Accumulation of pasteurization units

[Søren Ugilt Larsen]

Dear all,

Although this topic has been discussed often in this workshop (e.g. in this nice tread: Pasteurisation and PU's (google.com), I dare asking about it again - and share a bit of experience:)

I have made an ice cider which had reached the desired SG level. I did not succeed (or did not have the patience to succeed...) with multiple rackings to stabilize the cider, so I decided to do in bottle pasteurization. I tried to follow the general recommendation (e.g. in Claude’s book) of heating to 65C for 10 minutes to ensure accumulation of 50 PUs. I measured temperature in a 'blind' bottle with an Inkbird temperature logger (logging at 10 seconds interval), and the heating was controlled by a thermostat. To be on the safe side, I ended up with 12 minutes at 65-66C after which I poured out the water and tilted the bottles to let the warm ice cider get into contact with the cork.

Subsequently, I have had a look on the temperature data, and since it took a rather long time to reach the target temperature of 65C, I ended up accumulating 137 PUs above 60C, even without including the PUs accumulated during cooling. In fact, the 50 PUs were reached already after approx. 1 minute at 65C (see attached figure). This means that I may have overdone the pasteurization considerably. 

My question is now, if I should rely on these data for my next pasteurization (assuming the same heating setup etc.) and simply stop the pasteurization after about 1 minute at 65C?

I have to admit, that I have not tasted the pasteurized ice cider yet, so I can’t judge the effect on taste. Also, it is too early to tell, if refermentation will occur in the test bottle which is placed at 20-25C. 

Best wishes 

Søren

[tanja s]

Hi Soren,

Do you have one of those fancy Craft monitors to measure the PU? Or how do you do it? I looked a the thread, looks very long;) thought May be you could point out to one them, if it’s not the 500$ monitor...

Kind regards 

Tanja 

On 10 Apr 2021, at 7:41 PM, Søren Ugilt Larsen <sorenugi...@gmail.com> wrote:



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<Pastuerization temperature and PUs 03-04-2021.jpg>

[Søren Ugilt Larsen]

Hi Tanja,

I can recommend to read at least the first post by Andrew where the principles are explained:) 

I use a temperature logger similar to this one (very useful and at a reasonable price): Amazon.com: Inkbird Thermometer and Hygrometer Smart Sensor Data Logger with Waterproof External Probe Magnet Alert for Android and iOS Used for Food Storage Brewing Reptiles Instrument IBS-TH1: Home & Kitchen

And a thermostat controller like this to control the electric hob/stove: INKBIRD ITC-308 Termostat med controller (savdoktoren.dk)

After the pasteurization, I transfer the temperature data from the temperature logger to a computer, where I do the calculations in an Excel spreadsheet, using this formula: PU = minutes *10((Temp-60C)/7)

I have set the temperature logger to 10 second intervals, so I calculate the PUs obtained per time step and accumulate them over time. Of course, it would be convenient to get this calculation directly during the pasteurization in order to stop the process at the desired number of PUs.

Best wishes

Søren

[tanja s]

This is super helpful Soren! Thank you a lot!! 

Kind regards and greetings from Hong Kong:)

Tanja 

On 11 Apr 2021, at 4:51 AM, Søren Ugilt Larsen <sorenugi...@gmail.com> wrote:



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[gareth chapman]

I don't pasturise any of my cider but for my juice I just use a tried and tested method as established from previous recordings.
Related  but not exactly answering the question, I was reading a paper last year online (sorry can't seem to find it again), which concluded that as little as 1 PU was sufficient to prevent refermentation in wines

[tanja s]

Well, how about a hot climate (Hong Kong), when even during the coldest part of the year I had some ‘cider war’ incidents as my neighbors call it 😅

I don’t wish to use sulfite, sorbite, bensoate... And don’t really have huge cooing facilities. 

So I believe my only option is pausterization?

Thanks 🙏 

Kind regards 

Tanja 

On 12 Apr 2021, at 3:20 PM, gareth chapman <chappe...@gmail.com> wrote:

I don't pasturise any of my cider but for my juice I just use a tried and tested method as established from previous recordings.

To view this discussion on the web, visit https://groups.google.com/d/msgid/cider-workshop/e02bf0b0-03fd-4514-b293-6854398bd94en%40googlegroups.com.

[AW]

I think its even worse than you say - I've heard that some PU actually begin to accumulate between 50-60C.  

I think what you want to do is heat up your system to above 70C and then plunge in your wine.  The initial burst in temperature should carry the product up above 60C....whereas your's jumps to about 40C and then takes the better part of an hour to get up to temperature.  

[Dick Dunn]

(This was about in-bottle "pasteurization".)

I expect that plunging room-temp bottles into 70C water would be an
efficient way to break bottles! Beverage bottles are generally made to
withstand a fair bit of pressure, but not the thermal stress of a sudden
50 C difference between inside and outside of bottle.

However, I'll admit that I'm speculating. I haven't actually tried it,
because it sounds so likely to end badly.

On Sun, Apr 18, 2021 at 09:05:47AM -0700, AW wrote:
...

> I think what you want to do is heat up your system to above 70C and then
> plunge in your wine. The initial burst in temperature should carry the
> product up above 60C....whereas your's jumps to about 40C and then takes
> the better part of an hour to get up to temperature.

--
Dick Dunn rc...@talisman.com Hygiene, Colorado USA

[AW]

We don't start with 20C bottles Dick.   We start with 4C bottles and then equilibrate to about 35-40C first, in the range where zero PUs will accumulate.  At that step, you don't have to worry about timing so much.   

I use slightly thicker than average brown glass bottles.  I think they are rated to 4 volumes.  I've had a couple caps pop off but not a broken bottle.  I can't say I've done very many...maybe a few hundred.  

[David]

Plunging cold bottles in hot water doesn't break them. I have bath pasteurised hundreds of thousands over the years and plunging filled bottles that may only be a few degrees C into almost boiling water does not break the bottles. You may get an odd one now and then but if you examine the bottle you will nearly always find a fault in the glass.
I have no qualms about putting 4°C bottles into 80°C water, and I do mean just ordinary glass bottles.