How bad is light during fermentation?

Ok, here I go again with my questions... so how critical is it to keep your brew in the dark? How dark is adequate? If I leave my carboy in the kitchen counter (no direct sunlight) for a whole day after pitching, will I have off flavors? Thanks.

 

I can't say for sure if that limited exposure will cause any problems. I doubt that it would. If you're worried about it, get a dark, opaque bag and put it over the carboy with the airlock sticking through. Or, find a box that will fit over and do the same.

 

It's probably not an issue, but why not just put it in its final fermenting place out of light?

The lightstruck issues that beers can suffer from only happen in fermented (or fermenting) wort, so the odds of yours getting lightstruck in indirect light right after pitching seem slim, but I generally don't take unnecessary risks unless I have to.

 

Then they're not unnecessary are they?



I always throw an old t-shirt over my carboys just to be safe.

 

Skunking takes direct UV, but why risk it? Never know how much reflected light it would get. Wrap it in a towel & that will also keep the temperature stable.

 

Skunking is a photochemical reaction. It only needs the presence of photons in visible light to cause the reaction. Blue light, and to a lesser extent green and a bit of near ultraviolet are the most damaging to beer.

Most wavelengths of ultraviolet light are not a concern because glass blocks them quite effectively (that’s why you don’t get sunburned in your car).

The brighter the light and the longer bottles sit in that light the stronger the skunky smell will be. Even dark brown bottles won't guard a beer from the bright fluorescent lights for very long.

The hop compounds that are responsible for making beer bitter are called isomerized alpha-acids. These chemicals, along with sulfur compounds found in beer, are also culpable in beer skunking. When light hits beer, it provides the energy necessary to drive a reaction that transforms the iso-alpha-acids into 3-methyl-2-butene-1-thiol. The “thiol” part of that name indicates that there is sulfur present. Sulfur compounds often have strong, offensive aromas. Skunks, have evolved the ability to produce this chemical, and use it for self-defense.

In a sense, the aroma of light-struck beer doesn’t just resemble skunk spray, it is skunk spray!

John

 

Sounds more daring and 007-ish my way. :rockin:

 

You don't ferment beer in the light more so for biological reasons, not chemical ones!!!

If any one has taken microbiology and learned of all the different ways to kill bacteria (and particularly yeasts!) one of the best ways is exposure to UV light.

The UV pretty much kills the yeast causing them burst or break open. And as you know when yeast dies you get off flavors!

We did a test (but with bacteria) We exposed a plate of Staphlo Cacus arueus (which is less reative to UV than beer yeast) to 60 seconds of direct UV light. They all died. All of them. Don't put yeast in any sort of light, they will die and the ones that survive are only survivng in the shadow of the dead bodies laying ontop of them.

On a chemical level there might only be 1 or 2 photo reactive compounds that affect the bear on a marginal level compared to the yeast.

When making anything with yeast, keep in a pitch black place.

 

I've got tons of black T-shirts and I just slip one over the fermenter and worry is gone. If it makes much difference I don't know but it only takes a second so why not?

 

But I don't have a single black T-shirt.

For the past 12 years, I've done my fermenting in a corner of the kitchen that is shielded from direct sunlight and fluorescent light. I dont "dress" my carboys, and I've never had a problem.

-a.

 

I've always put my glass carboys in a black plastic garbage bag, and it seems to work very well (at least I've never noticed skunking in any of my batches)

 

I ended up taking over a whole kitchen closet as my brew space. It's convenient on brew, rack, and bottle days, and no light gets in.

 

i use my robe/gown from graduation to cover my fermentor when its in process. the best thing my graduation has gotten me yet...beer.

 

Yeah, me too.

 

I always keep my carboys wraped in cloth in the closet. Quick, Easy, and no worries.

 

[QUOTE="Adrian Abascal, post: 188297, member: 6592"the ones that survive are only surviving in the shadow of the dead bodies laying on top of them.[/QUOTE] Post apocalyptic brewing. Cool! LOL

 

When I first started brewing, I had carboys out in the open in our kitchen that got a ton of natural light. There was no skunkiness that I could discern at the time and I liked my beginning beers, but who knows what I'd taste now. I didn't used to notice the instant skunk when drinking a beer in a glass outside, so take it with a grain of salt.

