Wednesday, 15 April 2009

Now I know what skunked is

The other week, while meeting with Joe for a beer in Brussels, the topic of skunking was mentioned. Although I understand the chemistry of it, and why brown glass is preferable to green or clear glass, I had to admit that I wasn't sure exactly what that flavour was, and that from reading I imagined it to be something powerfully awful. Joe asked had I ever tasted Heineken. Well, yes, of course. But if it is all skunked, how would I know what to compare it to?

As fate would have it, two days later my neighbour left two bottles of Heineken outside my door. In the past the offerings have been more exciting, but actually, this was perfect timing. The sun was blazing over the long weekend, so I left one bottle out on the balcony for three days, and the other safely secured in the fridge. Last night, I opened them. Here's what happened:

Heineken isn't my favourite beer in the world, not by far, but if there's sod all choice, I'll take it. I've never thought about it much, but I suppose there's a perfumy hop thing going on, and a thin, sweeting malt base. It's probably not the worst beer in the world.

Sniffing the one that was in the sun for three days gave me a rather strong plastic aroma, with a touch of sulpher and perhaps a touch of stale urine. But in the mouth? I thought I was going to gag for a moment. Absolutely awful! If this is skunking, then I have never tasted it before. There has been alot of debate amongst ICB members about beers from Shepard Neame that come in clear bottles, and some people were quite sensitive to the beer being light struck. I have to admit I only occasionally got a sense of staleness, but nothing like this awful burnt plastic and piss flavour. I had to gargle with the unskunked Heineken to try to get the taste out of my gob. That didn't work. Neither did chocolate. Tortilla chips helped.

I was tempted to run this test again with some Jever, as it's definitely more hoppy than Heineken and should interact with the light more strongly. If that will only intensify the awful taste, I'm not sure I'm up to it!

My wife didn't believe me, so actually, I will do the Jever test!


Lars Marius Garshol said...

I seem to recall that only beers made with real hops, as opposed to hop extract, are susceptible to skunking. I'd have thought that Heineken would be made with hop extract, but clearly one of those two assumptions is wrong.

Anyway, I've never tasted skunked beer, either, so I assume it's actually quite rare. Seems to be mostly a US problem, as far as I can tell.

Oblivious said...

Hop extract is generally are isomerized to create the bitterness as per hop in the boil. An it's the UV wavelengths that attack the double bonds.

But the is supposed to extract available now that is supposed to more resistant to light striking

E.S. Delia said...

Pilsner Urquell is one that I find myself buying for parties or just to have a few around the house to enjoy when I'm not nerding out on beer. I still think it's good stuff.

Point being, since it also comes in the green glass bottles, that makes it more vulnerable to skunking. By opting for the covered 12-packs as opposed to the open 6-packs, I avoid the skunkiness since light has a tough time getting through all that packaging.

Pivní Filosof said...

Several years ago I taught the Plant Manager of the company that makes the bottles for Pilsner Urquell and pretty much all the other Czech breweries.
I don't remember the details anymore, but he mentioned once that they had developed a new formula for green glass that protects the beer for considerably longer, not as much as brown glass, but not much less either (if I remember right).
Now, I wonder what would happen if you did the same experiment with a brown bottle. 3 days in warm sun is quite extreme and I think it will seriously affect any sort of beer in a glass bottle of any colour.

Barry M said...

Lars, my understanding was as Oblivious pointed out, that extract is simply ready isomerized hop juice, but have also heard about treated extract that is resistant to skunking.

Eric, I believe my neighbour also had a cardboard-wrapped pack, so the unexposed one was a reasonable comparison. He seemed quite pleased to have them, but I suspect he picked them up across the border. Now that I think of it, I'm not sure you see a lot of Heineken around these parts. I must keep an eye out. It'd be amazing if it wasn't popular (maybe).

Mr. Filosov, I was considering an experiment with brown bottles, just as a comparison. You're right though, three days is extreme :D As I understand it you only need a short time of exposure, but I don't know how long is needed to get a real skunk effect. Does anyone know? Three days definitely did it! I could leave a batch out, each left for different periods just to see what happens. There's a 6-pack of Beck inthe office that might make a good candidate for that (green glass of course). I'd probably use some of my own homebrews for the brown bottle test.

Salacious said...

heat/temperature changes on tJames Spencer from Basic Brewing Radio performed a similar exercise a few years back, but included a control.

He left Sierra Nevada Pale Ale (considerably more hoppy than Heineken) out in the Arkansas sunlight for 30 minutes and it was sufficient for a pronounced skunkiness in the beer.

Barry M said...

Hi, what was the control in James's case? My control was a bottle left in the dark fridge for comparison.

3 days in the German sun was extreme. I know I could try it after an hour or so, but I still haven't the heart to do this again, even with beers I don't like. :D

Salacious said...

If memory serves me correct, I believe that he tried:

(1) glass poured, but covered by upside-brown paper bag [control]

(2) glass poured and left in sunlight

After leaving both (bag/glass) exposed to the sun for 30 minutes, he sniffed and drank of each.

I'm tempted to perform the same experiment myself, except that it is so difficult to get anything with hops here (Berlin)!

Barry M said...

If the bag worked, it could be an essential piece of summer beer drinking equipment :D