Dubai, United Arab Emirates (CNN) – Have you ever opened a bottle of beer, poured it into a clear glass, left it in the sun and sipped it again after a while … have you ever tasted it? Taste? What happened?

If you have experienced this funky bait, it is due to the chemical composition that smells like unpleasant skunk. That is why the breweries call this process “skunk”.

Chuck Skibek, technical director of Browning Enterprises at The Brewers Association, owns Kraft Breweries and has been in the business for 21 years. He said the reason for the smell of skunk was not really understood until the 1960s.

When barley in beer is exposed to strong light, it undergoes a photo-antioxidant reaction, forming 3-methyl-2-butane-1-thiol. To prevent this skunk process from happening, the brewers opted for dark colored glass. That’s why you see a lot of beers being used in brown glass bottles today.

“It’s a simple reaction, which most people describe as an unpleasant taste,” Skibeck explained, adding that “anything that protects the beer from the photooxidation process will preserve its flavor, so it is served as desired by the brewer.”

So Brown was the choice of a typical brewer, but this is not the only thing we see in beer bottles, some people even use green glasses. Why? According to Skype, green does not protect from light like brown, but its use is primarily marketing.

“Most brands written in green glass are very old and outdated in the market,” he said. He added, “A good number of European breweries use sunglasses. Green bottles reflect their marketing image. Again, for decades, quality and exclusivity have been associated with sunglasses.”

And the green glass should be dark enough to prevent the chemical skunk process.

Skype said it was more desirable to choose glass as a packaging material than plastic because consumers see glass as more environmentally friendly, of higher quality, and prevent beer spoilage.

Metal cans are a popular packaging option and do not allow light, but photo-oxidation is possible due to the hot aging process. Skype says further research is needed in this area to determine the best package to reduce this.

For any other beer storage guidelines to prevent oxidation, spoilage or taste changes, Skype has a simple rule: cold and dark.

“Beer consists mainly of water and barley. It is a food that, like other foods, loses its freshness,” he said. The light is the chemical reaction we are talking about, which is the exposure to oxygen and high temperatures.