Measuring ABV in champagne booch

[Marea]

New member, 1st time posting.
I have been making hard kombucha (champagne booch) for several months now. I'm in the process of getting required permits to sell commercially so I need to get the ABV measurement down. I purchased a hydrometer from a home brew shop, only to learn that those are not very accurate measuring tools. I believe a refractometer would be better, correct?

I will be doing a total of 3 ferments (1F=sweet tea+SCOBY, 2F=fermented kombucha+champagne yeast/sugar, 3F=fermented alcohol kombucha+fruit juice) to get to my end product of champagne kombucha, so will I need to measure before and after each ferment?
Also, my airlock bubbles every few minutes - I think that means it is still "active"? Once it stops bubbling does that mean it's ready to be pulled?

 

[RPh_Guy]

Paying a lab to run a gas chromatography (GC) analysis is the only sure way to know the alcohol level.

Both hydrometers and refractometers are very accurate at what they measure -- when properly calibrated. However, neither instrument will be able to determine the alcohol level of kombucha.
Refractometers are not very useful for measuring sugar density in solutions with alcohol.
Neither refractometers nor hydrometers can account for the acetic acid.

Sorry to bear the bad news.

There's possibly a convoluted method to directly measure the alcohol yourself using a narrow-range (0.001 resolution) hydrometer and a quality pH meter ... You can relatively easily measure the acetic acid, but calculating the alcohol will still be tricky and probably unreliable.

Also, my airlock bubbles every few minutes - I think that means it is still "active"? Once it stops bubbling does that mean it's ready to be pulled?

Airlock bubbling is not a reliable indication of fermentation activity.
CO2 is released for a long time after alcoholic fermentation completes, and also any change in pressure (e.g. atmospheric pressure changes or temperature changes) can cause bubbling.
On the other hand a lack of bubbling also is meaningless because there could simply be a leak.

Welcome to HBT!

 

[Vale71]

Paying a lab to run a gas chromatography (GC) analysis is the only sure way to know the alcohol level.

I don't know where you got that information but these have been around for quite a while and they're very accurate. They're not cheap though.

https://www.anton-paar.com/corp-en/...MI0ZDgiu344gIV1jLTCh0EcQdDEAAYASAAEgIrc_D_BwE

 

[RPh_Guy]

I don't know where you got that information but these have been around for quite a while and they're very accurate. They're not cheap though.

https://www.anton-paar.com/corp-en/products/group/alcohol-meter/?ref=adwords&utm_term=alcohol meter&utm_medium=ppc&utm_campaign=HQ_BUM.LDC_EN&utm_source=adwords&hsa_tgt=kwd-297574842903&hsa_ad=292737506066&hsa_net=adwords&hsa_ver=3&hsa_cam=1022032078&hsa_kw=alcohol meter&hsa_acc=8367179031&hsa_mt=b&hsa_src=g&hsa_grp=52723804999&gclid=EAIaIQobChMI0ZDgiu344gIV1jLTCh0EcQdDEAAYASAAEgIrc_D_BwE

You're right. I should has said only possible using $$$$$ equipment, not a $7 hydrometer.

 

[Marea]

Paying a lab to run a gas chromatography (GC) analysis is the only sure way to know the alcohol level.

Both hydrometers and refractometers are very accurate at what they measure -- when properly calibrated. However, neither instrument will be able to determine the alcohol level of kombucha.
Refractometers are not very useful for measuring sugar density in solutions with alcohol.
Neither refractometers nor hydrometers can account for the acetic acid.

Sorry to bear the bad news.

There's possibly a convoluted method to directly measure the alcohol yourself using a narrow-range (0.001 resolution) hydrometer and a quality pH meter ... You can relatively easily measure the acetic acid, but calculating the alcohol will still be tricky and probably unreliable.

Airlock bubbling is not a reliable indication of fermentation activity.
CO2 is released for a long time after alcoholic fermentation completes, and also any change in pressure (e.g. atmospheric pressure changes or temperature changes) can cause bubbling.
On the other hand a lack of bubbling also is meaningless because there could simply be a leak.

Welcome to HBT!

Thank you, I'm excited to be here!

I had spoken with someone at another local home brew place and he said the same thing (needing to pay a lab to test), especially since I will be selling commercially in the future.

