Pressure to carb ratio?

[johnnyseko]

So I thought I had this figured out and pasteurized my bottles after achieving @26psi on the test bottle. After refrigerating for a week and cracking them open, got the pffft. Pouring into a glass I expected tiny bubbles rising in the glass indicating a medium or even sparkling carb. Not the case. Pretty flat besides the 'feel' of carb if you swish around.

Not sure if I did anything wrong, all bottles were together during carb and I even weighed them to be sure they had the same amount in ml when bottling. Headspace was @1.5" from top of 12oz bottle. Same result on two separate batches done at different times. I just got the gauge - I don't need to calibrate it, do I? Do the bottles need to chill longer to absorb the co2?

Is there a pressure I should shoot for? I'm afraid to go too high because I'm pasteurizing. Haven't had a breakage yet though. Pasteurizing at 155F for 10 minutes.

 

[Maylar]

Nope, you did it right. If all bottles had the same amount of priming sugar then 26 psi at room temp would give you about 2.4 volumes of CO2.

 

[johnnyseko]

Cool. I had expected a bit more fizz at that pressure - like most commercial ciders. Do you think more or less headspace? More time chilled to absorb co2? All bottles turned out the same and were chilled from 7-10 days.

I'm bottling my pumpkin chai this week. Might sweeten to 1.005 with maple and pasteurize. This gauge is awesome. Just need to tweak the process a bit.

 

[Bombo80]

My question is "How many days has it been since you bottled, and then reached the 26 PSI on your test bottle ?"

 

[Maylar]

I let mine go to 25 psi then refrigerate. I know some commercial ciders are much higher than 2.4 volumes, but beyond that and you risk catastrophic failure with pasteurizing.

 

[johnnyseko]

My question is "How many days has it been since you bottled, and then reached the 26 PSI on your test bottle ?"

Caramel Apple took just 4 days to reach 26psi. Sat out for a week after pasteurizing, then another week in the fridge before enjoying. I still have a six pack chilled and will keep it for a month or more to see if that helps.

Cranberry took 9 days to reach 24psi, (sweetened with only honey and just enough priming sugar SG 1.008) pasteurized then was chilled immediately and consumed about a week later.

 

[Bombo80]

It has been a while since I have bottle carbed a cider. I usually keg and force carb, or use 2 liter PET bottles and force carb with the carbonator cap.

I don't think that just because your bottles are reaching a proper PSI that there is enough CO2 in them for proper carbonation.

When I use the carbonator cap, I set the PSI to 45 pounds, fill the bottle, shake for 30 seconds then top off the CO2 and put them in the fridge. I do this process twice a day for 3 days and have a very nice carb level on my ciders.

I am wondering if there is a slightly different twist on your procedure that needs to be done. We all know that CO2 dissolves better and faster in a cold liquid. You might have to experiment with this. Leave a few at room temp and stagger putting them in the fridge at different pressures. Monitoring the chilled pressures and sample along the way. Take good notes as you go.

I have only let them go until the sample bottle has the carb level I am looking for, then pasteurize. This is also why I prefer a lower pasteurizing temp also. It helps eliminate any bottle bombs during the pasteurization process.

I like your plan with the regulator. It just needs some tweeking to get it right.

 

[johnnyseko]

I am wondering if there is a slightly different twist on your procedure that needs to be done. We all know that CO2 dissolves better and faster in a cold liquid. You might have to experiment with this. Leave a few at room temp and stagger putting them in the fridge at different pressures. Monitoring the chilled pressures and sample along the way. Take good notes as you go.

This has me thinking......Say I take my tester that is at 25psi and chill it. The pressure drops - I'd assume the co2 went into solution. Or is that simply due to temperature changing the density of the air? If I take it out of the fridge to warm to allow the yeast to get active again, will the original co2 come back out as it warms and the pressure builds too high? Or will the co2 stay in solution and I can allow the yeast to produce more co2 into the headspace which will eventually go into solution as well when I chill again.

Or should I get a keg...lol

 

[ten80]

This has me thinking......Say I take my tester that is at 25psi and chill it. The pressure drops - I'd assume the co2 went into solution. EXACTLY. Or is that simply due to temperature changing the density of the air? NO. If I take it out of the fridge to warm to allow the yeast to get active again, will the original co2 come back out as it warms and the pressure builds too high? YES AND NO. Or will the co2 stay in solution SOME OF IT WILL and I can allow the yeast to produce more co2 into the headspace which will eventually go into solution as well when I chill again YES.
Or should I get a keg...lol YES, but bottling has its advantages

You have the basic concept right, but I would like to clarify what happens to the CO2 as it goes into solution.