 

All visible light can both modulate respiration and induce oxidative stress in fermenting yeast. Even non-UV visible light has a significant impact on yeast metabolism. The blue/green wavelengths of visible light dampen the amplitude of the ultradian rhythm of the cell’s metabolic process and also its arrangement. Blocking visible light will allow the cells to maintain their natural and healthful metabolic rhythm. But keep in mind that fermenting creates its own heat. Unless your fermenter is located in a cold environment, don’t wrap your fermenter in thick blankets which will not allow this heat to dissipate into the surrounding atmosphere. In average room temperatures cover the fermenter with a thin but light-blocking material and keep the airlock in place as deprivation of oxygen will aid in metabolic phase resetting of the cells.

 

I use black plastic garbage bags as well as preventative measure. I have never skunked beer in a fermenter, but have skunked beer in beer lines. Before I got my freezer, I had a keg out in the garage with the clear poly beer line exposed to the world. Ended up just having to flush it every time I wanted a glass of beer. It tasted truly terrible, and it was obvious.

Reason 871 why I am extremely happy with my stainless bucket.

 

My trick to keep my kitchen-fermented beer from being lightstruck was simply draping a towel over the carboy but leaving the airlock uncovered. After the first incident where a glass was dropped onto the carboy by a clumsy adult, the carboy got moved elsewhere away from stupid, careless people.
Some of my batches have gone bad but never from being skunked. I despise skunked beer.

 

How critical? Not absolute. I ferment some of my beer in a ferm chamber which is dark...when I'm not opening the door to check how it's doing. Then light gets in.

No light is best, a little is probably not discernably noticeable (at least I never have), the best solution is to limit light as much as you can.

This is a "best practice:" No light at all. Now, we probably cannot achieve that, so the next best thing is to allow as little light as possible into the process. This is actually an excellent way to progress as a brewer: figure out best practices and keep trying to do them, and if you can't do them absolutely, move closer to them as time, money, and ability allow.

 

Does it matter? a lot of people like Heineken....lol

 

Light-struck beer is known to be poorly kept ... and yes, there's no accounting for personal preference.
...and yes, taste does matter. Many people tolerate poor products and I've bought my share of lousy beer over the years, but now there's so much good stuff to find or make, why bother with sub-standard foodstuffs?

I cover my glass carboys, use brown bottles, and would never drink old beer. Light lagers in clear or translucent bottles suffer badly from faults and OLD Heineken is one of the worst offenders. Knowing that, a lot of conscientious brew companies stamp a production time and date on beer for those who know what fresh beer is like.

 

You know what would be great (if it doesn't already exist)? Proper outfits, form-fitted, to dress those fermenters in so they can stay in the living room with the rest of the family, be proud. No more hiding in closets or wearing peasant clothing.

I do a plastic bucket down in the basement. My bottles are shelved and draped over to near pitch black levels.
I have no idea how careful I actually need to be but I won't experiment with that.

 

Now that is a very good comparison of the effect of light versus darkness on the beer.

 

Upon her first experience at age 83 with intentionally skunked beer, my dear late mother exclaimed that her glass of Heineken "smells like a Polecat" (Southern Country for Skunk). She was right.

 

One of these day's I'll find a clear bottle and fill it with an IPA then leave it in the sun for while, rechill it and see what the effect is. I heard of a local brewery doing this as part of an off flavor tasting event and apparently with their pilsner it only took 10 minutes to become noticeable. Hoppier beers are more affected as I understand it.

 

If you want to brew The Best Beer™ you must grow, harvest, malt and kiln your grains, then do all your brewing, fermenting, bottling, etc. in total darkness in a basement purged with CO2 wearing nothing but the finest leather trousers and a little blue bonnet.

 

that may be the 'good stuff', don't want to use a trademarked phrase...but it wouldn't be vegan, now would it! lol

and it'd cause green house gas too, with the sterile co2 flush...

 

When we moved ,I was of course very careful of how I prepped my brewing equipment , after all we hauled it 625 miles in a moving van. We had just had new carpet installed in the old house and had some carpet pad leftover, so just to protect my carboys I wrapped them ( I have a 6 and 5 gallon) in the scrap carpet pad , cut the bottom so it will actually stand and sealed the edges with duct tape then shoved the one into my 6 gallon bottling bucket. So , when we got here and I checked everything over , I left the padding on as a jacket until I brewed again. Since it is imperative to keep light out of beer at any stage ,I left it on during fermentation .It also insulates it from any sudden temperature swings . The top I keep a brown bath towel over ,I can lift it periodically to see progress,and just because I like to peek at my beer.

 

Can't for the life of me figure out why.

 

I make cider, prime and sweeten it. Bottle it with one in a plastic bottle to check carbonation level. When the plastic bottle is hard, I pasteurize. But because the plastic is clear, it is usually a couple days ahead of the tinted glass bottles.