Coopers Ox-bar PET bottles "better than glass bottles "

rubadub

What do you think of these?

http://www.homebrewwest.ie/coopers-ox-bar-24-500ml-pet-bottles-better-than-glass-bottles-837-p.asp

These new technology bottles consist of a layer of Ox-Bar sandwiched between two layers of PET plastic. This special Oxygen Barrier layer keeps CO2 in to preserve your home brew beer's carbonation, and it removes Oxygen from your beer . . . better than glass bottles because when you bottle your beer, it's inevitable that some air is introduced. These bottles drive the Oxygen in your beer through the Ox-Bar layer, resulting in a beer with less Oxygen, so it will stay fresher for longer. It's a chemistry thing, the oxygen molecules get pushed through the plastic and the Ox-Bar layer, but the CO2 molecules are too big to fit through. So, oxygen gets pushed out, and CO2 stays in!

I am guessing any old PET cap would fit them if you lost them.

EDIT: found some discussion here http://www.beoir.org/Community/viewtopic.php?f=23&t=3918&start=0

Donny5

I have a load of these. They do come with spare lids and any old coke lid will do, too. On the whole, I don't like them. I don't know why, as they are empirically better than glass, since:

1. They cool faster
2. THey are lighter
3. They are stronger and more resistance to breaking from over-carbonation
4. The lids blow off before the bottle bursts.

That said, glass just feels better, and once cold, it does keep the beer cooler. I also like popping bottle caps. Finally, the deal-breaker for me is that I wash my bottles in a dishwasher, and at 55C, the lowest my dishwasher goes, they deform.

rubadub

Good points, the lightness is a plus for me, I am not drinking much at home, and the though of lugging home empty swingtops would put me off. Being thinner walls they will be a slightly lower volume.

In the thread I linked there are valid points about oxygen being used up during bottle conditioning. The PET usually lets in oxygen afterwards which I presumed would also be used up by the yeast inside, and I found this.

http://forum.northernbrewer.com/viewtopic.php?f=1&t=36663&start=0

BOTTLES - PET vs. Glass

I have for several years used glass bottles with crown caps for my naturally conditioned sweet ciders (made by keeving) and recovered soft-drink PET bottles for my naturally conditioned dry ciders. Both seemed fine. But I'd never used PET for sweet naturally conditioned cider. I knew well from my professional life that PET bottles are gas permeable but I didn't anticipate any problem from that fact - they'd certainly always held the CO2 pressure very well.

In spring 2000, I had so much keeved cider that I was in urgent need of about 750 new litre bottles. .... I chose the PET bottles. .... I duly filled them with keeved cider at an SG of about 1.015 for natural conditioning. I also filled a much smaller number of regular crown-capped glass bottles with exactly the same cider.

After about a month (April 2000), the PET bottles had developed the normal turgor due to the internal pressure of naturally generated CO2. But when I came to tasting and comparing it with the glass, it seemed noticeably dryer and less well balanced than the glass-bottled version. At six months, the difference was extremely marked. All the PET bottles had become effectively naturally conditioned dry ciders, and only the glass bottles retained the naturally conditioned sweetness I was aiming at (and, incidentally, the subtle spicy bittersweet aroma character). The PET bottles also carried a much more pronounced yeast deposit and a greater degree of carbonation than in the glass. After nine months, the differences were still marked, but the PET ciders had begun to lose some carbonation perhaps due to diffusion. In some way they'd almost regained their balance, but it was a different balance from their glass contemporaries and without the complexity of flavour. And there was a slight hint of volatile acidity - not enough to be objectionable - but detectable all the same.

All these facts can I think be explained as follows:

PET is gas permeable while glass is not. This means that the yeast in the PET bottles can continue to draw in oxygen from outside, through the walls of the bottle, while simultaneously generating a positive pressure of CO2 inside the bottle. Hence the yeast in PET continues to metabolise the residual sugar by aerobic respiration during storage, leading to a dryer cider with a heavier yeast deposit.
.....

