The shock of the new

Matt Curtis looks into the poorly-understood phenomenon of ‘can shock’ and why ultra-fresh packaged beers may not always be the best


Like many of you reading this, I’ve spent much of the past 15 months sat at home on my sofa, attempting to stave off existential dread, often while enjoying a can or two of delicious beer. As the grip of the pandemic tightened in early 2020 and our beloved pubs and bars were forced to close for our own safety, breweries had to pivot away from the usually reliable outlets that sold their beer on draught. Cans and bottles became the norm—in fact I can imagine it was probably a good time to be in business if you sold canning equipment for a living. 

In addition to this move to smaller containers, many breweries started selling direct to consumers via their websites. This was an incredibly fortuitous turn of events for the newly-at-home drinker, allowing them to order brewery fresh beer—sometimes even before it had been packaged—delivered to their door within 24 hours. I too indulged in this, often delighting when beer arrived at my doorstep and seeing it had been filled only the day before when checking the date stamp on the base of the can. 

But this wasn’t all good news. In my eagerness I would often open a can or two the same day they arrived, and on occasion I found the beers within to be off balance, with flavours spiking out in all different directions meaning the beer was unable to provide the level of satisfaction I typically expect. Normally reliable IPAs and lagers would lack that blissful balance between malt and hop, with these flavours either tasting muted, or one completely dominating the other. For some reason as yet unknown to me even the reliable beers I drank regularly didn’t quite taste right when drunk within hours of being canned and shipped, and I’ve been investigating why this is ever since. 

Thankfully, in terms of my diligent research, another habit of mine to have emerged in lockdown is that I began regularly purchasing multiples of the same beer rather than just one-offs. Often four or six of the same can would sit at the back of my fridge, waiting for the call of the weekend (or a particularly mundane lockdown weekday evening.) With some time to settle after a few days or weeks, the beers changed into something more familiar. With time and stillness, the flavours became integrated, balanced and far more enjoyable. 

This began to happen so often that I decided to speak to brewers about it. And while some denied it was something they had experienced, others said they found it to be a common phenomenon, and referred to it as can, or bottle shock. The idea being that the very process of packaging and shipping beer can cause its flavours to destabilise—albeit temporarily—and that giving them time to properly rest before serving is what’s required for maximum enjoyment. Some even took this view further, admitting that their beer didn’t taste quite how they wanted until several weeks after it’s packaged.

“Our beers always seem to taste better with a bit of maturity,” Yeastie Boys founder Stu McKinlay tells me. “They’re like awkward teenagers to begin with. I always think they’re at their best between one to three months of age.”

Stu founded his brewery in New Zealand in 2008 before relocating to the UK in 2015 where its beers are currently brewed under license at Devon’s Utopian Brewery. For a long time he’s taken the stance that his beers taste better with a little age on them. But he is still an advocate for fresh beer, and when he talks about his product this way he means beer that has been properly stored in cold, dry conditions. Like me, Stu also believes that his beer doesn’t taste its best immediately after packaging, referring to how pushing ready to can beer through numerous pumps and hose pipes with carbon dioxide is going to have a detrimental effect to how it tastes — at least temporarily. 

“Think about how you feel when you go through security at an airport,” he tells me. “You’re completely different when you come out of the other side.”

Stu also talks about how he doesn’t necessarily believe the “fresh is best” mantra pushed by a lot of breweries always presents these beers in their best possible light. While it is indeed true that beers are sensitive and flavours fade, particularly in terms of dry-hopped beers, which are packed full of delicate oils that rapidly evaporate when exposed to heat or light, I was interested in getting to the bottom of why exactly the beers I’ve been drinking taste out of whack soon after canning. 

In terms of breweries pushing freshness as hard as they can, Stu thinks it’s something of a marketing ploy to help breweries turn beer over faster, and create a little extra excitement in the customer as a result. Still, we both agreed that even modern, heavily hopped styles of beer tend to taste better three or four weeks after they’ve been put into a can.

Packing and immediately shipping beer is having a short-term negative effect on its flavour

When I talk about “can shock” however, I’m not talking about very hoppy beers which taste “green” when they’re new due to the high volume of hops used in their production. This can often present itself as a grassy character, with some fresh beers even leaving a slightly burning sensation (literally called “hop burn”) at the back of the throat. I consider this a brewing fault—beer should never taste of burning. What I mean in terms of can shock is beers that taste unbalanced, out of whack, their flavours temporarily destabilized due to the beer having been aggressively moved around. 

“I’ve experienced the phenomena with pretty much every beer I’ve packed since joining the industry,” Zoe Wyeth, a production brewer at Villages in South London, and previously for Suffolk-based Burnt Mill, tells me. “It’s pretty strange that a beer can taste how you’d expect when taking a sample straight from the [tank] but opening up a can straight off the line it feels like something is a bit off.”

Zoe agrees with my assessment that freshly packaged beer tastes “unbalanced, like all those lovely hop aromas and yeast esters are disjointed from the malty background.” It’s interesting to hear that tank samples taken before packaging don’t taste this way, reinforcing my theory that the very act of packing and immediately shipping beer is having a short-term negative effect on its flavour. 

Bottle shock isn’t solely the premise of beer either. In fact the term comes from the wine trade and is also sometimes referred to as “bottle sickness.” In an article for Wine Enthusiast from June 2020 by Paul Gregutt, he describes wines that have recently been packaged or shipped as having “aromas and flavours that have seemingly shut down.” It’s not uncommon when opening a bottle of wine to let it rest or air in order for its flavours to open up. But with beer (especially with it being carbonated and served cold) this isn’t generally an option. No one wants a warm, flat beer. 

What’s interesting is that it could be carbon dioxide itself that causes the flavours in beer to temporarily go into shock. The gas is not only used to push beer out of its conditioning tank and into a canning or bottling line, but the vessel it’s packed into will also have been flushed with carbon dioxide prior to being filled, in order to prevent any oxygen ingress. There is no scientific data that backs this up, but several brewers agreed with me that their beer always seems to taste better a few days after settling. 

“I always find it’s like trying to taste into the future,” London-based Wild Card Brewery’s head brewer Jaega Wise tells me. “I’ve not heard the phrase ‘can shock’ before. But it’s really normal, especially with super hoppy beers. It just needs time to calm down, a bit like a curry you eat a few days later…”

While my technical research was largely inconclusive, the anecdotal evidence seems undeniable. It makes sense if you think about it. Unpasteurized beer is a living product, and a delicate one at that. If you’re going to force it through a hosepipe into a tiny aluminium container and then ship it across the country in the back of a van, then it’s going to affect how that beer tastes. Perhaps the prevalence of more intensely flavoured beers combined with the availability of freshly-canned beer from breweries is making it a little more obvious than it used to be. At least, thankfully, it seems to be just a temporary issue.

While I don’t want to stop you from tearing into your latest haul with abandon, it might pay dividends to let it settle in order to get the best out of your beer. Can or bottle shock, it seems, is definitely a thing. And the only real way to solve it is with a fridge, and a little bit of patience.

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