I will post this in the stovetop sticky thread as well, but this way people can get the information without having to read through 126 pages.
Basically, you can pasteurize at much lower temps, and as a result, maintain lower pressures, and as a result, suffer fewer bottle bombs, than what is recommended as 'standard' by most of the information on this website regarding stovetop pasteurization.
Different ciders, be they still or sparkling, have different yeast loads and require different amounts of PUs to stabalize them.
But the net-net is that the methods outlined in most of the threads here = are OVERKILL and therefore unnecessarily dangerous at the temperatures they recommend and pressures that result.
First, we need to understand what a PU is and have a system for measuring them. Here is an EXCELLENT summary, (the formula has been simplified to remove the exponents and assumes a constant of 60, but this is good for cider and beer)
One pasteurization unit is the microorganism death that occurs in a product held at 60°C for 1 minute.
The number of PU's required for a particular beverage depends on several factors, such as the microrganisms it contains and even on the type of packaging.
The success of pasteurization (that is, what percentage of the microrganisms are killed) is affected by both temperature and by the length of time for which the product is held at that temperature. It is a tradeoff: high temperatures for short times or lower temperatures for longer times. Unfortunately, higher temperatures tend to affect the taste of the beverage.
The total number of PU's for a particular pasteurization processes for beer (or cider, roughly the same ABV) can be estimated from²:
PU = t × 1.393(T − 60)
where T is the temperature in degrees Celsius, and
t is the time in minutes at which the beer is held at that temperature.
In reality, of course, the beverage does not instantaneously go to the desired temperature, nor does it cool down instantaneously.
OK, so where do we go now?
Basically, with a semi-sweet cider that still has a lot of yeast in suspension or fresh apple juice the rule of thumb in Ciderville (nod to Ria and Cider Chat :rockin
is 50 PUs. My ciders stabalize at 25 PUs since they are dry ( 1.001-002 ) when I start, have very little active yeast and already have an ABV of 6-7% So 50 PUs is overkill for me, 25-30 is just fine.
Either way, to get 50 PUs you don't need a water bath at 190F for 10 min. That would get you over 1500 PUs, which would cook a cow
PUs basically start at 140F ( 60C) and you can get 50 PUs without ever going above 65F (149F) and do so in under 15 minutes total time.
Why is this important? Well, personally, I'd rather not screw around with 190F water and pressurized bottles when I can do the same with 149F water, get my point?
Also, its pointless to even discuss PUs without having a way to monitor the temp INSIDE each bottle, and that's just a #3 stopper and a $15 digital thermometer away.
So, in a nutshell
Get a thermometer that you can stick through a #3 cork, the DOT by Themoworks is perfect for this, http://www.thermoworks.com/DOT but cheaper ones work
Fill an empty bottle of the same size of those that you are pasteurizing with water and stick the probe in.
Place all your bottles (including the temp. monitor one) in your sink full of the hottest tap water you can get (I get mine up to about 120F, see photo ) and let it sit there until the temp monitor bottle stabilizes, while this is happening work on the water bath for the actual pasteurization.
Get the water in your water bath for pasteurizing up to 70C, but 68C will also work ( 155-160F). I use an Anova sous-vide immersion cooker to maintain this, but you can experiment with different stove settings and perhaps if this is not an option. If you use an Anova immersion cooker, it has digital temp control and an impeller motor that circulates the water. You do not need a rack for the bottles as there is no direct heat, and the temp is maintained within .5C, there are no hot/cold spots. If you want to use the stove, play with the temps and a half full pot until you get them to stabalize at 70C (158F) If you brew beer and have a pump / immersion chiller or HERMS/ RIMS system all of these can be repurposed to do this.
(You can ALSO use strike water temp calculators from beer mashing to get the right temps/volumes and rather than heat in pot on the stove, dump hot water into an old cooler to do the same thing, a lot safer too, if working with carbonated bottles, as you can close the cooler lid and if anything pops, well, it's quite contained)) - again, a RIMS system or HERMS system hooked up to your mash tun would be a fantastic way to re-purpose that equipment for pasteurizing)
So now I lower 12 bottles into my 68C water bath, and count the number of seconds at each temp, add them to an excel sheet I made to do the math, based on the minutes at each temp times the PUs at that temp, and pull them out when they have accumulated around 35 PUs, knowing the few minutes of cool down will also add to the total PUs leaving me with just under 50 Pus. This is what the times / temp look like ( see attached chart)
In this example, I used too low a strike temp (63C) so the total time was over 20 min from start to finish.
I now start at 70C and my total times are closer to 12 minutes, as the initial temps climb up to 60C much faster.
The Net-Net?
You just need to measure your PUs and not guess.
If you need 50PUs You can get there with water as low as 150F in a short amount of time, and that's a lot safer than working with near boiling temps which will increase the pressure in the bottles exponentially.
Maylar has some excellent info regarding bottle pressure, and I thank him for his contributions
Here is the link to the Excel sheet with the formulas for converting time at temp to PUs, fill in the yellow boxes, and enter time including 0 for the hour as 0:mm:ss and the sheet will convert that to decimal minutes as well.
https://www.dropbox.com/s/5vkkhmsd722z4ry/PU chart for Cider.blank.xlsx?dl=0
Here are pics of the initial warm up pre-pateurization bath and the actual pasteurization using the sous vide immersion cooker
Basically, you can pasteurize at much lower temps, and as a result, maintain lower pressures, and as a result, suffer fewer bottle bombs, than what is recommended as 'standard' by most of the information on this website regarding stovetop pasteurization.
