# Artificial Light Strike During Fermentation



## uncyp (16/8/10)

I have been reading an article on lightstrike from Beer and Brewer from last year. They don't seem to quote different types of light (Sunlight versus artificial lighting) and it's effect on beer. I currently use a 60 watt globe to heat my ferm fridge and it places a light source a few inches from my ferms. My first brews were pretty ordinary (style was good but taste pretty bad) I think that the light on the ferms may have affected my outcome as the beers (lager and pilsener) aren't improving in the keg. I know that I could maybe mask the light with a terracotta pot but this would need a major re-vamp of my ferm fridge. Does anyone know if light will affect beer through a fermenter?


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## Nick JD (16/8/10)

uncyp said:


> I have been reading an article on lightstrike from Beer and Brewer from last year. They don't seem to quote different types of light (Sunlight versus artificial lighting) and it's effect on beer. I currently use a 60 watt globe to heat my ferm fridge and it places a light source a few inches from my ferms. My first brews were pretty ordinary (style was good but taste pretty bad) I think that the light on the ferms may have affected my outcome as the beers (lager and pilsener) aren't improving in the keg. I know that I could maybe mask the light with a terracotta pot but this would need a major re-vamp of my ferm fridge. Does anyone know if light will affect beer through a fermenter?



I thought it was UV that caused it. Not sure an incandescent bulb puts out much if any UV. 

Just guessing though. Perhaps do a search on 3-methyl-2-butene-1-thiol.


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## sydneyhappyhour (16/8/10)

Nick JD said:


> I thought it was UV that caused it. Not sure an incandescent bulb puts out much if any UV.
> 
> Just guessing though. Perhaps do a search on 3-methyl-2-butene-1-thiol.


Yeah if its a 60 watt incandescent globe it should be fine, if its one of those newer energy saving fluro bulbs you may have issues as fluros emit some UV.


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## Nick JD (16/8/10)

sydneyhappyhour said:


> Yeah if its a 60 watt incandescent globe it should be fine, if its one of those newer energy saving fluro bulbs you may have issues as fluros emit some UV.



Thirsty will probably know what parts of the electromagnetic spectrum do the conversion of α-acids into STINK. All the literature I've read simply states, "Light", not UV - but UV is a lot more energetic, you can't get skin cancer sitting under a green light.


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## zebba (16/8/10)

Slightly OT, but using a fluro light seems to defeat the purpose to me. Incandescent are good 'cause they are inefficient - i.e. they throw out a heap of heat as well as light. Fluro's, being more efficient, wouldn't throw out as much heat.

Anyway, that's OT, so I'll go back in my hole.


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## sydneyhappyhour (16/8/10)

Found this paragraph info on a bottle manufacturer website:

"It is known that light at wavelengths between 350 and 520 nm cause a reaction in the sulphur containing amino acids
to produce a compound known as 3-methyl-2-butene-1-thiol (MBT) which gives beer a flavour that is considered
undesirable by most consumers."

Not sure where you would find data on the wavelengths given out by your normal type globes though.


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## jakub76 (16/8/10)

Here's a graph I picked up from a link on "How To..."



I have no idea how accurate it is but it does seem to put a 40W bulb in that problematic range.


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## Nick JD (16/8/10)

jakub76 said:


> Here's a graph I picked up from a link on "How To..."
> View attachment 40193
> 
> I have no idea how accurate it is but it does seem to put a 40W bulb in that problematic range.



350-400nm is UV. I'd guess most of the skunking would be coming from that end of the range - but a red or yellow filter over your incandescent bulb would sort it. 

Either that, or put a broken brown bottle on it! 

Then there's the half-opaque plastic of you barrel. My ambient beers show zero skunking and they are bathed in visible light during fermentation with much more wattage than 60W.


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## Tom909 (16/8/10)

Hey guys,

I keep turtles which need a fair amount of UV to stay healthy. I can assure that very little commercially available light globes produce any UV light at all - its a PITA finding ones that do! Also the few that do, the UV light is only good for about 10cm from the surface of the globe. The plastic will also block out most (if not all) of the UV anyway. Therefore you shouldnt have any issues with UV light penetrating your fermenters


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## manticle (16/8/10)

Which suggests that there is another issue making your beers not taste good. Have you tried leaving some beer in the sun until it's lightstruck to see if the flavours you are experiencing are the same?

What exactly is wrong with your brews so far and is it the same issue in each?


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## keifer33 (16/8/10)

Correct me if I am wrong but my logic works out to this.

2 lagers have been brewed. Lagers are "normally" lower in hops than say an IPA so thus there would be less alpha acids/ hop oils to allow 'skimming to occur'. Skunking creates a sulphur odor and taste which certain lager yeasts create as a by product. It'd have to be undrinkable or that the sulphur isn't decreasing over time?

