Light Striking

[reVoxAHB]

Hi Gang,

I'm interested in learning more about light striking of beer, as preventative measure. From what I've grabbed in my books and via google:

General Definition of Light Strike:
When a beer comes in contact with light and becomes 'skunky' it is said to have suffered light strike. This condition can occur quite quickly, after as little as 30 minutes in bright sunlight. Beer has traditionally been put in brown bottles to reduce exposure to light.

Technical:
Skunking occurs when rays of ultraviolet light strike hop-derived molecules called isohumulones, which give beer its distinctive bitter taste. By breaking a bond that bridges two parts of the isohumulone molecule, light creates two new compounds. The smaller one binds to sulfur atoms from nearby proteins to create what Zare calls "essence of skunk" -- not exactly the same foul-smelling chemical that gives skunks their swagger, but close. The compound is so potent that even amounts in the parts-per-trillion range can ruin a beer. source: Stanford Report, November 2, 2001
"Chemistry professor explains the 'fizzics' of beer" http://news-service.stanford.edu/news/2001...7/beer-117.html

I know it's pretty simple: keep your conditioning bottles out of direct light, preferably in a dark cellar or cupboard, etc.

But what about indirect sunlight? Like natural light bouncing around a liquor store/bottle shop/my kitchen?

What about both direct and indirect light coming off of a light globe (artificial source)?

I've recently installed a light globe to my fermentation fridge, with some great suggestions from other AHB members with how to "cover/blacken" the globe.

Was considering inserting the globe to a terracotta pot. Wondering if the little bit of indirect artificial light coming off a 40 or 60W clear globe, bouncing around the inside of the fridge, would have the strength to strike beer fermenting in a GLASS clear carboy?

Cheers,
reVox

 

[warrenlw63]

reVox

Light strike threads always wind up very long and drawn out like batch vs. fly sparge or Immersion vs. CFWC vs. No Chill. You'll probably get differing opinions however I've fermented in glass carboys for years with an uncovered light-bulb in winter.

Never noticed a problem with light strike whatsoever. So I'd say you'd be fine. OTOH if you're worried an infra-red reptile bulb (which I use now) or some foil or terra cotta pot (as you stated) on the bulb will be fine.

Warren -

 

[DarkFaerytale]

my 2C - wrap the carboy in a towel, it's what i do

-Phill

 

[jayse]

As far as using a light bulb in a fermentation box goes>
The intensity of the wavelenghts that produce the skunking of beer is very very low in a incandescent bulb.
They really only produce the much higher reds and yellows 700nm-550nm down around the 450-400nm the intensity of whats produced would be so low it wouldn't matter to much I wouldn't think and I doubt anything lower than 400nm would be produced much at all.

Quick edit> A flouresent tube is a big no no because the wavelengths produced are down around the lower end and is why they should not be used directly near beer bottles in pub/club bottlo fridges. The same would go for fermentation areas etc. I don't think the intensity is that great from a reasonble distance though so if you had bottles stored in a shed which had a couple tubes in the ceiling it wouldn't affect it a great deal I'am guessing.

 

[delboy]

light strike

only occures because of ultra violate ,
and an incandecent globe is fine .unless it is one of thoughs phillips blue natural incandesants(white light from a bulb)
its the blue level of radiation that dose the damage uvb/uva.
as for 30 mins in the sun .myth
as for 30 min in a pub fridge or desplay fridge myth.

now brown bottels (amber) filtres blue light down ,clear bottels not so good
they are usually skunct in around 48 - 72 hours continious light.
but then how many scunkt beers have you had out of clear bottels ?
i have ever only had several myself
hahn light , was next to an incorect fluro fitted buy publican in bar disply fridge. should have been a (warmwhite )as recommended

a Carona that was in a fridge at BwS was also stacked next to a fluro of the wrong wave length .


now saying all that it dose happen over time YES. in 30 mins NO (direct sunlight or fluro)

hope this answers your question.

Delboy
PS for the knockers of my comments (I used to supply and fit pubs and clubs with the corrected wave length fluros for there display fridges)

yellow furos are ok as well (green get away with) blue well thats the wave length your trying to cut out.
and no yellow celaphane over a normal fluro dont work.UV DESTOYS CELEPHANE.

 

[Little_Squares]

I say keep it all dark to avoid the possibility of creating lightstruck beer - there's enough else to go wrong without this most foul defect.

