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Old 01-06-2012, 01:27 AM   #11
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Originally Posted by eastoak View Post
big breweries use hop stabilizers or something like that.
Miller uses hop stabilizers. Other breweries just have marketing departments that like the green or clear bottles, and those beers WILL skunk in minutes if you stick them outside on a clear summer day. Everyone thinks of Heineken, Corona, etc. but Pilsner Urquell is just as much to blame.
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Old 01-06-2012, 01:27 AM   #12
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the reason breweries use colored bottles is for the light exposure in the months they might spend on the shelves, not the minutes spent bottling. almost all of us brew during the day. i have for years, and no skunkiness yet...

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Old 01-06-2012, 01:58 AM   #13
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Other breweries just have marketing departments that like the green or clear bottles, and those beers WILL skunk in minutes if you stick them outside on a clear summer day.
Do you have irrefutable data and or links to back up this claim that hop skunking will happen in "minutes" in daylight? If so please do share. It's quite amusing being hops themselves grow in sunlight and are harvested in daylight, and yeah I know they haven't been isomerized yet. Not saying skunking is a myth, not at all, but come on... minutes???


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Old 01-06-2012, 02:08 AM   #14
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Guys. hops skunking has to do with the interraction of isomerized alpha acids,and sunlight in fermented beer. Not unfermented wort.

That's why we have no problems with brewing outside in broad daylight.

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Old 01-06-2012, 02:09 AM   #15
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Do you have irrefutable data and or links to back up this claim that hop skunking will happen in "minutes" in daylight? If so please do share. It's quite amusing being hops themselves grow in sunlight and are harvested in daylight. Not saying skunking is a myth, not at all, but come on... minutes???


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Well the reaction occurs with iso-alpha acids, which you don't get until you boil the hops or perform some other process to isomerize the alpha acids.

I have seen several experiments in the past, and seem to recall a noted brewer (maybe Matt Brynildson?) relating notable skunking in his beer as the pint made its way to his table across a long sunny patio area over the course of 5-10 minutes.

And Basic Brewing did an episode about this a while back, as well. They get pretty notable skunking after letting the beers sit out in the sun for about 45 minutes in this video:

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Old 01-06-2012, 02:09 AM   #16
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Do you have irrefutable data and or links to back up this claim that hop skunking will happen in "minutes" in daylight? If so please do share. It's quite amusing being hops themselves grow in sunlight and are harvested in daylight, and yeah I know they haven't been isomerized yet. Not saying skunking is a myth, not at all, but come on... minutes???


Rev.
Hop skunking, in beer, WILL happen in minutes in sunlight.

The basic brewing guys proved it here....

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Old 01-06-2012, 02:10 AM   #17
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Well the reaction occurs with iso-alpha acids, which you don't get until you boil the hops or perform some other process to isomerize the alpha acids.

I have seen several experiments in the past, and seem to recall a noted brewer (maybe Matt Brynildson?) relating notable skunking in his beer as the pint made its way to his table across a long sunny patio area over the course of 5-10 minutes.
LOL. great minds think alike.
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Old 01-06-2012, 02:10 AM   #18
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I use clear and green bottles, but all of my bottles are boxed up until ready to drink. Never had a skunker!

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Old 01-06-2012, 02:17 AM   #19
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An in depth explanation of how skunking occurs, and why some beers in clear bottles DON'T skunk.

From the Washington Post.

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Only recently (in 2001) did we figure out how light causes skunkiness. Chemists at the University of North Carolina and Ghent University in Belgium found that when exposed to light, the alpha acids in hops break down into free radicals that then react with sulfur-containing proteins to make a chemical called 3-methyl-2-butene-1-thiol, which is virtually identical to the principal constituent of skunk juice. Any time you see "thiol" in the name of a chemical, you can bet it's going to stink. Humans can detect this particular thiol at concentrations as low as one-billionth of a gram per 12-ounce bottle of beer. Apparently, skunks really know their chemistry.

So if skunkiness is caused by light acting on chemicals in hops, and if virtually all beers contain hops, how does Miller get away with using colorless bottles for its Genuine Draft, which has replaced its High Life? (It's the same recipe, but Genuine Draft is cold filtered instead of being pasteurized, as High Life was.)