 

[Vale71]

The standard method of determining ABV anyway is through distillation, which is somewhat cheaper than using these modern instruments but definitely a lot more time consuming.

 

[Vale71]

I had spoken with someone at another local home brew place and he said the same thing (needing to pay a lab to test), especially since I will be selling commercially in the future.

That mostly depends on your production volume, if it's large enough it might be economical to acquire the necessary tools and measure yourself, otherwise a lab is definitely your best option.

 

[DIYer]

New member, 1st time posting.
I have been making hard kombucha (champagne booch) for several months now.
...
I will be doing a total of 3 ferments (1F=sweet tea+SCOBY, 2F=fermented kombucha+champagne yeast/sugar, 3F=fermented alcohol kombucha+fruit juice) to get to my end product of champagne kombucha.

I can't help with your question, but I wanted to say thanks for introducing me to the concept of champagne kombucha. I made regular booch last year, but never heard about this. Time to start growing a SCOBY again! And if you have any tips you'd like to share for the "champagne" version, I'd love to hear them.

 

[Marea]

I can't help with your question, but I wanted to say thanks for introducing me to the concept of champagne kombucha. I made regular booch last year, but never heard about this. Time to start growing a SCOBY again! And if you have any tips you'd like to share for the "champagne" version, I'd love to hear them.

Sure thing! It's pretty easy. After the 1st ferment is done and you have kombucha, I add 1C sugar, 2tsp champagne yeast (which is the entire packet) and 1 cup water to the booch in a carboy fitted with an airlock lid. Let that ferment for 14ish days, then bottle with juice or fruit.

 

[RPh_Guy]

The standard method of determining ABV anyway is through distillation, which is somewhat cheaper than using these modern instruments but definitely a lot more time consuming.

Do you have insight into the calculations when a significant portion of the ethanol has been metabolized to acetic acid?
The acetic acid will vaporize along with the ethanol and it's a lot more dense.

 

[Vale71]

Do you have insight into the calculations when a significant portion of the ethanol has been metabolized to acetic acid?
The acetic acid will vaporize along with the ethanol and it's a lot more dense.

If the state agency that's levying the alcohol tax is happy with distillation as the standard method then I'm happy too. Now if your goal is to publish some research paper then there are definitely better options but I don't think that's the case with the OP.

 

[RPh_Guy]

Fair point.

It makes sense to go with whatever method the tax agency uses, even if it's wildly inaccurate for kombucha.

 

[Vale71]

Standard methods are just that, standard. They might not be the best as far as absolute accuracy goes but sometimes you just have no choice but to use them.

 

[WaterCurses]

Paying a lab to run a gas chromatography (GC) analysis is the only sure way to know the alcohol level.

Both hydrometers and refractometers are very accurate at what they measure -- when properly calibrated. However, neither instrument will be able to determine the alcohol level of kombucha.
Refractometers are not very useful for measuring sugar density in solutions with alcohol.
Neither refractometers nor hydrometers can account for the acetic acid.

Sorry to bear the bad news.

There's possibly a convoluted method to directly measure the alcohol yourself using a narrow-range (0.001 resolution) hydrometer and a quality pH meter ... You can relatively easily measure the acetic acid, but calculating the alcohol will still be tricky and probably unreliable.

Airlock bubbling is not a reliable indication of fermentation activity.
CO2 is released for a long time after alcoholic fermentation completes, and also any change in pressure (e.g. atmospheric pressure changes or temperature changes) can cause bubbling.
On the other hand a lack of bubbling also is meaningless because there could simply be a leak.

Welcome to HBT!

Hi, I just created this account to ask this haha. I'm trying champagne booch for the first time right now and I bought a cheap refractometer and it seems like it's useless. I'm just brewing for myself so I'm just wanting to know if my brew is closer to %5 or %10, etc. Would a hydrometer return inaccurate/non-precise readings or just completely useless readings altogether? Thanks

 

[RPh_Guy]

The best way to do this (in my opinion) is to make the kombucha as normal. When that's finished, it should have a negligible amount of alcohol if you made it "correctly".

Remove the pellicle and however much liquid you need to save for the next batch.

