PET Bottles - How long is too long in the bottle?

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idzy

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Hi Guys,

I have a particular PET peev at the moment regarding the so called pourous qualities of plastic bottles, cubes and fermenters. For this thread, the discussion is PET bottles as it seems there has been some recent talk on it.

Questions to be answered:
Does PET cause oxidisation in beer over an extended period of time? AHB Posts say yes.
Does PET cause loss of carbonation over an extended period time? AHB Posts say yes.
What is the recommended time for PET bottle storage and consumption?
And finally, but most importantly, has anyone actually tested this, or is based on the difference in the chemical properties/make up comparable to glass?

Scientific tests, specific to PET bottles used for home brewing and or anecdotal observations are welcome. Theories have been done to death...botulism anyone?



Okay there, I said it.
 
Your best bet might be to email Coopers and ask, I doubt if anybody else actually knows but you get plenty of anecdotes and guesses here.


Atb. Aamcle
 
Regarding the longevity of PET bottles and the loss of carbonation, the question was raised in the Coopers homebrew forum back in 2008.

A reply was posted by PB2 who is a Coopers employee.

Here's what he said:

Their longevity depends, partly, on the way they are treated.

If they keep holding pressure and don't delaminate they will be good to keep using for your beer.

Tests, run at the brewery, had a few PETs going for 13 different batches, others primed with 4 and 6 carbo drops for pressure testing, while others were used over a period of 4 years without any failures!

They tend to lose pressure if holding a brew for 18 - 24 mths so we don't recommend them for storing big beers that you hope to age over a couple of years (use sturdy glass bottles or kegs instead).

I have to admit, after 13 brews and 4 years, I got a bit bored with the whole thing and dropped the PET testing program - had a lot more interesting projects to run. :D


https://www.coopers.com.au/coopers-forum/topic/6811/
 
Thanks Felton, pretty informative.
 
mofox1 said:
Delaminate?
I think I read somewhere that there is an internal nylon lining which can separate from the PET shell.

More likely to happen if you clean them with very hot water.
 
idzy said:
Hi Guys,
...
Does PET cause loss of carbonation over an extended period time? AHB Posts say yes.
...
5 6 year old Coopers Lager in a PET bottle ... yes, I think it's lost a bit of carbonation :lol:

PET_5yrs.JPG
 
MaltyHops said:
5 6 year old Coopers Lager in a PET bottle ... yes, I think it's lost a bit of carbonation :lol:
Give it a good shake, that'll bring some life back into it!
 
I have found that the flavour seems to change after too long in a PET bottle. I usually max out at 6 months. Although the Brown coopers bottles are a lot better than the clear soft drink bottles (3 months)
 
Definitely no good for long term storage. I forgot a few and they are very flat.

I don't feel PET allows more O2 ingress, but nor does it exclude the beer from oxidation.

Very suitable for mailing beer to people. Lighter and more resilient than glass.
 
My father used to use PET bottles... still does when he's planning a big motorhoming expedition.

We found that most of his beers were objectionably flat after 6 months.

Thus a large part of convincing him to migrate to glass ;)
 

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