Speaking of brewing outside...

[cweston]

True or false: sunlight exposure of hops leads to "skunked" flavor, even during the boiling of the wort.

I always thought this was true (and therefore that brewing, or boiling the wort anyway, should always be done in the shade.)

 

[Chairman Cheyco]

Some good info in this thread:
https://www.homebrewtalk.com/showthread.php?t=6486

Your point about the shade makes sense to me.

 

[parasonic]

I doubt that sunlight exposure to hops ever hurts them...after all, they DO grow in the sun.

As for during the wort boil, the results are probably negligible, but I would definitely play it safely and do the boil with a lid on and/or in the shade. "It's better to be safe than sorry," and if you do get skunkage, you have thereby eliminated a variable!

 

[Ivan Lendl]

i had a question about this a while ago...i think the hops have to be isomerized,(chemically altered through boiling) or something before they are subsecptable to light skunking. As long as your not brewing on the beach using a glass kettle, you should be fine.

 

[Kaiser]

but I would definitely play it safely and do the boil with a lid on and/or in the shade. "It's better to be safe than sorry," and if you do get skunkage, you have thereby eliminated a variable!

If you boil with the lid on, you may get other skunkage (i.e. DMS)

Kai

 

[RichBrewer]

I brew outside and I take care when I'm transferring from the kettle to the carboy. I cover the carboy with a black t-shirt and keep the transfer line out of direct sun light.

 

[DrewsBrews]

I thought it was the yeasties that had the vampire complex. I've brewed out in the sun (what sun we get in western Washington) with the lid off and haven't noticed any problems with skunky odor in the finished beer.

Once I dump the yeast in the primary, I cover that sucker up with a dark towel and it doesn't come off until I rack.

Am I totally wrong on this and just lucky?

 

[Baron von BeeGee]

This topic captured my imagination (and I'm tired of working on a presentation at work), so I did a bit of research and found this:

http://www.sciencenews.org/articles/20051203/bob8.asp

Brewing chemists attribute skunky flavor to 3-methylbut-2-ene-1-thiol, a constituent of skunk spray. This compound arises from a reaction that light triggers within the beer, and the resulting taste can overwhelm other flavors.

"Humans are very sensitive to this compound," says Denis De Keukeleire of Ghent University in Belgium. 3-methylbut-2-ene-1-thiol is detectable in quantities as small as 0.004 microgram (µg) per liter. This amount can form in minutes when beer is exposed to bright sunlight, he says.

Riboflavin, a compound produced by yeast during fermentation, absorbs energy from light at wavelengths of 350 to 500 nanometers (nm). It transfers the energy to iso-alpha acids, the compounds that give beer bitterness. They then release free radicals—small, unstable chemical fragments—that react with sulfur compounds produced by the yeast. The result is the offending thiol.

So if I read this correctly, hops being skunked is a post-fermentation phenomenon due to the presence of riboflavin being required to release free radicals from the alpha acids.

Another interesting link which corraborates the above articles information regarding 'modified' hops that won't skunk (and hence Newcastle and Miller are able to package in clear bottles):
http://research.unc.edu/endeavors/win2002/beer.htm
Also mentions that Corona is packaged in boxes to prevent skunking which pretty much throws out the assertion that Corona intentionally skunks their beer before packaging (which I never found very credible, anyways)...and that link comes from UNC-Crapple Hole where they consider Corona excellent beer.

 

[Kaiser]

http://research.unc.edu/endeavors/win2002/beer.htm
But according to beer purists—such as a particular group of Germans—that product is no longer considered beer

yep, that's what I thought to when I read of modified hops. But in Germany all beer seems to be bottled in brown bottles (with the exception of Becks and some others I believe) and there is a deposit on the bottles, which makes recycling easier

Luckily we home brewers don't have to worry about uncertain transport and/or storage scenarios

Kai

 

[DrewsBrews]

So if I read this correctly, hops being skunked is a post-fermentation phenomenon due to the presence of riboflavin produced by yeast during fermentation being required to release free radicals from the alpha acids.

Ahh... so I was half-correct (same as being half-a$$ed). At least we now know that brewing in direct sunlight is okey-dokey. I edited in the bold text, BTW.

Thanks for the research Baron. Speaking of sunlight, the sun is making a rare early-spring appearance here and nobody but me is in the office (funny how everyone else in my office group finds reason to be outdoors when the sun pops out). Guess no one will notice I'm online, then.

 

[MrSaLTy]

One interesting thing I learned from the brewing network shows was that the reaction that causes skunkiness can and will continue even after its removed from the sunlight. Once it starts your hosed so drink up fast.

