Poor Canning Practices or a Fridge on the Ropes?

Been thinking more about this...this is acutually an interetsing problem with multiple explanations. First, it is still possible for a can to expand permanently upon freezing and then collapse (dent) to accommodate the volume change of the beer as it thaws. That would be exacerbated by an overfill since there is less headspace in the can to accommodate expansion of the beer as it freezes (* note that water actually begins to expand at temperatures of about 39 deg F and lower...it does not have to get all the way to freezing to grow in volume, although the phase change upon freezing is by far a bigger volume change). There is a fine line between can expansion upon freezing and can rupture and that fine line is related to the volume of the beer vs. volume of air in the can. At the right ratio the can can grow a little to accommodate the beer expansion and then shrink to original dimensions (i.e. the yield strength of the aluminum is not exceeded by the force of the expanded ice). At more beer/less air, the can can be stressed beyond the yield point and the can will be slightly permanently enlarged, but not failed. This could resulting in the sides of the can getting sucked in when the beer thaws and contracts. At even more beer/less air, the expansion upon conversion to ice could stress the aluminum to the ultimate tensile strength and break the can.

An underfill could also be a problem because the coefficient of thermal expansion for air is roughly 16x that of water at room temp, so if you have a lot more vapor space in the can, it will be more likely to contract more upon cooling in the fridge since the total air+beer volume will change a lot more than when the volume is almost all beer.

The denting cannot be related to a leak because a leak allows pressure to equalize so there is no driving force for the mechanical deformation that was illustrated, unless someone shoves a food container up against the can in the fridge. Even then, the symmetry of the denting in the photo does not look like mechanical denting from an outside force like a food container. It looks a lot more like a pressure differential (inside can v. outside of can) related to a volume change resulting from temperature change.

 

You can easily illustrate the conceptual effect of underfill on susceptibility to the can denting when chilled to normal temperatures. Take three 1 pint plastic water bottles at room temperature with screw-on caps. Take bottle one and fill to the top with water except for maybe 1/4 inch head space of air. Replace cap. Take bottle two and dump some water out leaving about 1/3 the bottle or more with air. Replace cap. Take bottle 3 and fill with water and leave the cap off to simulate a "leaking can". Put all three in the fridge. A few hours later check the bottles after they are cold. The bottle without cap will be unchanged. The bottle with the least water will be the most "sucked in". The bottle nearly full of water will have only a small amount of contraction.

 

Regarding the freeze/thaw theory.
I've accidentally left 6 packs in my car during single digit & sub-zero temps. My experience has been burst seams or pull tabs, I've never had a frozen solid can collapse when it thawed.

 

Yep, when they freeze they burst outward, as my wife reminds me every time I fall asleep and leave beer in the freezer.

 

My extra fridge will occasionally freeze a beer that is in the very back where the air enters. I have never had it concave a can, upon freezing it will usually deform the top and push outwards, along with the bottom. So if you are not seeing that on this can, it is probably a short fill

 

If there was a full can there would have been liquid inside to push back.

 

When a can freezes all the way, at some point it usually bursts the lid or the seams and the party is over. Sometimes though, it can stretch things out a bit without actually popping the seams before it melts again. There’s then empty space in the now “stretched” can that atmospheric pressure can push inwards.

To find out if this is what happened to the OP, they can simply pour it into a glass or measuring cup and see if they have 16 ounces of liquid or not. If not, and there’s no signs of leakage anywhere, it was clearly a short fill.

 

If the OP already drank or poured out the beer, but still has the can, they can fill it with water and then pour that water into a measuring cup or pint glass. If anything over 16 fluid ounces, that’s also a sign that the can was stretched. (From the photo, the top of the can looks pretty intact — possibly because a plastic holder was on it — so this little experiment should be relatively easy.)

 

Maybe so, but in all my many years of freezing and falling asleep ruining beers they all burst out. I’ve never had one suck it in, sounds like it’s been a problem for him. Could it be the local mobile canner screwing it up? I’ve never had a short fill beer, ever, I’m sure they exist but it’s nothing I’ve ever experienced.

 

Like I said, pretty easy for the OP to figure out which problem it was if they still have the can handy. There’s either 16 ounces of beer there or not.

FWIW, beers I’ve accidentally frozen from sticking in the freezer too long have all exploded outward. Once I had a beer that was in the back of the fridge, tough, and when I pulled it out it was all soft and squishy like the OP’s. I was convinced it was a short fill, but when I poured it into a glass, it was a full 16-ounces. Someone told me then about the freeze and thaw theory, and I’m convinced that’s what happened.

 

Agreed on all accounts. But whether it’s an issue with the cans themselves or the canning process, it’s still a problem

 

I see this happen all the time at work. Cans are either empty or under filled.

 

Sometimes you get a wonderful beer slushie.

 

I think this is more correlation than causation.

I think, coincident with the to canning, has also been a shift toward beers that are more susceptible 'damage' during packaging. In particular, very heavily hopped IPAs, and even more so, the recent trend of NEIPA. Hops are very susceptible to oxidization, and it seems the increased protein content in NEIPAs also lends itself to oxidization.

These are problems you'll run into, potentially, on any packaged beer no matter the vessel, if the brewer isn't closely monitoring quality control.

That said, yes, this particular shrunken-can-low-fill issue wouldn't occur in a bottle. You'd just have a low-filled bottle of beer.