A small domestic fridge light isn't going to do any harm unless it's always on......

 

[Ross]

as for 30 mins in the sun .myth
as for 30 min in a pub fridge or desplay fridge myth.


they are usually skunct in around 48 - 72 hours continious light.

now saying all that it dose happen over time YES. in 30 mins NO (direct sunlight or fluro)

Very interesting delboy - there are several brewers on this forum that reckon a beer skunks in just a minute or so of sunlight. i've tried putting a bottle in sunlight for 10 minutes & comparing to a nonexposed bottle & tasted no difference whatsoever. I put it down to my pallette; but maybe not from your info. Always wonderered how you could enjoy a beer out of a clear glass if skunking happened so fast h34r:

cheers ross

 

[winkle]

I won't have thought that 30 minutes in a fridge would do much since we are talking about a chemical reaction. I'd of thought that the reaction would be quicker in direct sunlight with warm/hot beer and the reaction time in a display fridge would be much slower. No that I'm any sort of chemist, and I've certianly had my share of skunked beers Bloody green bottles

 

[Vlad the Pale Aler]

The only experience I've had with skunking was while drinking outside LC in Freo and being entertained by Tony M.
Swore blind his beer was going off and engineered a Pint Pergola out of coasters over the beer to avoid skunking.
Did anyone get a pic?

 

[domonsura]

Always wonderered how you could enjoy a beer out of a clear glass if skunking happened so fast h34r:

cheers ross

Right on there Ross, me too........to tell the truth I reckon it's an over-exaggerated phenomenon. Clear bottles left in direct light for months, for sure, but I've never believed that it happens in 30 minutes or anything close.
I've done a few brews bottled in clear bottles, a year ago did one & I wrapped half the bottles in black plastic and left the others uncovered, all in the shed where the light from the window was hitting the area for a few hours a day. They were in there for a month, and I couldn't taste any skunking at all from either. At the time I put it down to palette as well. But when I moved house I found some left I had forgotten about, and the uncovered ones had a definite funny taste, but the wrapped ones were fine. They were sitting there about 6 months all told, so not sure exactly when it happened, but it wasn't there at 1 month.

 

[reVoxAHB]

Hey, thanks guys for the speedy replies.

Choosing to err on the side of caution (for a whopping $2.95), I've mounted my previously exposed bulb (as heating element) into a Terracotta pot, to eliminate or prevent light strike.
Here's the final result:

I started by carefully drilling out the top of the pot, mounting the assembly so that the bulb is snug:

As heat rises, I chose to mount the pot in the bottom of the fridge (my previous assembly was mounted in the top corner, and I could faintly smell plastic and can detect slight warping in the roof after 10 minutes of usage**).

I was next concerned that the fermenting vessels would be sitting just centimeters from the top of the heated terracotta, and could potentially give my yeast bed a very high, direct heat hit so boiled a couple of SWMBO's garden pavers (she'll love that!), wedging them between two reversed fridge shelves. The hope is the pavers will take the direct heat and distribute it more evenly:

In action (shot using no flash with open shutter to capture leaking light):

I can more than live with this low level of leakage, based on the advice and opinion in this thread thus far.

Cheers again all :beer:
reVox


**Before using the terracotta pot as solution, I wrapped the metal grill (w/60W bulb) in aluminum foil, effectively boxing the light. It became so hot that within 10 minutes, the new bulb blew :excl: So I rewrapped just the bulb itself and again, so hot could smell plastic, etc. This may have worked fine had I simply relocated the grill/bulb to lower area of fridge. Overall, wasn't comfortable with bulb wrapping/masking.

 

[domonsura]

Well thought out and executed...might have to do something like that this winter if i want to brew ales

 

[Darren]

reVox,

Where aboutsare you located to need to warm your fridge at this time of year?

cheers

Darren

 

[reVoxAHB]

Always wonderered how you could enjoy a beer out of a clear glass if skunking happened so fast h34r:

exactly! Well said.

Well thought out and executed...might have to do something like that this winter if i want to brew ales

Thanks mate! A bit of trial and error and AHB'er ideas go a long a way, I reckon. I'm not on any sort of budget, but I especially like not having spent any money (ok, $3 and a few parts I had around the house) for this, a workable solution.

reVox,

Where aboutsare you located to need to warm your fridge at this time of year?

