Plastic coopers brown bottles , **** ?

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I was considering a beer gun or counterpressure filler but the ease of filling those plastic bottles with a £10 piece of kit has made me stop and think a bit more.

 

[Nicky P]

@Scott Begbie and @Slid
Thanks for the comments! The bottles were being stored empty without tops at a temp of around 20C in a kitchen cupboard, kept there until I had enough to start a new batch. I then sanitised with Harris no rinse sanitiser in tap water at around 10C. They were then left draining in the dishwasher until I rinsed them all later with fresh cold water (can't get used to no-rinse). It was soon after that I heard the cracks. Perhaps it was the quick change of temps from 20C to 10C and back to 20C a couple of times that did it! The tops were still not on at the time.

 

[Slid]

@Scott Begbie and @Slid
Thanks for the comments! The bottles were being stored empty without tops at a temp of around 20C in a kitchen cupboard, kept there until I had enough to start a new batch. I then sanitised with Harris no rinse sanitiser in tap water at around 10C. They were then left draining in the dishwasher until I rinsed them all later with fresh cold water (can't get used to no-rinse). It was soon after that I heard the cracks. Perhaps it was the quick change of temps from 20C to 10C and back to 20C a couple of times that did it! The tops were still not on at the time.

No, if the tops were off, my explanation is not the cause.

 

[Fred mercuree]

I only started brewing again in February this year after an absence of 30+ years.
Not sure if I was going to get serious again, I wasn't going to spend a lot at first. So I have been using 1 litre PET bottles that my wife had Tonic Water/Soda Water and Sparkling Water in and they have been outstanding. Beer tastes great and when they have hardened, I know they have carbonated well. They have been used several times now and really, I can't see a reason NOT to use them. I must have about 70 in the garage now, all with different brews in them. I believe I am now getting serious ......

Good tip mate blimey your missus can sup some tonic water how much gin to go with it? Lol

 

[Fred mercuree]

My opinions on using PET bottles for homebrew packaging are well documented elsewhere on this forum, so I won't bother to repeat them here. However, I worked in the plastics industry for most of my working life, and I know quite a lot about the various processes for making plastic bottles.
PET bottles for carbonated drinks are normally made in a two stage process:

• First of all the PET polymer is injection moulded into "preforms" in multi-cavity moulding tools. They looks like a thick walled test tubes with a threaded top. They take up very little space (compared with a finished bottle) so are easy to store and to transport.
• The second stage is to blow the bottles. This is done by reheating the preforms to a point where the PET is softened and malleable, but not fully melted. The heated preforms are then transferred to the bottle moulds where they are stretched both axially and longitudinally using a mechanical plunger and high pressure air, The PET is now in direct contact with the inside of the moulds, and is rapidly cooled to fix the shape and dimensions before being ejected from the mould. see:

This final biaxial orientation process alters the properties of the PET. It makes the bottles very tough, and it also improves the gas barrier properties, particularly to CO2. The bottles are not actually laminated during production, but they are often coated to improve the oxygen barrier properties and shelf life when the intended use of the bottles is for packaging oxygen sensitive products. The application of barrier coatings is quite a costly process, so this is only done when necessary, e.g. mineral water bottle would not normally be coated.

I have just started brewing and use the plastic pet caps that look and feel good quality, any tips on using them like washing after use and storing ready for the next time?

 

[Hop_it]

I have just started brewing and use the plastic pet caps that look and feel good quality, any tips on using them like washing after use and storing ready for the next time?

I'm not sure what kind of caps you are referring to . . . . . . But if you mean the screw-on caps used on the vast majority of PET drinks bottles, then they are made from HDPE (high density polyethylene). This is a durable material with good chemical resistance. You can wash them in standard household detergents, and sanitise them with any of the proprietary products sold for homebrew use. Just make sure that they are thoroughly dry before putting them away. The only problem you might encounter is that the seals will deteriorate over time with repeated use, and a small amount of stretching due to creep.
If you are using the "Coopers" types bottles then I have no idea what their caps are made from because I have never handled them nor used them myself. However, they are designed for repeated use, so I would imagine that the caps can be washed and sanitised in much the same way as the disposable PET drinks bottle caps, but the same warning applies concerning gradual deterioration of the seals.

 

[Fred mercuree]

I'm not sure what kind of caps you are referring to . . . . . . But if you mean the screw-on caps used on the vast majority of PET drinks bottles, then they are made from HDPE (high density polyethylene). This is a durable material with good chemical resistance. You can wash them in standard household detergents, and sanitise them with any of the proprietary products sold for homebrew use. Just make sure that they are thoroughly dry before putting them away. The only problem you might encounter is that the seals will deteriorate over time with repeated use, and a small amount of stretching due to creep.
If you are using the "Coopers" types bottles then I have no idea what their caps are made from because I have never handled them nor used them myself. However, they are designed for repeated use, so I would imagine that the caps can be washed and sanitised in much the same way as the disposable PET drinks bottle caps, but the same warning applies concerning gradual deterioration of the seals.