CO2 produced by yeast initially causes pressure in the bottle to increase as CO2 fills the headspace. The increased pressure causes CO2 and H2O to combine and form H2CO3 (carbonic acid) which dissolves into solution. H2CO3 builds up until an equilibrium is reached with the CO2 in the headspace. The equilibrium is heavily influenced by temperature, warming the solution will shift it towards CO2 and cooling towards H2CO3.

When carbonating the equilibrium is towards carbonic acid: CO2 + H2O -> H2CO3
IF beer is warmed the equilibrium shifts towards CO2: CO2 + H2O <- H2CO3

SO..... the factors affecting carbonation include:
-Amount of priming sugar
-Temperature
-Pressure
-pH (a factor, but not doesn't have much importance at standard beer pH)
-Reaction kinetics (time for CO2 to dissolve into solution as H2CO3)

The take-away message is that you should carbonate at room temperature until the pressure in the bottles remains constant, then chill, wait till the pressure drops and stabilizes, then use the final pressure reading to determine your volumes of CO2 at your intended serving temperature.

Here's a read on the solubility of CO2 in water as defined by Le Chatelier's Principle https://sciencehsc.wordpress.com/tag/le-chateliers-principle/

 

[johnnyseko]

I just bottled another batch @1.006SG. Using the tester I might cycle warm/cold and watch what happens with the pressure. I'll see if I can get it to hold @25psi warm and cold after a few cycles. Similar to what bombo80 described with the carbonator cap but I'll use the yeast to do the work of adding more co2 pressure during each warm cycle.

 

[Maylar]

What I've seen is that at 25 psi room temp if I put the test bottle in a fridge at 40 F the pressure drops to 12 psi or so just as the charts predict. It'll return to 25 if you let it warm up again but it takes a while.

 

[johnnyseko]

That sounds the same as mine, when I chilled the tester. I'll split my new batch up and pasteurize half at 25 and experiment with the others to see if there's a difference in carb. It's only 10-12oz's from a gallon batch. Already 8psi since bottling yesterday.

Dave, how long do your batches take to reach 25?

 

[Maylar]

Depends on yeast and temperature and how long the cider was in secondary before bottling, but typically 2-3 weeks.

 

[johnnyseko]

Mine are pressurizing really fast in comparison. Especially the caramel apple, that had a lot of extra sugar and no secondary. Might just need more time to absorb that co2. I know my standard primed bottles take @4 weeks to carb up so that gives plenty of time to get the co2 into solution. I'll keep notes on the current batch and report back how this turns out.

 

[Maylar]

Just a thought - bottle conditioning isn't the same as forced carbonation. In a keg the CO2 is coming from outside and has to be absorbed by the solution. With bottle carbing the CO2 is coming from within the solution as the yeast create it. I don't know if the same rules about temperature vs absorption apply.

 

[johnnyseko]

I finally have to call my experiment finished (as all of the cider is gone....) This probably proved more how much patience I lack!

My batch (SG 1.006) of 9-12oz bottles went from zero to 25psi in 5 days @72F. I pasteurized three of the bottles and chilled them for about a week before trying. Very light carb upon sampling.

The remaining six were put in the fridge to see if I could get more PSI into the chilled beverage by cycling warm/cold several times. When the gauge appeared to pause at the low end, I would bring them back out to warm. Allowing them to go back to 25PSI in hopes the yeast would get active for a bit again, producing more CO2 which would get absorbed when chilled. Here are the figures after dropping them in the fridge starting at 25PSI:

Time -- Temp -- PSI

24Hrs 44F = 16PSI
25Hrs 72F = 25PSI
33Hrs 44F = 18PSI
13Hrs 72F = 25PSI
21Hrs 44F = 18PSI
14Hrs 72F = 25PSI
4 days 44F = 19PSI

I got lazy at the end and just didn't want to have to keep cycling anymore. If it's much more work than this it just wouldn't be worth it for future batches. It appears I gained 3PSI which actually showed in the results upon sampling. Well, it was more than sampling. I had wanted to pasteurize these as well just to make them exact like the first three. The resulting light carb was just fine, an obvious increase from the first three. They didn't last long enough to get pasteurized. I'll probably do some more testing with this in future batches. The resulting fizz was definitely worth the effort.