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-   -   Carbonation Variation Between 'Plain' Sugar and Fruit Juice at Bottling (http://www.homebrewtalk.com/f167/carbonation-variation-between-plain-sugar-fruit-juice-bottling-341145/)

othellomcbane 07-12-2012 09:39 PM

Carbonation Variation Between 'Plain' Sugar and Fruit Juice at Bottling
 
I've been making kombucha for about four months now, and I've been bottling it ever since I started. I use 500 ml PET plastic beer bottles with screw-caps from Northern Brewer — no worry about bottle bombs. And I admit, I am not super scientific about when I bottle; I don't take gravity readings. Now that my SCOBY is grown, I generally bottle after 10 - 14 days.

When bottling, I've been experimenting with adding either plain ol' regular sugar and different fruit juices / syrups. And this has led to an odd (to me) and unexpected realization: my kombucha never carbonates when bottled with plain sugar. Maybe a tiny trace amount of fix that might as well be leftover from the initial fermentation. I have added between 1 and 2 tablespoons of sugar to each 500 ml bottle, and something definitely consumes the sugar, because the kombucha with 2 tablespoons never tastes sweeter, as it should if the sugar was just sitting in there.

However, when I bottle with fruit juice or syrup—regardless of how much I add—I always get good carbonation. 2 tablespoons or more and I get intense carbonation; more so the longer I let the kombucha sit.

So, my guess is that the plain sugar, being a simple sugar, succumbs to the non-CO2 forming bacteria before the yeast can get to it. The fruit juice/syrup, containing more complex sugars, requires a longer fermentation and gives the yeast more chance to create CO2. Or something like that. But I'm not kombucha expert, and I'm hoping someone here can shed more light on this curiosity.

Also, I will add that my kombucha has been coming out shockingly well so far; better than my expecations. Even un-carbonated, I prefer it to the majority of the store-bought kombucha I've had.

Zapped 07-12-2012 10:59 PM

Interesting observation. I've always added about 3oz of fruit juice per quart/liter for secondary (sealed/anaerobic) fermentation and also had good carbonation, but I've never tried using straight white sugar.

I'm not trying to nitpick & I'm no expert here, but what do you mean by "complex sugars"? My understanding is that standard sucrose (table sugar) is 50% fructose & 50% glucose, connected by an easy-to-break bond. Fruit juices typically contain free fructose (not bonded to glucose) as well as glucose and also sucrose. I've only heard "complex" used to distinguish carbohydrates, but not with respect to sugars - all of which I'd consider "simple".

onipar 07-13-2012 02:23 AM

I haven't used table sugar for bottling, but pretty much everything else I've used has worked well (fruit juice, cherries, blueberries, ginger...) It's definitely a different kind of carbonation than beer, but I even get a bit of head with the fruit at bottling.

Not sure why white sugar wouldn't work as well, but I have more fun using natural flavorings to boost carbonation anyway.

Plain Kombucha (no additions) definitely doesn't carb up as well or as quick. :mug:

othellomcbane 07-13-2012 01:11 PM

Quote:

Originally Posted by Zapped (Post 4247132)
Interesting observation. I've always added about 3oz of fruit juice per quart/liter for secondary (sealed/anaerobic) fermentation and also had good carbonation, but I've never tried using straight white sugar.

I'm not trying to nitpick & I'm no expert here, but what do you mean by "complex sugars"? My understanding is that standard sucrose (table sugar) is 50% fructose & 50% glucose, connected by an easy-to-break bond. Fruit juices typically contain free fructose (not bonded to glucose) as well as glucose and also sucrose. I've only heard "complex" used to distinguish carbohydrates, but not with respect to sugars - all of which I'd consider "simple".

Good info on the sugars, thanks. I was just carelessly using that term without giving it much thought; I don't have a very good understanding of how sugar works, as you can see. I figured there must be something in the fruit that isn't in the plain sugar, since the plain sugar seems to get devoured much faster.

It seems most people add some kind of fruit almost all the time. I actually like the flavor of "plain" kombucha a lot, almost more than most of the fruit varieties I've tried. I might try bottling with either agave syrup or honey next, to see if those provide carbonation without significantly altering the flavor. Has anyone used either of those at bottling?

onipar 07-13-2012 02:57 PM

Nope, haven't used agave or honey either.

I will say this. When I use just a few blueberries, and even the cherries, it speeds up carbonation and gives it a cool color, but I don't really taste those flavors. So that might be something you'd like.

othellomcbane 07-13-2012 06:10 PM

I will definitely try that. I've been thinking a blueberry (also strawberry) kombucha would both be good, and neither of those comes in a convenient juice form.

Zapped 07-13-2012 07:34 PM

Our local Costco has great prices on a 4lb bag of "mixed berries". Whole organic raspberries, blackberries, and blueberries with no syrup or sugar added. I like to make "mocktails" (non-alcoholic cocktails) with them in my Kombucha. I'll warm up a tablespoon or two in the microwave, smash them up, and add it to my KT. Really tasty.

You'd probably have great luck mashing up some of those thawed berries and using them in your secondary ferment. You could strain them away when you do your final bottling if you don't want all the flotsam & jetsam in the final product.

onipar 07-13-2012 09:03 PM

Quote:

Originally Posted by Zapped (Post 4249377)
Our local Costco has great prices on a 4lb bag of "mixed berries". Whole organic raspberries, blackberries, and blueberries with no syrup or sugar added. I like to make "mocktails" (non-alcoholic cocktails) with them in my Kombucha. I'll warm up a tablespoon or two in the microwave, smash them up, and add it to my KT. Really tasty.

You'd probably have great luck mashing up some of those thawed berries and using them in your secondary ferment. You could strain them away when you do your final bottling if you don't want all the flotsam & jetsam in the final product.

That sounds really good! I've been mostly flavoring my kombucha during bottle priming, but this post priming (in the cup) flavoring sounds like a good idea. I've only tried this in the most basic form (mixing some juice with kombucha), but the mixed berries sounds awesome.

Zapped 08-17-2012 04:09 PM

Just got around to some experiments to compare sugar vs juice in secondary fermentation.

Primary ferment - two identically prepared gallons. Each gallon made from purified water, 3 black tea bags, 3 green tea bags, 1 cup of sugar. Fermented 9 days at room temp, covered with cotton cloth.

Secondary ferment - four days at room temp in six different 1-liter flip-top jars, with six different recipes:
A = Acai juice (3oz, 11g sugar)
C = Pomegranate/Cranberry juice (3oz, 13g sugar)
S = Plain white Sugar (two tspns, 8g sugar)
AG = like A but with some fresh-pressed Ginger added
CG = C + Ginger
SG = S + Ginger

Observations: Acai seemed to carbonate the most, Cran/Pom next, Sugar least. I judge that based on how quickly the liquid tries to leap out of the bottle when I flip the lid to assess it. All of them bubble, then after a second or two the liquid begins to rise. To be clear: ALL combos were very fizzy - I'm just observing that the Acai fizzed the most.

Adding ginger seemed to "hold back" the carbonation a little - when I uncapped them during secondary ferment to check, the ones with Ginger didn't try to rise out of the bottle as quickly as the combos without Ginger.

I didn't calculate the grams of sugar before writing this up, so now I wished I tried to keep the grams of sugar constant. Next time I should try 3 tspns sugar (12g) or even 4 tspns sugar (16g) in a 1-liter bottle - although I do miss the added taste of the fruit in the final product so I'm not sure I'll make myself do the experiment.


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