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  • Beer bottles are typically just three colors.

  • But does the color matter?

  • A bottle's color determines just how much light gets through to the beer inside.

  • Light may not seem like a big deal, but it can cause chemical reactions in beer that

  • affect the taste.

  • Brewers call these beerslightstruck.”

  • Molecules from hops known as iso-alpha-acids are what make beer bitter, but they also make

  • beer vulnerable to light.

  • Visible light breaks apart these iso-alpha-acids with the help of riboflavin, also known as

  • vitamin B2, from barley malt.

  • One of the resulting molecules, known as an oxyl radical, loses oxygen and carbon atoms

  • and becomes a carbonyl radical.

  • That molecule is eager for a new partner to bond with, and it finds one in sulfhydryl

  • molecules that form when visible light breaks apart amino acids found in barley malt.

  • When they pair up, they form a new compound called 3-methyl-but-2-ene-1-thiol, which is

  • a bit of a mouthful, so it's often referred to as 3MBT.

  • 3MBT happens to be very similar in structure and chemical makeup to the compounds responsible

  • for a skunk's distinctive odor, and we can taste it at just a few parts per billion.

  • Some brewers use specially treated hop extracts so iso-alpha-acids won't break apart and

  • form 3MBT.

  • But even these beers may not be safe from funky flavors.

  • Light can still cause a reaction that forms a molecule called 2-sulphanyl-3-methylbutanol,

  • which tastes like onion.

  • Different bottle colors block different amounts of light.

  • Unsurprisingly, clear bottles offer no protection from light, and green bottles aren't much

  • better.

  • But some brewers still use them and customers have come to expect skunky beer that might

  • require a slice of citrus.

  • Amber bottles are most common for a reason.

  • They block the most light, almost completely stopping skunking.

  • But if you want to avoid these pungent molecules, your best bet is to stick to sipping beer

  • from cans.

  • For Scientific American, I'm Kelsey Kennedy

Beer bottles are typically just three colors.

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玻璃瓶的颜色如何影响里面的啤酒(How Does the Color of a Glass Bottle Affect the Beer Inside?)

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    joey joey 發佈於 2021 年 05 月 15 日
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