Bottle Carbing Idea (Final Data Review)
Well I started the Pasteurization today and I have data and plots showing the Carbonation process, as well as the Pasteurization process.
I started slightly early in the pressure rise. I was actually looking for 2.5 volumes of CO2, for a pressure of 25.3 Psi, but my basement temperature has been moving around a couple degrees as the weather is changing back and forth here in New York. This ends up changing the carbonation pressure required for a given number of volumes. I ended up doing this with 22 Psi for 2.3 volumes of CO2 as I have company coming to dinner Sunday.
The carbonation process and conditioning of the bottles with a priming sugar added for 2.5 Volumes worked quite well with the plastic test bottle, with no indications of failure of either the tapped threads for the gauge or the bottle itself.
The process seems to be fairly linear over time, with a slight wander in the pressurization rate most likely due to variation in my basement temperature. Temperature will have a big impact on carbonation time.
The following data and plots show this pressurization rate.
edit: more info regarding cider prior to bottle conditioning.
Cider fermented to 1.012 using Safale S-04
Cider bottled with priming sugar added for 2.5 Volumes of CO2 on top of the finished 1.012 SG.
Cider bottle conditioned for ~ 11 days at around 62 - 66 deg
Pressure Monitored during the 11 Days, waiting for 25.3 Psi to produce 2.5 Volumes CO2.
No Cold Crash Done.
Pasteurization started at actual 22 Psi for 2.3 Volumes CO2.
Pasteurization detailed below.
Overall, the process followed what appears to be typical when following the normal priming wait time before Pasteurization which is described quite well by Pappers sticky post.
There may be some variation in this however which could be attributed to strain of yeast and sugar content (SG) prior to adding priming sugar. This was with Safale S-04, and a final SG reading of around 1.012.
From my experience with Champagne yeast, and how vigorous that strain is, the rates could be quite different. This would support using some kind of gauging method to reach the desired pressurization value prior to Pasteurization and add a safety factor. I don't have any data using Champagne yeast yet to determine if a more aggressive yeast would change rates, however I hope to continue testing on using more than one strain to see if the rate is typical for all strains or not.
I began by putting the test bottle in a water bath of 160 degrees, with the flame off. I covered the pot with 2 towels too keep heat in as well as the water in the event the bottle burst. I recorded the pressure rise with samples at 1 minute intervals. As it turns out, the pressure inside the bottle is much higher than one might think. As you can see from the data, my 30 Psi gauge was not adequate for the Pasteurization task.
The pressure inside the bottle went way above 30 Psi. In fact the pressure did not drop and come off the 33 Psi hard stop on the gauge for almost 3 hours. As of this writing, the pressure is still above 30 Psi. The following data shows the Pasteurization process.
I think that the general process of using the typical methods does work in most cases. I believe the unknowns and the method of applying Pasteurization heat with a water bath does work well, however how high a temperature of the bath will have a large impact on how high the pressure goes during that process.
Pimento has found some data regarding the temperatures that yeasts die off at, and I hope he posts that data here. However, I did use a temperature for the bath that would fall in line with his data, and would get the liquid temperature up in the 140's. If I recall correctly, his data suggests that this temperature would be fatal for the yeasts. It would also help keep the bottle pressures lower durring that process.
I used a bath temperature of 160 degrees, with a submersion time of about 12 minuets. As you can see from the data collected during the Pasteurization, the pressure climbs fairly linearly with time and with the temperature of the liquid in the container.
I wasn't able to determine the actual pressure in the bottle due to the limit of the gauge. It might make sense to use a 50 or a 100 Psi gauge for this whole process (depending on your CO2 Volumes and Pasturization Temperatures). I was able to estimate the pressure in the bottle using linear regression of the data. This of course is only a estimate, however in all likelihood a good estimate as I believe pressure of a gas increases linearly with temperature in a fixed volume.