Then you add enough sugar to reach whatever alcohol level you want, along with your rehydrated wine yeast (and optionally some yeast nutrient). Take a hydrometer reading at that point and then again when fermentation completes. Using those values you can use an ABV calculator to determine a good approximation of the alcohol percentage.

If you just want a rough ballpark estimate without all the measurements, you can just go by the concentration of sugar that you added with the wine yeast. One pound of sugar in one US gallon will yield approximately 5% ABV.

A refractometer is probably not a great tool for this because it adds additional uncertainly.

Welcome to HBT.

 

[WaterCurses]

Thank you very much for the reply, I really appreciate it! So I should probably return my refractometer for a hydrometer and fo from there, then, it seems.

Thanks for the welcome as well.

 

[MChai]

The best way to do this (in my opinion) is to make the kombucha as normal. When that's finished, it should have a negligible amount of alcohol if you made it "correctly".

Remove the pellicle and however much liquid you need to save for the next batch.

Then you add enough sugar to reach whatever alcohol level you want, along with your rehydrated wine yeast (and optionally some yeast nutrient). Take a hydrometer reading at that point and then again when fermentation completes. Using those values you can use an ABV calculator to determine a good approximation of the alcohol percentage.

If you just want a rough ballpark estimate without all the measurements, you can just go by the concentration of sugar that you added with the wine yeast. One pound of sugar in one US gallon will yield approximately 5% ABV.

A refractometer is probably not a great tool for this because it adds additional uncertainly.

Welcome to HBT.

Will this method also work with kombucha beer? I just got some saison and kveik yeasts I want to experiment with. Possibly a silly question (I can't think of why they type of yeast would matter), but I'm also extremely new to brewing, so I thought I'd ask to make sure.

And, what kind of accuracy could I expect with this method? I am not looking to sell my brew, I just want to know whether the ABV is closer to 2% or 6% (or hopefully eventually even higher).

Also: would it not be possible to use the discrepancy between the hydrometer and refractometer readings to estimate the ABV (even without the original gravity reading)?

Many thanks in advance for your input!

 

[RPh_Guy]

Will this method also work with kombucha beer?

Are you thinking about adding wort instead of sugar and using an ale yeast? That's fine, and you can skip the nutrients since wort has plenty.

And, what kind of accuracy could I expect with this method? I am not looking to sell my brew, I just want to know whether the ABV is closer to 2% or 6% (or hopefully eventually even higher)

If you mix the kombucha and wort together well enough to get a good gravity reading, the calculated ABV from the s.g. drop will be relatively accurate.

Also: would it not be possible to use the discrepancy between the hydrometer and refractometer readings to estimate the ABV (even without the original gravity reading)?

I don't think so, but you're welcome to try both methods to see how they compare, for science.

 

[MChai]

Are you thinking about adding wort instead of sugar and using an ale yeast? That's fine, and you can skip the nutrients since wort has plenty.

I was actually just going to do what I did with the champagne yeast: revive the yeast in sugar+water, and then add the yeast/sugar/water mix + yeast nutrient to the kombucha (after the first ferment). Do you suspect that won't work? I've never actually dealt with wort at all, just brewed kombucha for about a year and experimented with the champagne yeast for a few months.
(BTW, the yeast nutrient I have contains only diammonium phosphate, but I might splurge on some fancier stuff if needed)

I don't think so, but you're welcome to try both methods to see how they compare, for science.

Will do! (You had me at "for science" ) I'll report in a few weeks when it's all done.

Ah! Accidentally posted before I was done writing (oops! second post...). Anyway: thanks a bunch for your thoughts and suggestions!

 

[RPh_Guy]

Would you mind walking me through your plan? I'm not sure I understand.