Chemical trickery, that's how. Instead of using actual hops for bittering the beer, Miller uses a chemically modified form of hops' alpha acids known by several brand names, among them Tetrahop Gold. It does not produce 3-methyl-2-butene-1-thiol when struck by light, but according to the Ghent chemists, it can still produce rotten-egg odors. Uncolored bottles are cheaper than colored ones, however, so Miller's fiscal folks apparently prevailed over their flavor mavens.
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Old 01-06-2012, 02:18 AM   #20
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And here's a timed experiment of skunking of various beers.

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Skunking Beer Experiment - Results

Curious just how quickly sunlight can destroy a beer? Here are the results from our beer skunking experiment. You can try this very experiment in your own home! Note that we did these tastings blind, but I list the results in order so you can read through without confusion.

Corona Light - clear bottle
The bottle not exposed to sunlight was perfectly clean smelling and had a fresh flavor. This was the control bottle and it tasted quite fine. The bottle exposed to sunlight for 1/2 hour was clearly toast. It had a bad smell right from the bottle, and a bad, off flavor when drunk from a glass. It got worse. When we had the bottle exposed to sunlight for 3 hours, it was awful. The skunky smell was very obvious from the bottle and the flavor was clearly wrong.

Heineken Light - green bottle
A green bottle does NOTHING at all to prevent skunking. The wavelengths that cause skunking in beer go right through green glass. The control bottle of Heineken had a very light flavor and aroma. It hadn't been harmed at all. The 1/2 hour exposed to sunlight bottle was clearly skunked. You could smell it from the bottle and taste the bad flavor in the glass. What was impressive was how awful the 3 hour sunlight bottle. This was even worse than the Corona Light - a very strong skunky aroma, a very sharp flavor.

Miller Lite - clear bottle
The first, no-sunlight bottle had a fresh flavor and light flavor. Impressively, while the 1/2 hour and 3 hour versions did have a noticeable off aroma and flavor to them, both were *far* less than the Corona or Heineken. We're heard rumors that Miller has a special technique in how they brew to keep their hops from being able to get skunked. Maybe it's true!

Michelob Ultra Amber - brown bottle
Brown bottles don't totally prevent skunking, but they do slow it down quite a bit. We were impressed with how it helped. The non-sunlight bottle had lovely, gentle flavors. In fact our beer maker commented that he was quite impressed that this was a low carb beer. The 1/2 hour sunlit bottle seemed to be about the same, with maybe a tiny hint of change. Even the 3 hour in sunlight bottle, while it seemed a little "off", didn't seem to smell or taste skunky. We could tell that it was a bit different, but it didn't seem "bad".

Smithwick's - brown bottle
This was our control bottle, it is not low carb. This is an Irish beer. The one not exposed to sunlight was fresh and lovely tasting. The one left out for 1/2 hour was a tiny bit different, but just about the same. The one out for 3 hours did have an off aroma, but it was mild.

Results
We proved quite thoroughly that beer can be skunked in only 1/2 hour of exposure to sunlight, and that both Corona and Heineken are extremely sensitive to light. We were very impressed with how brown bottles helped to protect beer against this harm - although it should be noted that if you pour your brown bottle beer into a clear glass, it is now exposed to sunlight We were also very curious to learn what Miller Lite does to its beer to help keep it safe! I'll let you know when I hear back from them.

Feel free to ask me questions about this experiment, or to try it out for yourself!

NOTE: I wrote Miller to ask them how they achieved these great results. Here is their response:

We currently only use hops grown in the United States. The major growing areas are in Oregon, Washington, and Idaho. Some of the types of hops we use include: Cascade, Cluster, Fuggles, Galena and Mt.Hood. Unfortunately, because it is proprietary information, we cannot disclose which hops are used in which brands.

In addition bottled beer exposed to sun or other light sources can undergo a slight photochemical change that sometimes can give the beer a skunky aroma, however, the beer would not get skunky. It would take approximately one minute for this change to take place. Cans provide the most protection from light, and generally product in amber bottles is LESS likely to suffer the effects of light than beer packaged in clear or green bottles. The exceptions are all Miller products that are sold in clear bottles. Miller's understanding and use of special hops enables us to produce a beer that is much more light stable. However, other subtle flavor changes can occur with exposure to too much light. So, keeping any bottled beer (clear or amber) out of direct sunlight helps preserve that just brewed flavor of our products.

Beer is most susceptible to light exposure in the 290 - 425 nanometer range. Amber glass does an excellent job of preventing light from reacting with product in this range.

From a visitor: "It's not about their secret All-American special hops, they use Tetrahop Gold(TM), which is a chemically modified hop extract. The WaPo did a story that explains it."
Is any of this data irrefutable enough????
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