Cans keep out oxygen, so they say. Bottle tops don't do quite such a good job, so we are told. It's all to do with the seal that can be achieved. Oxygen can sneak through the tiny molecular gap that might be present between glass and the plastic seal on a cap. Metal to metal is a far tighter closure, apparently.
That is all well and good, but is it possible to get beer into the can reliably without oxygen pick-up? As it happens, Stonch has already cast doubt on that. I can't really be sure, except for the fact that the canning lines I have seen seem to not have all that a reliable way of purging with CO2 and there is certainly no pre-evacuation of the can.
However, our bottling line at Hardknott is the double pre-evac counter pressure filling type machine. What this means is that a contraption attaches to the bottle neck sealing hermetically from the atmosphere. Most of the air1 is pumped out. The bottle is then filled with CO2 at a pressure of 1 atmosphere gauge pressure2, i.e. 2 atmospheres absolute. This process is then repeated again, hence the word "double" in the name.
Only then is the beer allowed to flow into the bottle, under a counter pressure of more CO2 at around 2 bar. When the beer goes into the bottle it is extremely oxygen free. When the pressure is released the beer fobs a little, and we set the rate of bottling to get the right fobbing, along with a little squirt of sterile water to help it foam. This fob is all beer and CO2 with only a tiny area exposed to the air.
The canning lines I have seen try to puff out the air with a little tube that goes to the bottom of the can. The beer is filled from the bottom of the can to try and push the CO2/air mixture of unknown purity out of the can. Any fob will have quite a significant area in contact with the air.
In my view to can reliably with low levels of oxygen it would be necessary to do the process in a blanket of CO2, rather than the open systems I've seen.
Cans might keep out oxygen, but I'm fairly sure it is a lot harder to stop it being in there in the first place. The filling process is certainly not as hermetic as with our bottling line.
Because it is difficult to explain in words I did a little animation for our bottling line.
Top from Hardknott Brewery on Vimeo.
Incidentally, I hadn't really thought about the problems of canning compared to bottling until Jon from Stringers pointed it out to me the other day. All the result of a chat over a beer. Isn't beer good.
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1Our vacuum pump gets down to about 0.1 atmosphere absolute pressure.
2Gauge pressure is the pressure relative to the atmosphere.
Showing posts with label canning. Show all posts
Showing posts with label canning. Show all posts
Thursday, 2 June 2016
Tuesday, 27 January 2015
Metalman in a metal can
When the whole talk of craft beer in a can started, a few years ago, I honestly thought it wouldn't take off. It's just crude to serve beer from a can. Uncouth. Totally unrefined and certainly not the thing that a respectable craft brewer would promote.
Well, it turns out I was wrong. My first realisation came about when I was having a bit of a twitter rant about the subject when well respected brewer type from NZ, Kelly Ryan, listed a few plus points of the format. It seems that oxygen take-up is much lower, headspace less, weight of the packaged product certainly lower per ml and metal cans significantly more recyclable than glass. I remember the put-down quite clearly. "there you go Dave, made a dumb-ass out of yourself again" I thought.
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Last year we went over to Ireland and brewed with Metalman. Great fun was had making Yerba and Ireland is such a lovely place. The folks in Waterford are grand, too.
I remember Gráinne and Tim were looking at canning, and had already made up their minds back then to by-pass completely the idea of packaging into bottle. I have been watching their progress, quietly from a distance, it has to be said with a little bit of envy. I learn today that they have finally got their machine installed and are pushing out cans of their fine Pale Ale.
I still have a few concerns. The whole business of ensuring a gas tight seal, and the fact that the beer surface is so much larger before sealing than with bottle worries me. It doesn't quite stack up in my mind that the risk of oxygen take-up is actually less. I am left to assume that the real danger is from gas diffusion through the seal. In bottles there is a hard and inflexible surface of the glass against which a plastic seal is forced. The seal isn't perfect and despite the CO2 being at pressure there is still a movement of oxygen molecules which are smaller than carbon dioxide molecules. (32 grams per mole, compared to 44). The crimped metal to metal surfaces once must assume are a much tighter seal.
There are other problems, which I wonder how canning brewers manage. For a start, we get between a few hundred and 20,000 labels printed at a time. We get 18,050 bottles delivered per order. We do have to buy branded caps in lots of 110,000 (Next up it's green for us) - but we don't have to have huge stocks of very much.
Cans, now, as best I can tell they are printed in lots of at least 100,000 at a time. That is a shit-load. I know what 18,050 glass bottles look like. 5-6 times that is going to need a big warehouse, and that would be for each and every product. At least we don't have to buy our bottles with the label already on them. We're bottling tomorrow, I will probably decide which beer when I get in to the brewery, safe in the knowledge that the bottles don't care. It only takes a few minutes of swearing to get the labelling machine to work properly.
And then there is the little nightmare of paying for the damn things. Cash-flow, it's a real bastard, really it is. Just in time is the way forward, not having a great big warehouse.
However, as a firm convert to the idea of microbreweries pushing out keg, with various advantages, why should any format be the preserve of big breweries? If cans provide a route to market for smaller breweries then why shouldn't we have a slice of that particular cake?