 

[MChai]

Sure!
What I'd done before for just under 1/2 gallon was:
1) brewed normal kombucha (1st ferment), removed pellicule (but did not boil or otherwise try to kill the scoby in the liquid)
2) dissolved 100g sugar (I've used cane sugar, demerara sugar, and a mix of the two) in 1/2 cup boiled water, and when the mixture cooled to 37°C, added 1g champagne yeast.
3) I used a small toaster oven and food thermometer to keep the water-sugar-yeast mix between 35-37°C for 20 minutes. Sometimes I am able to see activity in the mix at that point, but more often than not it still looks inert.
4) dunked the water-sugar-yeast mix into my kombucha and added about 2.5g yeast nutrient.
5) poured all this into a 64oz growler, capped with an airlock, and left somewhere cool for 2-4 weeks (though I can usually still see bubbles when I shine a light into the growler even at 4 weeks, so maybe it's far from done?)
6) removed from growler, trying to leave as much of the yeast as possible undisturbed at the bottom (I tried to stir it up too, but turns out that the yeast I was using wasn't very tasty), added some flavoring (e.g., fruit, ginger, coconut water, etc.), and bottled for 2 days or so for a final ferment, then put in fridge.

(I'm leaving out any sterilization steps here, which I've generally performed, but also skipped at times.)

This yielded some tasty results, but I have no idea about the ABV. I know this is a pretty improvised/basic setup, but I'm holding off on purchasing equipment that'd be harder to transport, as I expect to move soon.

So, my plan now was to do essentially the same thing, but just use two new yeasts (separately, at least to start): Lallemand Belle Saison, and Escarpment Labs Laerdal Kveik. The only difference would be that now I can use a refractometer to check whether it's done fermenting.

Incidentally, until now, Lalvin EC-1118 worked far better for me than Red Star Premier Blanc (which produced fusils unless brewed below ~18°C, and even then my wife, who has a more discerning palate than mine, said there were some off flavors that I didn't notice myself).

Again thanks a bunch!

 

[RPh_Guy]

2) dissolved 100g sugar (I've used cane sugar, demerara sugar, and a mix of the two) in 1/2 cup boiled water, and when the mixture cooled to 37°C, added 1g champagne yeast.

Wine yeast should be rehydrated in water (+/- a rehydration nutrient) and then attemporated. (See the manufacturer instructions.)

2.5g yeast nutrient.

I highly recommend a yeast nutrient with amino acids (organic nitrogen) and vitamins, not just DAP.

5) poured all this into a 64oz growler, capped with an airlock, and left somewhere cool for 2-4 weeks (though I can usually still see bubbles when I shine a light into the growler even at 4 weeks, so maybe it's far from done?)

Using a hydrometer is the best way to measure fermentation progress. Bubbles don't provide definitive information. A refractometer could possibly be used instead.

turns out that the yeast I was using wasn't very tasty

It wasn't handled very well and that probably led to off flavors.

So, my plan now was to do essentially the same thing, but just use two new yeasts (separately, at least to start): Lallemand Belle Saison, and Escarpment Labs Laerdal Kveik.

Using beer yeast doesn't make it beer. Beer is made with malted barley and/or other cereal grains. Those yeast strains will work (and you'll need to follow my advice for them to work well because they're certainly less forgiving than EC-1118), but the result will be largely similar to what you've already been making.

One thing to keep in mind is that Belle is more difficult to remove than most yeast, and so you need a good cleaning procedure to prevent it from contaminating future batches.

Incidentally, until now, Lalvin EC-1118 worked far better for me than Red Star Premier Blanc (which produced fusils unless brewed below ~18°C, and even then my wife, who has a more discerning palate than mine, said there were some off flavors that I didn't notice myself).

EC-1118 (Red Star Premier Cuvee) is a great strain and it's very easy to use for newbies.

 

[MChai]

Thanks, RPh_Guy!

Wine yeast should be rehydrated in water (+/- a rehydration nutrient) and then attemporated. (See the manufacturer instructions.)

I was basically mashing up the manufacturer's instructions with the part of the Boochcraft recipe about rehydrating the yeast. I suspect they chose to rehydrate the yeast in the sugar solution so as not to have to dilute the kombucha with both the water + yeast mixture *and* water + sugar mixture. Is there a reason to suspect the extra sugar in the water would mess things up?

I highly recommend a yeast nutrient with amino acids (organic nitrogen) and vitamins, not just DAP.

Got some Yeastex now (which was really the only kind available for me to purchase at the moment).

Using a hydrometer is the best way to measure fermentation progress. Bubbles don't provide definitive information. A refractometer could possibly be used instead.

