Yes, I know we have had lots of posts on this topic, but I figured that my recent (somewhat successful) experience might "add to the body of knowledge".
I finally got around to trying stovetop (or heat) pasteurising. In my case I used SWMBO’s electric preserving bath (reasonably easy to control the temperature by turning it on and off, etc).
I had mixed success with the process but am quite happy with the results. By accident rather than design, on reflection the first batch more or less followed the Cooler Pasteurisation method proposed by JimRausch and others, even though I was trying to be a bit “scientific” by measuring temperatures, bottle pressure and times etc.
The second batch produced one bottle bomb because I let the temperature get too high 68C (155F) for too long (26 minutes including pre-heating!) while I was monitoring bottle pressure without realising that the pressure gauge seal was leaking. KABOOM, Duh!
Sadly because of this I wasn’t able to determine how much bottle pressure was generated at Kaboom time as I was looking to see what temperature and time combination lets the pressure stay well below the “safety limit” for used beer bottles.
From what I can determine, about 50psi (a bit over 3 atmospheres) is about the limit. The plan is to make a better monitoring rig and maybe post some time, temperature and pressure figures. Incidentally the bottle that blew was a used 333ml Heinekin that weighed 10g less than the others in the batch (the others were all in the 195 -205g range). Maybe it was an underspec or flawed bottle, but still too close for comfort. All part of the learning process folks!
Anyhow, the reason for posting all of this is to suggest that off-dry petillant cider is reasonably easy without blowing up the kitchen. The idea is to understand the concept of using Pasteurisation Units (PUs) to stop fermentation, which explains why the Cooler Pasteurisation and similar Stovetop type pasteurisation methods work.
I first came across the idea of PUs in Bembel’s post of 5 May 2016 while scratching around on the forum, and PU monitoring seems to be common practice in brewing for setting up the process for pasteurising beer. Basically 1 PU results from heating the brew to 60C (129F) for one minute. More temperature or more minutes equals more PUs. However, the “trap” is that the bottle pressure rises somewhat exponentially with increasing temperature as CO2 is forced out of the liquid and expands into gas in the bottle airspace, so many of us have been reluctant to risk kabooms.
The “rule of thumb” seems to be that for cider, you need 50 PUs to kill the yeast to stop fermentation and stop carbonation, although this figure is a bit rubbery as there is quite a wide range of figures quoted in the literature. For example, most breweries seem to work on 15 -25 PUs. Nevertheless, 50 PUs for amateur cider makers seems to be a conservative target with a fair margin of safety. I guess that what this means is that the pasteurisation process doesn't need to be controlled very precisely as any number between 30 and 50 will probably do the job.
So using the PU approach, a carbonated cider with some sweetness should be possible, especially with some method of measuring how many atmospheres (or psi) are in the bottle at the time of pasteurisation. (A pressure gauge set up on a test bottle or by estimating from the rate of fermentation where 0.001 SG drop = 0.51 atmospheres of CO2)
e.g. bottle at SG 1.010, let 2 atm (around 30 psi) of pressure develop (from a SG drop of about 0.004), then heat pasteurise to stop fermentation and get a slightly sweetened, carbonated cider that is 1.006.
Mind you, without getting too scientific about it, Jollicoeur quotes 10 minutes at 65C (149F) which results in about 50 PUs according to the following formulas and this also is roughly in line with what happens with the various Cooler Method posts on this forum.
Anyhow, the scientific bit for those who are interested, is that you can determine the temperature and time needed to stop fermentation by monitoring how many PUs are generated from heating the bottled cider. Setting up a spreadsheet to do the calculations and monitor progress is quite straightforward, or (shock horror!) you can even use a pencil and paper.
There seems to be two formulas in common use which result in roughly the same answers, based on temperatures at or above at 60C (140F) which is the minimum for pasteurisation to take place.
(1).....PUs in 1 minute =1.393^(T-60) where T=temperature
(2).....PUs in one minute= (10^((T-60)/7) where T = temperature
At 65C (149F), Formula 1 gives 5.25 PUs per minute and Formula 2 gives 5.18 PUs per minute. Not quite the same but near enough as they both result in approximately 50 PUs over about 10 minutes.
So, allowing for a few PUs in the heating up and cooling down phases, the Cooler Pasteurising methods come pretty close to this (maybe even a bit over) with minimum risk of bottle bombs and overcooked taste.
Feel free to discuss, challenge or whatever in relation to this but I hope it helps with trying to understand how to achieve the "Holy Grail" of sweetened carbonated cider.
