bottles for heat pasteurization?

[mattrix]

Sorry if this has been answered somewhere.

I've got some scavenged bottles, but they are all twist tops.

I'd rather get a fizzer than a glass "bottle bomb".
Looking at the brew shops,

PET bottles are easy to get. Will they will take the pressures involved?

Alternatively I can get Grolsch bottles with the swing top caps. I have read that these leak at 70psi while other sources say they won't leak until pressure is greater than 150psi. Are these suitable, better than PET?

Or should I go to the extra effort to get crown seal bottles?

thanks for any advise.

 

[Chalkyt]

I use salvaged crown seal bottles, but in the past have used salvaged twist tops without any issues. However, I understand that twist tops can be weaker than regular crown seal bottles. I also understand that PET bottles can suffer from gas transfer issues and so are not recommended for long term storage.

A local supplier rates their bottles at not being suitable for more than 4 gv (gas volumes) or 60 psi. Having said that, a major global manufacturer (China Misa Glass) claim that their product meets GB4544 (a Chinese Standard) which requires beer bottles to withstand 1.2 MPa or 175 psi (recycled bottles are discounted by 25% to 130psi).

In practice I heat pasteurise carbonated cider in recycled crown sealed bottles to 65C, which means that the internal bottle pressure can approach 90 psi for a short time. This seems to be a reasonable safety margin to me. I don't get bottle bombs unless I do something silly like exceeding 2.5 volumes of CO2 or letting the temperature get too high. If going down this path, PPE is essential, "just in case".

The point of this is that recycled crown seal bottles can be O.K. (and I suppose twist-tops too) if you know what you are doing and don't let the pressure get too high. Others might have different views.

Make your own judgement.

Cheers!

 

[Chalkyt]

This is a bit of a P.S. to the previous post. If you use PET bottles with depressed bottoms they may "blow out" under pressure (i.e. become round at the bottom) causing the bottles to fall over and become difficult to retrieve without cooking your fingers... Don't ask how I know!!!!

 

[mattrix]

Thanks Chalky,
I don't expect bottle bombs, my point was that PET and Grolsch bottles have an extra degree of safety. PET because, well, they are not glass; and Grolsch in theory the seal will give in before the bottle explodes. If the seal fails at 100+psi then there is still that much pressure in the bottle, so you don't lose carbonation.

I think I read that at one stage you used to use Grolsch bottles. Did you scrap them because they were unreliable?

As to crown seals, I have heard of twist caps exploding from normal carbonation, and once one goes the flying glass causes a chain reaction. To get 90psi at 30C, it would require 5 volumes of CO2 (If my math is correct). Which seems unlikely, so I'd rather not over-pressurize twist tops.
However I have found scavenged crown seals are difficult to find, so I'll probably be buying them anyway.

I think I'd prefer Golsch if they will do the job.

Just my thoughts, though I don't have any experience, but I do have all my fingers..

 

[Miraculix]

I've used flip top and crown cap bottles, never had a bomb but had some cracked bottles at the beginning. I can tell from experience that there's usually a little bit of foam escaping from the flip top ones, so these seem to have a bit of a"safety valve" on top of it.

I'd never do this with pet. You don't know what's leaking into your liquid out of the plastic at higher temperatures. It's also permeable for oxygen so I would skip it here. There are good uses for pet bottles in brewing, but this one is not one of them if you ask me.

 

[mattrix]

Off Topic: has anyone tried cold pasteurization?

A 3 vol CO2 bottle @ 0C is about 12psi.
Then open the bottle add sweet and preservative, seal again.
When it gets to 25C, it will still have about 30psi.

I know, chemicals. Just a thought.

 

[mattrix]

I can tell [you] from experience that there's usually a little bit of foam escaping from the flip top ones

But, was it still sufficiently carbonated, when you opened it?

 

[Chalkyt]

Re the Grolsch bottles. I don't use them for sweet-carbonated cider (i.e. hot water bath pateurised) because they do leak at around 70psi and peak pressure can exceed this (and the actual Grolsch bottles are hard to put labels on), but I do use other plain ones with similar seals for fully fermented ciders carbonated to 2.5 volumes (around 45psi).

Fortunately, I have a good source of 330ml crown seal bottles (from a thirsty sporting group I belong to, of course!).

Your pressure calculation is correct. FYI Andrew Lea has an excellent downloadable Excel Carbonation Table based on Henry's Law (just plug-in the volumes of CO2 and it calculates the pressure for a given temperature). You should be able to find it via his web-site cider.org.uk, by Googling "Andrew Lea Carbonation Table" or http://cider.org.uk/carbonation_table.xls

Re the leaking seals, have a look at a post by Beaudoin 9 April 2013 where Grolsch acknowledge this. Also, in his chapter on Ice Cider, Jolicoeur says "these will let excess pressure exit and thus avoid bursting".

 

[Miraculix]

But, was it still sufficiently carbonated, when you opened it?

Yes. The amount of lost carbonation was not detectable.