Although this is almost certainly true it's also counter-intuitive! Because the PET bottles develop a nice positive pressure of CO2 inside them, one then assumes that no other gas such as oxygen can diffuse back in. Unfortunately this simply isn't the case - the laws of physics here are all about partial pressures, and the partial pressure of oxygen is higher outside the bottle than in, so it can diffuse through. This is despite the fact that the partial pressure of another gas (CO2) is higher inside than out! Bizarre but it fits the facts.

.....

The 'take-home' message for craft cidermakers making sweet naturally conditioned ciders is simply that glass is the best. PET is OK, but it ain't so good!

Be warned!

So I wonder if the oxygen will get back in the ox-bar ones just as easily as the normal PET. Seems if might have been better if it was a oxygen and CO2 barrier!

Plastic beer bottles just seem wrong, probably just since they are not that popular so its sort of irrational (most have no real problems with plastic softdrink bottles), I have seen green plastic PET ones in tesco. Just like people do not accept cans of beer in pubs but happily drink them at home.

EDIT: found the beer I got in tesco, seems they do have a CO2 & oxygen proof layer. They were cheap in tesco when I got them, maybe €1 a pop, so are cheaper than empty oxbar ones!

http://www.thehomebrewforum.co.uk/viewtopic.php?f=23&t=13777&sid=

Something I've gone on about before and I'll go on about again is Martens Brewery, mainly because I've had a look around, guided by the boss himself. He's an existing Belgian brewery, and he's just built a totally new brewery and bottling plant. Can't remember the capacity, but from recollections of the dimensions of his fermenters it must have been at least 100 m3 per day, with a continuous flow three stage mash and sparge. Entire line controlled by 9 people in shifts, but that's another story.

The attached bottling line is fully PET. He inflates the bottles from blanks himself and then fills with acetylene and microwaves the bottles. This supposedly coats the inside in a layer of carbon impermeable to oxygen and CO2. It's doing well for him, he's got contracts to bottle other breweries beer from tankers, mainly for the events industry. Saw a very large pile of pallets in the warehouse branded up for shipping to Italy for football stadia (along with cans of mostly rice beer for parts of Asia where they levy tax on the malt content and not the alcohol :shock: ).

We've had a load of cases from him sat in our garage (out of sunlight) for a good few years now, and I've started reusing the bottles. The originals are all flat and oxidised to high heaven. They do take the pressure well to start with, but they're not good indefinitely. If you're bottling something for six months conditioning, go for it. If it's an Imperial Stout, I'd stick to glass.

They do have the advantage of being able to tell how well carbonated they are by squeezing.

Anybody know where to get it? not showing up on tescos site.

Donny5

rubadub wrote: »

EDIT: found the beer I got in tesco, seems they do have a CO2 & oxygen proof layer. They were cheap in tesco when I got them, maybe €1 a pop, so are cheaper than empty oxbar ones!

That is very interesting, but I do question your maths. The ox-bars you linked to are €12 for 24, so 50 cent each.

rubadub

Donny5 wrote: »

I do question your maths.

sorry! dunno how I missed that. Think I must have had 12 bottles in mind

Mr Benevolent

You can buy 500ml green plastic PET bottles in Tesco (with water in 'em). €1.65 for 6. Works fine for cider and way cheaper then the Coopers.

rubadub

Confab wrote: »

You can buy 500ml green plastic PET bottles in Tesco (with water in 'em). €1.65 for 6. Works fine for cider and way cheaper then the Coopers.

If getting water bottles it is best to get ones for fizzy water, as they are made to take the pressure. Many still water ones are thinner plastic and they do not have the cut threads on the lids. If you look at the lids there is a vertical cut which allows a slow release of gas when it is being unscrewed. Many still water bottles do not have this and the lid can fly off dangerously when opened under pressure.

Mr Benevolent

rubadub wrote: »

If getting water bottles it is best to get ones for fizzy water, as they are made to take the pressure. Many still water ones are thinner plastic and they do not have the cut threads on the lids. If you look at the lids there is a vertical cut which allows a slow release of gas when it is being unscrewed. Many still water bottles do not have this and the lid can fly off dangerously when opened under pressure.

I should've mentioned that these bottles are for carbonated water.