Phew, now what I need is a nice off dry petillant carbonated, cool cider!!!
I finally got around to trying stovetop (or heat) pasteurising. In my case I used SWMBO’s electric preserving bath (reasonably easy to control the temperature by turning it on and off, etc).
I had mixed success with the process but am quite happy with the results. By accident rather than design, on reflection the first batch more or less followed the Cooler Pasteurisation method proposed by JimRausch and others, even though I was trying to be a bit “scientific” by measuring temperatures, bottle pressure and times etc.
The second batch produced one bottle bomb because I let the temperature get too high 68C (155F) for too long (26 minutes including pre-heating!) while I was monitoring bottle pressure without realising that the pressure gauge seal was leaking. KABOOM, Duh!
Sadly because of this I wasn’t able to determine how much bottle pressure was generated at Kaboom time as I was looking to see what temperature and time combination lets the pressure stay well below the “safety limit” for used beer bottles.
From what I can determine, about 50psi (a bit over 3 atmospheres) is about the limit. The plan is to make a better monitoring rig and maybe post some time, temperature and pressure figures. Incidentally the bottle that blew was a used 333ml Heinekin that weighed 10g less than the others in the batch (the others were all in the 195 -205g range). Maybe it was an underspec or flawed bottle, but still too close for comfort. All part of the learning process folks!
Anyhow, the reason for posting all of this is to suggest that off-dry petillant cider is reasonably easy without blowing up the kitchen. The idea is to understand the concept of using Pasteurisation Units (PUs) to stop fermentation, which explains why the Cooler Pasteurisation and similar Stovetop type pasteurisation methods work.
I first came across the idea of PUs in Bembel’s post of 5 May 2016 while scratching around on the forum, and PU monitoring seems to be common practice in brewing for setting up the process for pasteurising beer. Basically 1 PU results from heating the brew to 60C (129F) for one minute. More temperature or more minutes equals more PUs. However, the “trap” is that the bottle pressure rises somewhat exponentially with increasing temperature as CO2 is forced out of the liquid and expands into gas in the bottle airspace, so many of us have been reluctant to risk kabooms.
The “rule of thumb” seems to be that for cider, you need 50 PUs to kill the yeast to stop fermentation and stop carbonation, although this figure is a bit rubbery as there is quite a wide range of figures quoted in the literature. For example, most breweries seem to work on 15 -25 PUs. Nevertheless, 50 PUs for amateur cider makers seems to be a conservative target with a fair margin of safety. I guess that what this means is that the pasteurisation process doesn't need to be controlled very precisely as any number between 30 and 50 will probably do the job.
So using the PU approach, a carbonated cider with some sweetness should be possible, especially with some method of measuring how many atmospheres (or psi) are in the bottle at the time of pasteurisation. (A pressure gauge set up on a test bottle or by estimating from the rate of fermentation where 0.001 SG drop = 0.51 atmospheres of CO2)
e.g. bottle at SG 1.010, let 2 atm (around 30 psi) of pressure develop (from a SG drop of about 0.004), then heat pasteurise to stop fermentation and get a slightly sweetened, carbonated cider that is 1.006.
Mind you, without getting too scientific about it, Jollicoeur quotes 10 minutes at 65C (149F) which results in about 50 PUs according to the following formulas and this also is roughly in line with what happens with the various Cooler Method posts on this forum.
Anyhow, the scientific bit for those who are interested, is that you can determine the temperature and time needed to stop fermentation by monitoring how many PUs are generated from heating the bottled cider. Setting up a spreadsheet to do the calculations and monitor progress is quite straightforward, or (shock horror!) you can even use a pencil and paper.
There seems to be two formulas in common use which result in roughly the same answers, based on temperatures at or above at 60C (140F) which is the minimum for pasteurisation to take place.
(1).....PUs in 1 minute =1.393^(T-60) where T=temperature
(2).....PUs in one minute= (10^((T-60)/7) where T = temperature
At 65C (149F), Formula 1 gives 5.25 PUs per minute and Formula 2 gives 5.18 PUs per minute. Not quite the same but near enough as they both result in approximately 50 PUs over about 10 minutes.
So, allowing for a few PUs in the heating up and cooling down phases, the Cooler Pasteurising methods come pretty close to this (maybe even a bit over) with minimum risk of bottle bombs and overcooked taste.
Feel free to discuss, challenge or whatever in relation to this but I hope it helps with trying to understand how to achieve the "Holy Grail" of sweetened carbonated cider.
Phew, now what I need is a nice off dry petillant carbonated, cool cider!!!
