for pressure cooking like meats and less acidic foods.

Haven't done it yet, so seek a second opinion.

I make soft-drinks over here in Blighty, on a very small scale. We pasteurise every product via hot-water bath.

Basically take a big enough saucepan to be able to cover 90% of the bottle with water. Put something in the bottom of the 'pan - a cooling rack or similar works best. You need this to stop direct heat being applied to the bottles as this will cause them to explode more often and this is VERY dangerous. Literally a grenade at that point.

Heat the water to 72 Centigrade, keep it at that temperature and make sure it doesn't dip below and keep it there for 20 minutes. This works for up to 750ml bottles.

You cannot do this with PET plastic bottles as the resin in the plastic will leach in to the product. The one exception to this is if the bottles are 'hot fill', but you cannot know this unless you're buying them new, so as a rule don't pasteurise in plastic. Ever.

This should give you a 24 month shelf life as long as you keep them out of direct sunlight, heat or other oxidising factors.

Hope this helps!