 

[DrewsBrews]

One interesting thing I learned from the brewing network shows was that the reaction that causes skunkiness can and will continue even after its removed from the sunlight. Once it starts your hosed so drink up fast.

Brewing network shows?! On what channel did you see these, man?

 

[brewhead]

http://www.thebrewingnetwork.com/

other good resources are:

http://www.basicbrewing.com/

http://www.craftbeerradio.com/

all these can be subscribed to via podcast

 

[cweston]

Speaking of sunlight, the sun is making a rare early-spring appearance here and nobody but me is in the office (funny how everyone else in my office group finds reason to be outdoors when the sun pops out). Guess no one will notice I'm online, then.

Ah--I remember this phenomenon well from my Seattle days. Any warm, sunny afternoon during the rainy season, everyone seems to find a way to not be at work, school, wherever. I can remember hitting Greenlake on a few such weekday afternoons and it seemed like the whole city was there.

Through a long and winding route, we now find ourselves living in Kansas, where the locals start slitting their wrists after 3 straight days of overcast weather. We often wonder if we'd ever be able to survive a PNW winter now.

 

[El Pistolero]

Kansas, where the locals start slitting their wrists after 3 straight days of overcast weather.

The locals...all ten of them?

 

[cweston]

The locals...all ten of them?

Just the opposite, actually: in the northwest, practically everyone is from somewhere else. A pretty high percentage of Kansans are homegrown, though.

 

[MrSaLTy]

Brewing network shows?! On what channel did you see these, man?

What brewhead said. IF you go the the site http://www.thebrewingnetwork.com/

you can go to the archives and download almost any show they have had. There is some fluff on the sunday shows but they do some really great interviews and I have learned a lot from them.

 

[El Pistolero]

Just the opposite, actually: in the northwest, practically everyone is from somewhere else. A pretty high percentage of Kansans are homegrown, though.

Yeah, but isn't Manhattan mostly college students and KSU employees?

 

[cweston]

Yeah, but isn't Manhattan mostly college students and KSU employees?

Oh, yeah (duh--now I get what you mean). By college town standards, though, not so much. (A pretty large percentage of our students are from Kansas.)

 

[bikebryan]

Oh, yeah (duh--now I get what you mean). By college town standards, though, not so much. (A pretty large percentage of our students are from Kansas.)

Not to mention that most of the students are there for most of the year.....

Oh yea, and Kansas is completely flat. If you believe that, I'd love to sit you on a bicycle and send you on US18 Between Junction City and Manhattan. Oh, and ride around Topeka. Parts of Kansas are pretty hilly....just like parts of Kansas do have a decent amount of peopple, and pretty much most of them are home-grown.

 

[cweston]

Oh yea, and Kansas is completely flat. If you believe that, I'd love to sit you on a bicycle and send you on US18 Between Junction City and Manhattan. Oh, and ride around Topeka. Parts of Kansas are pretty hilly....just like parts of Kansas do have a decent amount of peopple, and pretty much most of them are home-grown.

Heh: I see you're familiar with my part of Kansas. I had managed to live almost 40 years without really ever thinking about Kansas before I took a job here. I was literally shocked at what the landscape of the Flint Hills (the part of Kansas where I live) looked like. The lack of trees on the prairie is a little shocking at first, but it is quite hilly and really is quite beautiful in its own unique way. Like most people, I had no idea that there was any part of Kansas that looked like that.

EDIT: here's a pic from a few miles from my house, looking into the Kansas River valley. Looks like you can see a tiny bit of the river in this pic.

 

[DrewsBrews]

Just went to the Brewing Network site for a couple of minutes. So now I can make beer... read about people making beer... and even listen to people talk about making beer.

There just isn't enough time in the day, folks...

 

[bikebryan]

Heh: I see you're familiar with my part of Kansas. I had managed to live almost 40 years without really ever thinking about Kansas before I took a job here. I was literally shocked at what the landscape of the Flint Hills (the part of Kansas where I live) looked like. The lack of trees on the prairie is a little shocking at first, but it is quite hilly and really is quite beautiful in its own unique way. Like most people, I had no idea that there was any part of Kansas that looked like that.

EDIT: here's a pic from a few miles from my house, looking into the Kansas River valley. Looks like you can see a tiny bit of the river in this pic.

That's the view I grew up with. I was born/raised in Junction City. I attended KSU for two years before my study of Hops & Malted Barley (ie, drinking too much) forced me out of school and I joined the AF and settled my life down.

My folks still live in Junction City. I visit when I have the chance, but haven't been able to for the last couple of years. I may have spent most of my adult life in Texas, and now live in Alexandria, VA, but my heart still beats true-blood Kansan.