Will do moving forward. Since I'm brewing in my 1/2 gallon growlers, I'm going to try the refractometer to monitor (and use the hydrometer for OG and FG) - otherwise, by the time I'm done I won't be left with much to drink!

It wasn't handled very well and that probably led to off flavors.

Do you mean by me, at rehydration and/or later on in fermentation? I'll try and give the Red Star another chance and a bit more care, but I've been told that the Lalvin EC-1118 is a better bet. (Not sure why, though.)

Using beer yeast doesn't make it beer. Beer is made with malted barley and/or other cereal grains. Those yeast strains will work (and you'll need to follow my advice for them to work well because they're certainly less forgiving than EC-1118), but the result will be largely similar to what you've already been making.

Fair enough, I was just going for "beer" because I'm not exactly sure what else to call this. I've seen people call this stuff kombucha wine and kombucha beer, and also just plain hard kombucha, which is probably the best descriptor.

I haven't found much info online about brewing hard kombucha, so I'm basically working off the Boochcraft recipe (linked above) and slowly experimenting. I had a couple of meh batches, but the most recent was great. Now that I've done that, I feel ready to start experimenting, a bit, and changing the yeast strain seemed like a reasonable first step. I selected these yeast strains because as far as I can tell, they'll do reasonably well in an acidic environment.

One thing to keep in mind is that Belle is more difficult to remove than most yeast, and so you need a good cleaning procedure to prevent it from contaminating future batches.

Will letting stuff sit in a potassium metabisulfite solution do the trick?

Again, many thanks for your advice. I'm super new to this, and most of the info I can get my hands on is about brewing beer or wine, which sometimes doesn't neatly transfer over to kombucha... so your guidance is much appreciated.

 

[RPh_Guy]

Is there a reason to suspect the extra sugar in the water would mess things up?

Yes. The osmotic pressure damages the yeast while they are rehydrating since they cannot regulate the osmotic/sugar gradient.

Will do moving forward. Since I'm brewing in my 1/2 gallon growlers, I'm going to try the refractometer to monitor (and use the hydrometer for OG and FG) - otherwise, by the time I'm done I won't be left with much to drink!

FYI you can put a hydrometer sample back in.

Do you mean by me, at rehydration and/or later on in fermentation? I'll try and give the Red Star another chance and a bit more care, but I've been told that the Lalvin EC-1118 is a better bet. (Not sure why, though.)

Yes; yeast need proper rehydration, aeration, nutrients, temp control, etc. Otherwise it will likely produce off flavors.
EC-1118 is the same as Red Star Premier Cuvee, and this strain is very user-friendly as I mentioned. Red Star Premier Blanc (what you used before) is different, and requires more care.

I haven't found much info online about brewing hard kombucha

I'll have to write an article at some point.

For cleaning I recommend a warm soak with Oxiclean or generic, at minimum.

 

[MChai]

Yes. The osmotic pressure damages the yeast while they are rehydrating since they cannot regulate the osmotic/sugar gradient.

Interesting! The few other recipes I find online suggest rehydrating the yeast in the sugar solution, but I guess it's less of an issue for most folks if they are using the EC-1118 or a different forgiving strain (at least, the batches I brewed with that strain didn't seem to mind the sugar rush while waking up). Since you say the yeast strains I'll be using are less forgiving, I'll go with the manufacturer's recommendation and rehydrate the yeast in water, limiting the total amount of water added by warming a small portion of the kombucha, dissolving the extra sugar in that, and adding it back in to the rest of the batch.

FYI you can put a hydrometer sample back in.

You're the first to suggest that to me, actually. Most places I read suggest not to (because of the risk of contamination). Obviously, if you're keeping things sanitized it should be avoidable, but I don't yet feel quite confident enough that my beginner sanitizing routine will cut it.

Yes; yeast need proper rehydration, aeration, nutrients, temp control, etc. Otherwise it will likely produce off flavors.

Well, I'll see how it goes... my most recent batch (which the EC-1118 had been going in for ~4 weeks) had an FG of 1.008 and tasted great (~4.5% ABV), and hopefully a bit of TLC will make the next batches even better

Thanks again!

 

[RPh_Guy]

The hydrometer sample is the least of your worries regarding contamination if you're following instructions from any of the kombucha sites I've seen.