I'm using the easy brew 500ml amber bottles and find them good quality and well made..

 

[GhostShip]

I've been involved in a number of beer swaps and interclub competitions over the last nine months where beer has been exchanged in bulk and what has been oh so apparent is the variation in beer quality when a batch of beer has been provided in PET bottles (both of the Coopers type and the type pictured two posts up).

It has happened so often now that it cannot be a coincidence....some folks will receive a beer that is very drinkable with no obvious issues, others will receive exactly the same beer bottled at exactly the same time that has spoiled in some way. Its not down to the individuals storage of the beer as its been known for more than one person to have an issue. There may be times when poor (not well tightened) capping may be to blame but on other occasions bottles are received with well tightened caps.

The same issues are not observed at all with glass crown capped bottles.

The experiences have put enough doubt in my mind that I will no longer submit beer for comps in PET bottles and my only use of PET will be the three bottles I use in each batch to monitor carbonation in the bottle.

I’m not for one minute disputing your experience, but how can a product (PET) used through the food and drink industry worldwide, cause off-flavours in beer?

 

[JockyBrewer]

I’m not for one minute disputing your experience, but how can a product (PET) used through the food and drink industry worldwide, cause off-flavours in beer?

Well I'll say for a start that PET is not used for beer globally. I've had some plastic bottled beer at football matches, but the bottles do seem to be thicker plastic in that case.

I agree with Nick that the results from PET bottles have been highly varied in the swaps that have gone on between homebrew clubs. From my point of view there seems to be a couple of culprits:
1. Lids are not always tightened enough. Noticeable when you get a somewhat flat, oxidised beer.
2. Not all PET bottles are the same. The Coopers ones seem ok. But there's some cheaper ones, as shown in the photo here, that seem to consistently produce oxidised beer. I don't know why.

View attachment 48373

3. The lids on all PET bottles don't seem to have a liner, or if they do it's not as effective as a crown cap oxygen scavenging liner. I proved this to myself recently by bottling into PET and glass bottles using counter pressure fillers, then left it two weeks before sampling. The PET bottles were a tiny bit darker (only apparent in good light) and the fresh fruit I got from the hops in the glass bottle had gone a bit overripe.


Having said that, I do like the PET bottles because they're almost indestructible for shipping. I need to do some more experiments with them to get a result as good as bottling into crown capped glass, but best practice for me at the moment would be:

1. Buy Coopers bottles.
2. Fill to a small headspace (1cm) and after filling the squeeze out the rest of the air in the headspace before capping.
3. After filling all your bottles, get a tea towel and check the lids are tight.

 

[Begbie]

2. Not all PET bottles are the same. The Coopers ones seem ok. But there's some cheaper ones, as shown in the photo here, that seem to consistently produce oxidised beer. I don't know why.

I don't know why either. I've never had an oxidised beer/mead/cider since I started brewing 2 years ago, and using these bottles. I do screw the lids on tight mind you, but not tea-towel-tight. Is it possible that during transportation, some beers 'spoil' with being shaken up during its journey, especially if they had 4 or 5cm of headspace?

I don't squeeze the bottles after filling either - I fill to the neck or just above, withdraw the bottling wand, leaving about 4cm of head space and put the lid on.

 

[Hop_it]

I’m not for one minute disputing your experience, but how can a product (PET) used through the food and drink industry worldwide, cause off-flavours in beer?

You are correct. The PET polymer used for beverage bottles (and many other food packaging applications) is not the direct cause of "off flavours". It is chemically inert to anything that you will find in the food and drinks industry, e.g. sugary drinks, alcoholic drinks, and oils and fats. This issue was researched very thoroughly in the early days of PET bottles when producers of mineral water started to use them. Mineral water is particularly sensitive to taste and taint from the packaging. A lot of work went into ensuring that the PET bottles were "taint free".
So, any problems that may occur when homebrew is packaged in PET bottles (whatever their source) is down to something else, e.g. oxidation from the head space or from oxygen permeability through the wall of the bottles or poorly sealed caps, or possibly from being light struck, or any number of things that your average homebrewer cannot control.

 

[nickjdavis]

I’m not for one minute disputing your experience, but how can a product (PET) used through the food and drink industry worldwide, cause off-flavours in beer?

I never said the PET bottles themselves caused the off-flavours.

However, beer is far more susceptible to imperfections in its environment within a PET bottle than the drinks that you would typically find packaged in such bottles....so things like Oxygen permeability, poor capping, poor quality O2 scavenging caps, variable quality of the bottles themselves etc. will all have a potential greater effect on the long term quality of the beer than they would on say coke or lemonade.