Cans are indeed light. Around 30% of the weight of our bottles is glass. This becomes significant when considering transport. Whether posting our from our webshop, of for that matter any of the on-line places you can get our beer, there are weight restrictions that impact on the costs of getting it to the customer. We can only put a maximum of 1,200kg on a pallet. If a third is glass there is less room for beer.
The recycling thing is much more important though. Metal is relatively easy to recycle. Cans can easily be sorted into aluminium and ferrous with simple magnetism. They can be crushed and transported in an economic form.
Glass is harder to sort. Apparently there is technology that can deal with it, but one can assume this has to be done before any crushing occurs. For certain it's much more complex than just waving a magnet next to the stuff. The nearest place to Cumbria that can automatically sort glass I believe is in Liverpool.
We have to pay about the same to send any waste glass into re-cycling as we do sending it into the land-fill route. At the other end I am told by our glass supplier that they cannot get enough waste re-cyclable glass. My local re-cycling entrepreneur tells me it is the transport that kills the economics. All down to weight again, you see.
So, is Hardknott going to start canning? I know Thornbridge have decided to stear clear for now. I'm keeping an open mind, although more and more these days, on a whole range of subjects, it seems this is the best strategy, at least up until the point of saying "yes".
Well, it turns out I was wrong. My first realisation came about when I was having a bit of a twitter rant about the subject when well respected brewer type from NZ, Kelly Ryan, listed a few plus points of the format. It seems that oxygen take-up is much lower, headspace less, weight of the packaged product certainly lower per ml and metal cans significantly more recyclable than glass. I remember the put-down quite clearly. "there you go Dave, made a dumb-ass out of yourself again" I thought.
Last year we went over to Ireland and brewed with Metalman. Great fun was had making Yerba and Ireland is such a lovely place. The folks in Waterford are grand, too.I remember Gráinne and Tim were looking at canning, and had already made up their minds back then to by-pass completely the idea of packaging into bottle. I have been watching their progress, quietly from a distance, it has to be said with a little bit of envy. I learn today that they have finally got their machine installed and are pushing out cans of their fine Pale Ale.
I still have a few concerns. The whole business of ensuring a gas tight seal, and the fact that the beer surface is so much larger before sealing than with bottle worries me. It doesn't quite stack up in my mind that the risk of oxygen take-up is actually less. I am left to assume that the real danger is from gas diffusion through the seal. In bottles there is a hard and inflexible surface of the glass against which a plastic seal is forced. The seal isn't perfect and despite the CO2 being at pressure there is still a movement of oxygen molecules which are smaller than carbon dioxide molecules. (32 grams per mole, compared to 44). The crimped metal to metal surfaces once must assume are a much tighter seal.
There are other problems, which I wonder how canning brewers manage. For a start, we get between a few hundred and 20,000 labels printed at a time. We get 18,050 bottles delivered per order. We do have to buy branded caps in lots of 110,000 (Next up it's green for us) - but we don't have to have huge stocks of very much.
Cans, now, as best I can tell they are printed in lots of at least 100,000 at a time. That is a shit-load. I know what 18,050 glass bottles look like. 5-6 times that is going to need a big warehouse, and that would be for each and every product. At least we don't have to buy our bottles with the label already on them. We're bottling tomorrow, I will probably decide which beer when I get in to the brewery, safe in the knowledge that the bottles don't care. It only takes a few minutes of swearing to get the labelling machine to work properly.
And then there is the little nightmare of paying for the damn things. Cash-flow, it's a real bastard, really it is. Just in time is the way forward, not having a great big warehouse.
However, as a firm convert to the idea of microbreweries pushing out keg, with various advantages, why should any format be the preserve of big breweries? If cans provide a route to market for smaller breweries then why shouldn't we have a slice of that particular cake?
Cans are indeed light. Around 30% of the weight of our bottles is glass. This becomes significant when considering transport. Whether posting our from our webshop, of for that matter any of the on-line places you can get our beer, there are weight restrictions that impact on the costs of getting it to the customer. We can only put a maximum of 1,200kg on a pallet. If a third is glass there is less room for beer.
The recycling thing is much more important though. Metal is relatively easy to recycle. Cans can easily be sorted into aluminium and ferrous with simple magnetism. They can be crushed and transported in an economic form.
Glass is harder to sort. Apparently there is technology that can deal with it, but one can assume this has to be done before any crushing occurs. For certain it's much more complex than just waving a magnet next to the stuff. The nearest place to Cumbria that can automatically sort glass I believe is in Liverpool.
We have to pay about the same to send any waste glass into re-cycling as we do sending it into the land-fill route. At the other end I am told by our glass supplier that they cannot get enough waste re-cyclable glass. My local re-cycling entrepreneur tells me it is the transport that kills the economics. All down to weight again, you see.
So, is Hardknott going to start canning? I know Thornbridge have decided to stear clear for now. I'm keeping an open mind, although more and more these days, on a whole range of subjects, it seems this is the best strategy, at least up until the point of saying "yes".
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