There are a few things that may have a large impact on whether you have bottles burst during this process or not. If the bottles are submerged to a level that is either approaching or above the liquid level, the gas temperature would rise much faster than my data shows, which would cause the pressure to climb at a very rapid rate, and likely exceed what I saw or estimated. I had the water about 2/3 the way up the bottle liquid level. I think there is a fairly good chance you could blow a bottle if the water level gets a lot higher.
With all of this said, typical methods do provide a pretty good safety margin, however refining the method to provide safety and repeatability of carbonation might suggest that this method may have merit.
I think in the end, we are really force carbing the Cider like the keggers do. We raise the pressure way up, and the cider dissolves the CO2 and the pressure drops. I'll post a vid showing the Carb level I have.
Any comments or suggestions are welcome. YMMV.
That is awesome info... and reassures my suspicion and nervousness about bottle pasteurizing.
Backward linked to previous thread addressing this idea:
With all of this data, I think it suggests that if you don't use a gauge to pasteurize, make sure you calculate your sugar right, wait the (week with tests durring the week to check for overcarb) and then use a lower temperature to pasteurize. Perhaps 160 to 165 for 12 or so minutes. Do your normal "test a bottle every few days" , or squeeze the bottle if thats what works for you, but in either event use a lower temperature for pasteurization.
Also, don't fill the pasteurization pot above 2/3 the bottle liquid level. I would also place a towel over the top even if you use a lid to help contain the splash of hot liquid in case of a bottle failure.
Even more importantly, do not overfill the bottle. Leave the typical 1.5" to 2" of a longneck airspace. The shorter headspace will likely bring the pressure even higher and cause a failure at typical pasteurization temperatures.
I'll attempt to get data with other temperatures and strains of yeast.
edit: I'll leave the gauge on the test bottle to see what the pressure drops back down to, and monitor to see if the yeast takes off again. I don't think it will with the info I have, but can't be to safe.
another edit: It just occured to me some people use larger volume bottles. This was with a 12 oz. Long neck. I'll see if I can dig up a pounder and do the same thing. Perhaps a quart as well. The pasteurization time may have to be extended longer than 12 min.
Wait time is one week, but with tests during wait.
To be clear, are you adding priming sugar to a dry, cold crashed, racked cider?
Because I recently cold crashed a fermenting cider at 1.020 ... bottled... and tested 12 hours later and had adequate carbonation. If noobs read this, and think it will take two weeks for their sweet cider to carbonate in the bottle before pasteurizing, someone is going to die. Can you give more info, preferably edited into your OP, about the cider going into your experiment?
My attempt was to eliminate back sweetening and still get the proper carbing for the sweetness I wanted.
I'll check one of the bottles for SG to see if all of the priming sugar was used and I'm back to the original SG I wanted.
I probably won't get that data until tomorrow morning as I would have to open a bottle and drink it. I just finished my 3rd Guiness, and I have to test my newly kegged Ale. I think I'll be full by then ;)
We have to consider the data I've provided as a data point of One. This has only been done once. However, following the current and well tested methods would produce the same result if a "Noob" (myself included) followed the current method with a more aggressive fermentation after bottling, and have one go off in the pot.
That is the reason why I think that using a gauge is a better method than basically winging it. I'm trying to be careful in my examination of current methods so that I do not offend Pappers as he has put allot of effort in his explanation of Pasteurization, and in general is a proven method as many use his method with excellent results, but many people don't understand the dangers not knowing the forces we are dealing with. I personally don't want to see someone get hurt.
The whole problem is currently there is no measure of "where you are" when you drop them in the pot other than a subjective test.
All this said, I still think that any way folks decide to pasteurize, lower temperatures can be used which should provide a bit more leeway in the safety factor.
This testing is provided as is, and is in no way totally complete. There are too many factors that can cause a failure without adequate measuring capability.
Edit. Cold crashing is not going to keep the yeast from taking off anyway as you'd never get carbonation in the first place if it did.
Priming calculations and Priming calculators are available on the web. You just enter the type of carbonation you want by style or just enter the number of volumes you want.
I'm just trying to understand what you considered sufficient for your need.
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