"This beer's been skunked!" Most of us have heard this, or even exclaimed it ourselves. There is an easy litmus test for determining whether a beer has been skunked. Smell it, and if smells of skunk, it's been skunked. But what causes it? It is intentional? How can I avoid it?
Beers can become skunked, or light-struck, when isomerized alpha-acids (which derive from hops) are exposed to visible or ultraviolet light. There is no other way for a beer to get skunked. Fluctuating temperatures cannot do it, and while some brewers try to produce this skunk aroma and flavor, they don't get there by skunking their beers.
Skunking happens when these acids react with light and sulfur-containing proteins in the beer that creates 3-methyl-2-butene-1-thiol, a stinky sulfur chemical that is exactly the same chemical a skunk produces to make it's awful olfactory defense. So to keep your beer from getting skunked, simply ensure that it doesn't get exposed to light. It sounds simple enough. Kegs and cans, being impenetrable to light, offer the only real protection. Brown glass bottles absorb most of this deleterious light, protecting the beer inside adequately well. Green bottles only absorb green light, leaving the rest of the spectrum to penetrate and skunk the beer. White bottles offer virtually no protection, and are by far the worst option for beer.
So why don't brewers eliminate green and clear bottles? Because their customers are accustomed to the existing colors. And who would trust a Heineken in a brown bottle? (See below)
So brewers come up with other methods to hide their skunky beers. Some try to hide the skunkiness, while others alter the chemistry of the beer itself. Just think about all the beers you know that are served in clear bottles. Take Corona, which is typically served ice cold in a clear glass bottle with a lime jammed into the top. The ice cold temperature hides the taste of the beer, and the lime jammed in the bottle prevents the smell from escaping and masks the taste. It's almost as if they don't want you to smell or taste their beer. But, honestly, I've never had a Corona, so you can all be your own judge on that. Another method to avoid skunking is practiced by the Miller Brewing Company. They have replaced hops with tetra-hops, which are chemically different from normal hops and cannot be light-struck.
If you really want to experience the full range of skunkiness, you can try what I did. I purchased a six-pack of Heineken in the trademark green bottles, a six-pack of Heineken in the funky shaped cans, and a six-pack of the Heineken Dark Lager (in those sketchy-looking brown bottles) for good luck. The Heineken bottles were stored at the store in a well-lit case, which almost certainly already initiated the skunking process. I took them home, put five of them in our dark mini-fridge, and one on our window sill to get truly skunked.
Come Friday night, myself and three others are prepared to explore the skunky world of Heineken. We started with the green bottled variety, poured into pilsner glasses to showcase the color. Before sipping, we passed the brews around for each other to smell. When you drink Beer with Ben, that's the type of experience you'll get. Of the four, only one did not have any appreciable amount of skunky aroma. My beer was a typical, slightly skunked, yet still drinkable Heineken. It had both a nice hoppiness and bitterness, but the skunk flavor overwhelmed the other flavors.
We moved on to the canned variety, and one of us commented in surprise, "It's a different drink entirely!" The difference was obvious; the skunk smell and flavor were completely gone. The hops and slight bitterness were now the primary flavors, and while it still is a somewhat restrained pale lager, it was absolutely a step up from the bottled variety.
Before we dared open the window-sill bottle, we tried some of the Heineken Dark Lager. It poured surprisingly dark, and smelled of roasted malts and hops. Most of us in attendance were stout fans, so we all liked this Dark Lager over the previous Heinekens. But if we were faced with almost any other stout or stout-like brew, we would surely choose that over the Heineken Dark Lager.
Finally, we were prepared for the window-sill bottle. I poured it into a pint glass and it looked the same as the other bottled Heinekens, but the skunk smell was immediately apparent. We passed the glass around, hesitantly sniffing with pained looks on our faces. Even the non-beer-drinkers in attendance took a whiff, and were repulsed. Those daring enough to sip it were glad their previous beers weren't stored on our window sill, as the skunk taste really overwhelmed and ruined the beer.
So don't let people tell you that beers are supposed to be skunked. It might be expected in some instances, but people are not naturally attracted to this flavor. If you've developed a taste for skunked beers, then by all means continue drinking them. Just not within smelling range of me and my beers.