I'm only new aswell but have done similar reading as the original poster. I hope I'm on the right track.


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## uncyp (16/8/10)

manticle said:


> Which suggests that there is another issue making your beers not taste good. Have you tried leaving some beer in the sun until it's lightstruck to see if the flavours you are experiencing are the same?
> 
> What exactly is wrong with your brews so far and is it the same issue in each?




It could be a bad case of Kit twang as it is kinda metallic and Bad Homebrewy - It was a BCraft Czech Pils and a Blue mountain lager padded out with LLME and both had a total of 30 gms of C-SAAZ. I just wanted to see if I can rule out light before I put 2 batches (stout and bitter) down tonite and tomorrow nite and continue using the light for my heat source. I will definitely treat my yeast better this time - I dry pitched S23 last time.


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## kelbygreen (16/8/10)

I put a jumper over my fermenters as I use a flood light and it gets hot. but it really isnt on that long. I am looking into getting a ceramic light used for reptiles, I havnt really looked but they do not produce any light so thought that would be good and they are also made for heating.


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## Nick JD (16/8/10)

uncyp said:


> It could be a bad case of Kit twang as it is kinda metallic and Bad Homebrewy - It was a BCraft Czech Pils and a Blue mountain lager padded out with LLME and both had a total of 30 gms of C-SAAZ. I just wanted to see if I can rule out light before I put 2 batches (stout and bitter) down tonite and tomorrow nite and continue using the light for my heat source. I will definitely treat my yeast better this time - I dry pitched S23 last time.



The isohops in the kits won't skunk - it doesn't convert I've heard. Kit beer can't skunk - how long did you boil the Saaz for? 

Light struck beer doesn't smell like sulphur, it smells like skunk spray ... there's a difference. A tiny bit of a sulphur whiff in a lager is kinda nice - S23 makes a fair whack of sulphur, so does 34/70. Perhaps try S189 as that is much less sulphury.

EDIT: if you wait a while the sulphur smell will fade as the beer matures.


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## Thirsty Boy (16/8/10)

Nick JD said:


> The isohops in the kits won't skunk - it doesn't convert I've heard. Kit beer can't skunk - how long did you boil the Saaz for?
> 
> Light struck beer doesn't smell like sulphur, it smells like skunk spray ... there's a difference. A tiny bit of a sulphur whiff in a lager is kinda nice - S23 makes a fair whack of sulphur, so does 34/70. Perhaps try S189 as that is much less sulphury.
> 
> EDIT: if you wait a while the sulphur smell will fade as the beer matures.



Isohops do skunk, it's only certain specialized forms that don't... Most kits will probably use the variety that does skunk.

A normal light globe isn't a bad problem for light strike... But it can make a beer go skunky given length of time for exposure, especially given it's so relatively close to the beer vs a light hanging in the middle of a room. It requires very very little MBT to be noticeable. Still, I doubt that it's the source of your problem, lots of people with light globes in fridges and not a wide reporting of light strike as an issue.

If you want to be sure, a black garbage bag over your fermenter removes even the possibility of the issue, or a towel wrapped around it... Don't have to shield the light, can just shield the fermenter.


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## uncyp (16/8/10)

Thirsty Boy said:


> Isohops do skunk, it's only certain specialized forms that don't... Most kits will probably use the variety that does skunk.
> 
> A normal light globe isn't a bad problem for light strike... But it can make a beer go skunky given length of time for exposure, especially given it's so relatively close to the beer vs a light hanging in the middle of a room. It requires very very little MBT to be noticeable. Still, I doubt that it's the source of your problem, lots of people with light globes in fridges and not a wide reporting of light strike as an issue.
> 
> If you want to be sure, a black garbage bag over your fermenter removes even the possibility of the issue, or a towel wrapped around it... Don't have to shield the light, can just shield the fermenter.



Thanks thirsty - a towel sounds the go - probably just poor brewing first time up I guess. I had been reading Beer and Brewer from Spring 09 and it didn't differentiate in it's use of the term light.


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## alford_j (16/8/10)

I would just put a tin can or drink can over the light bulb. Blocks the light but radiates the heat.

Alfie


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## jakub76 (16/8/10)

Alfie said:


> I would just put a tin can or drink can over the light bulb. Blocks the light but radiates the heat.



And burns the bulb out in no time.


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## Nevalicious (16/8/10)

jakub76 said:


> And burns the bulb out in no time.



Or melts the batten holder <_< 

I use an old mug over my globe... I did this to avoid light strike and to radiate heat (only from what I read...). Are you guys telling me for sure that I dont need these? My method works and works well, but has a tendency to melt the globe holder (batten type - have heaps from pulling them out at work) No light strike??


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