Different ciders, be they still or sparkling, have different yeast loads and require different amounts of PUs to stabalize them.
But the net-net is that the methods outlined in most of the threads here = are OVERKILL and therefore unnecessarily dangerous at the temperatures they recommend and pressures that result.
First, we need to understand what a PU is and have a system for measuring them. Here is an EXCELLENT summary, (the formula has been simplified to remove the exponents and assumes a constant of 60, but this is good for cider and beer)
One pasteurization unit is the microorganism death that occurs in a product held at 60°C for 1 minute.
The number of PU's required for a particular beverage depends on several factors, such as the microrganisms it contains and even on the type of packaging.
The success of pasteurization (that is, what percentage of the microrganisms are killed) is affected by both temperature and by the length of time for which the product is held at that temperature. It is a tradeoff: high temperatures for short times or lower temperatures for longer times. Unfortunately, higher temperatures tend to affect the taste of the beverage.
The total number of PU's for a particular pasteurization processes for beer (or cider, roughly the same ABV) can be estimated from²:
PU = t × 1.393(T − 60)
where T is the temperature in degrees Celsius, and
t is the time in minutes at which the beer is held at that temperature.
In reality, of course, the beverage does not instantaneously go to the desired temperature, nor does it cool down instantaneously.
OK, so where do we go now?
Basically, with a semi-sweet cider that still has a lot of yeast in suspension or fresh apple juice the rule of thumb in Ciderville (nod to Ria and Cider Chat :rockin
is 50 PUs. My ciders stabalize at 25 PUs since they are dry ( 1.001-002 ) when I start, have very little active yeast and already have an ABV of 6-7% So 50 PUs is overkill for me, 25-30 is just fine.Either way, to get 50 PUs you don't need a water bath at 190F for 10 min. That would get you over 1500 PUs, which would cook a cow
PUs basically start at 140F ( 60C) and you can get 50 PUs without ever going above 65F (149F) and do so in under 15 minutes total time.
Why is this important? Well, personally, I'd rather not screw around with 190F water and pressurized bottles when I can do the same with 149F water, get my point?
Also, its pointless to even discuss PUs without having a way to monitor the temp INSIDE each bottle, and that's just a #3 stopper and a $15 digital thermometer away.
So, in a nutshell
Get a thermometer that you can stick through a #3 cork, the DOT by Themoworks is perfect for this, http://www.thermoworks.com/DOT but cheaper ones work
Fill an empty bottle of the same size of those that you are pasteurizing with water and stick the probe in.
Place all your bottles (including the temp. monitor one) in your sink full of the hottest tap water you can get (I get mine up to about 120F, see photo ) and let it sit there until the temp monitor bottle stabilizes, while this is happening work on the water bath for the actual pasteurization.
Get the water in your water bath for pasteurizing up to 70C, but 68C will also work ( 155-160F). I use an Anova sous-vide immersion cooker to maintain this, but you can experiment with different stove settings and perhaps if this is not an option. If you use an Anova immersion cooker, it has digital temp control and an impeller motor that circulates the water. You do not need a rack for the bottles as there is no direct heat, and the temp is maintained within .5C, there are no hot/cold spots. If you want to use the stove, play with the temps and a half full pot until you get them to stabalize at 70C (158F) If you brew beer and have a pump / immersion chiller or HERMS/ RIMS system all of these can be repurposed to do this.
(You can ALSO use strike water temp calculators from beer mashing to get the right temps/volumes and rather than heat in pot on the stove, dump hot water into an old cooler to do the same thing, a lot safer too, if working with carbonated bottles, as you can close the cooler lid and if anything pops, well, it's quite contained)) - again, a RIMS system or HERMS system hooked up to your mash tun would be a fantastic way to re-purpose that equipment for pasteurizing)
So now I lower 12 bottles into my 68C water bath, and count the number of seconds at each temp, add them to an excel sheet I made to do the math, based on the minutes at each temp times the PUs at that temp, and pull them out when they have accumulated around 35 PUs, knowing the few minutes of cool down will also add to the total PUs leaving me with just under 50 Pus. This is what the times / temp look like ( see attached chart)
In this example, I used too low a strike temp (63C) so the total time was over 20 min from start to finish.
I now start at 70C and my total times are closer to 12 minutes, as the initial temps climb up to 60C much faster.
The Net-Net?
You just need to measure your PUs and not guess.
If you need 50PUs You can get there with water as low as 150F in a short amount of time, and that's a lot safer than working with near boiling temps which will increase the pressure in the bottles exponentially.
Maylar has some excellent info regarding bottle pressure, and I thank him for his contributions
Here is the link to the Excel sheet with the formulas for converting time at temp to PUs, fill in the yellow boxes, and enter time including 0 for the hour as 0:mm:ss and the sheet will convert that to decimal minutes as well.
https://www.dropbox.com/s/5vkkhmsd722z4ry/PU chart for Cider.blank.xlsx?dl=0
Here are pics of the initial warm up pre-pateurization bath and the actual pasteurization using the sous vide immersion cooker
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