Its time now to reveal that why CORONA is served with the lemon slice
Skunky beer is a well-known flavor defect, and everyone seems to have a theory as to what causes the beer to go funky. But its alternate name, “light-struck” beer, hints at the true cause. As the name suggests, the phenomenon occurs when light-sensitive hops — a major beer ingredient that acts as a preservative and adds flavor is exposed to too much light. Brewers have documented the problem since at least 1875. To combat it, beer is often stored in brown or green glass bottles to help filter out the light (aluminum cans and kegs block out light completely).
In 2001, chemists from the University of North Carolina at Chapel Hill figured out the details of the skunked beer. The scientists shot lasers at three isohumulones — the compounds responsible for hops’ light sensitivity — and used a device called a time-resolved electron paramagnetic spectroscope to measure the compounds that were created in the process. The focused laser light broke down the isohumulones, producing 3-methylbut-2-ene-1-thiol(3-MBT), or “skunky thiol,” which is chemically similar to the compound in a skunk’s glad that gives their spray such an intense smell.
In the real world, where beers aren’t bombarded by lasers, light-struck beer is due to visible light between 400-500 nanometres in wavelength (the blue end of the spectrum) and ultraviolet light, which has a wavelength of less than 400 nm. Brown bottles block out light under 500nm, and green bottles block light below 400nm, which is why the occasional Carlsberg, Heineken will taste off.
Brown glass provides 98%, green provides 20% and white glass zero protection against light, and Humans are remarkably good at detecting 3-MBT just four parts-per-trillion of the compound can be noticeable, making it one of the most powerful flavours in beer which is why Corona advertisers cleverly suggest you drink their brew with a slice of lime because this off- flavour can be masked with lime.
Humans are remarkably good at detecting 3-MBT -just four parts-per-trillion of the compound can be noticeable, making it one of the most powerful flavors in the beer.
You can now find cans of some of the most commonly affected beers like Heineken and Corona (or Corona Familiar, which is the same beer as Corona Extra but packed in large, brown bottles), and these packages are a better representation of how the beer should taste. Miller Brewing still uses clear bottles for some of their brands (High Life), and they skirt the lightstruck issue by using specially formulated hop extracts that do not react with UV light to create 3-MBT.
If you’re drinking a beer where the predominant flavor is that of a skunk’s musky juices, perhaps it’s time to look to some different brews.