Good old Melbourne. My fermentation fridge has been dropping as low as 16C at night, and then back up into the 20's the next day. We had several very cold days about a week ago (in the mid-teens) and bingo, back into the 25C-27C range.

I use a FridgeMate and manually swap between heating and cooling, as required. At this time of year, I mostly need heating at night. Currently fermenting an American Wheat+3056 with optimal fermentation recommendation of 19.4C. This setup keeps me pretty darn close.

 

[warrenlw63]

Choosing to err on the side of caution (for a whopping $2.95), I've mounted my previously exposed bulb (as heating element) into a Terracotta pot, to eliminate or prevent light strike.

Love your work reVox!! Great contri.

Edit: Good to see another lightstrike thread has moved along with the standard predictability.

Warren -

 

[reVoxAHB]

I've fermented in glass carboys for years with an uncovered light-bulb in winter.
Never noticed a problem with light strike whatsoever.

This (your experience) was enough for me, to just leave my setup as it was. However, with the bulb more or less melting the top of my fridge, I really had to move it.. and since I was going to the trouble of relocating including extending the wiring, etc. just chucked it into terracotta. Thx for the advice. It's interesting to note you never detected any light-strike/problem whatsoever. I would've assumed otherwise, but of course that's why i started this thread, to learn more and stop making assumptions :lol:

The only experience I've had with light striking was when I worked in a retail bottle shop, some years ago. For display, we took several slabs of brown bottled beer and stacked them in a large spiraling pyramid, in our front window. The display was up for about 6 months. Varying degree of light hit those bottles throughout the day, including direct. I can't remember how or why we drank (or maybe sold) 1 of the 6 packs in the display. Anyway, it was definitely skunked. Noticeably poorer than our standard stock.

Love your work reVox!! Great contri.
Warren -

Cheers.

 

[Tony M]

Revox, I'd be worried that your plastic light fitting will get very hot in that pot and melt/distort/char or something. You need to drill a couple of vent holes in the bottom of the pot to let the hot air escape. (and the light. har har har.)

 

[reVoxAHB]

Revox, I'd be worried that your plastic light fitting will get very hot in that pot and melt/distort/char or something. You need to drill a couple of vent holes in the bottom of the pot to let the hot air escape. (and the light. har har har.)

Yeah, I'll be keeping an eye on the mainly ceramic assembly over the coming weeks. I've got a 40W bulb in there now- hoping it will be gentler than the 60W I was using with old setup. As the colder months creep on us and the bulb will be active for longer periods of time, I'm totally expecting to drill breather holes or similar.

A new battery has been installed in the smoke detector which neighbors my ferm fridge room, too :blink:

 

[warrenlw63]

Yeah, I'll be keeping an eye on the mainly ceramic assembly over the coming weeks. I've got a 40W bulb in there now- hoping it will be gentler than the 60W I was using with old setup. As the colder months creep on us and the bulb will be active for longer periods of time, I'm totally expecting to drill breather holes or similar.

A new battery has been installed in the smoke detector which neighbors my ferm fridge room, too :blink:

Revox

That notwithstanding you can buy a ceramic globe holder (Edison fitting) for around $15 with a cord attached.

Just go to any place that sells reptile equipment etc. I bought one for my warming cabinet. They're basically heat proof.

Link here

Warren -

 

[reVoxAHB]

Yeah, I'll be keeping an eye on the mainly ceramic assembly over the coming weeks. I've got a 40W bulb in there now- hoping it will be gentler than the 60W I was using with old setup. As the colder months creep on us and the bulb will be active for longer periods of time, I'm totally expecting to drill breather holes or similar.

A new battery has been installed in the smoke detector which neighbors my ferm fridge room, too :blink:

As I've had this setup in continuous use for well over a month, I thought I'd report back that all's good! Not a problem in the world. The heat that's kicked out is relatively low and even (settled on 40W). Probably didn't need the pavers in there, but as everything's working well (as is) I'm not going to fix what ain't broke

I don't have exacting figures to provide in regard to heating times and of course, they would fluctuate with the change in daily temp, but I can tell you when it drops low enough to kick into operational mode, it gets me back to temp within 30-40 minutes by estimate.

The globe holder and ceramic top have been absolutely fine- no signs of charing or otherwise.

Thanks again everybody for the direction and advice that brought me here. My beer thanks you as well
Cheers :beer: