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Treacodactyl

Wine and sunlight

My house is pleasantly cool in the summer, but this does mean the fermenting wines take longer. I know people often place the demijohns on the window ledge or even leave them in the greenhouse but does the light not affect them in an adverse way? I know bottled wine should be kept somewhere in the dark while it matures but what about while it is fermenting? I could keep the djs in a box in the greenhouse if necessary.
Penny Outskirts

Re: Wine and sunlight

Treacodactyl wrote:
My house is pleasantly cool in the summer, but this does mean the fermenting wines take longer. I know people often place the demijohns on the window ledge or even leave them in the greenhouse but does the light not affect them in an adverse way? I know bottled wine should be kept somewhere in the dark while it matures but what about while it is fermenting? I could keep the djs in a box in the greenhouse if necessary.


I am absolutely no expert, but don't dark coloured demijohns help with this Confused
frewen

I've put demi-johns of fermenting wine on the windowsill in the past and had no problems.

I don't think I'd use the greenhouse as it may get too hot and have too much of a variation in temperature for the wine - especially in demi-john size. Larger batches of wine have more resilience but I still wouldn't risk it.

And as you say - I wouldn't put keep the finished article in the sun. Not that the finished article hangs around long. That's why I've started making wine again while I'm pregnant and on an alcohol ban - give it a chance to mature for a change Laughing
cab

A bit of sunlight for a while won't matter so much with a white wine, but be more careful with reds and anything that has a subtle colour. And be very careful that the wine doesn't heat up too much, I've had the occasional 'foam explosion' in the past and that's no good at all!
gil

Re: Wine and sunlight

Penny wrote:
I am absolutely no expert, but don't dark coloured demijohns help with this Confused


Dark DJs are good for maturing wine, but with a fermentation, you can't see what's happening in them properly.

Light from a lightbulb doesn't seem to affect colour or taste of fermenting wines (as far as I can tell so far from the output of the newish fermentation cupboard).

I'd have thought a greenhouse might be too hot / subject to temperature variation. Windowsill would be better, but if temp drops at night with clear skies, bring them into the room.
cab

Re: Wine and sunlight

gil wrote:

Light from a lightbulb doesn't seem to affect colour or taste of fermenting wines (as far as I can tell so far from the output of the newish fermentation cupboard).


Doesn't get to it anything like as much. Think a bit about the chemistry here for a moment.

Coloured chemicals, the ones that you've got in wines that turn it an interesting colour, are quite obviously going to do somethign interesting in light. Thats howcome they're coloured. Now, here's some rules of thumb; red light is best absorbed with something greenish, and blue light is best absorbed with something orange or reddish. Think of ultra violet light as being really, really blue and really energetic. Put a subtle red pigment, such as you get in strawberry wine, in sunlight and odds are it'll break. The energy from the UV light being absorbed has to go somewhere. Put that same wine in a box with a 40w or 60w lightbulb and you've not actually got a great deal of infra red light there, and besides the colour spectrum of those bulbs is kind of warm, its all a bit red. So odds are you'll be fine.

Quote:
I'd have thought a greenhouse might be too hot / subject to temperature variation. Windowsill would be better, but if temp drops at night with clear skies, bring them into the room.


Temp variation is almost as bad for wines than prolonged cold; the yeast starts to grow fast, then it slows down, and you get nasty bitter or off odours if you're not careful. So yeah, windowsill or indoors is better than a greenhouse, IMHO.
Treacodactyl

Re: Wine and sunlight

cab wrote:
Coloured chemicals, the ones that you've got in wines that turn it an interesting colour, are quite obviously going to do somethign interesting in light. Thats howcome they're coloured.


Why is it obvious? Certainly I thought some things are a certain colour in order for them to do a job so it is likely they might change, but other colours are there just to attract things so why should they break down? Also as your aim is to biochemically change something with yeasts and enzymes perhaps sunlight might change something for the better?

I don't mind the lack of colour it's mainly the flavour I'm concerned about. I suppose the answer will be to, one day, try a two gallon batch and place one in the dark and one in sunlight.

I think the heat would be something to worry about in my greenhouse, I know some people do put fermenting wines and beers in them but perhaps they have more control over the heat than I do.
cab

Re: Wine and sunlight

Treacodactyl wrote:

Why is it obvious? Certainly I thought some things are a certain colour in order for them to do a job so it is likely they might change, but other colours are there just to attract things so why should they break down? Also as your aim is to biochemically change something with yeasts and enzymes perhaps sunlight might change something for the better?


Think about light as energy, and think about colour as the bits of energy that aren't absorbed. So something white is absorbing very little light energy, and something black is absorbing most of it. Something green is absorbing most of the visible light but reflecting the green back, something red is taking in most of the visible light but reflecting back mostly the red light.

Now the energy thats absorbed has to go somewhere. In plants that are green, thats easy, it goes to fuel some funky biochemistry. In the black teeshirt I foolishly wore today, the light gets given off as heat (re-radiated at longer wavelength). In a wine made with, say, cherries, if you keep it in the light it'll go pale. The chemicals absorbing the light are taking in an awful lot of energy over a longer period of time and the chances of them breaking down as a result are much greater. You might call this 'photo bleaching'.

The interractions of yeast and light aren't anything like so much fun. UV will mutate it, and high UV will kill it. Most likely leaving it in the sun won't do much to the bulk population, but you'll kill some of the cells so there is something of a risk of getting an off taste that'll take longer to mature out. As for the rest of the biochemistry... Well, aromatic compounds are more likely to be evaporated off, so I wouldn't go for anything with subtle flavours.

Quote:
I don't mind the lack of colour it's mainly the flavour I'm concerned about. I suppose the answer will be to, one day, try a two gallon batch and place one in the dark and one in sunlight.


Could do. Or split a done batch into two sets of bottles and store some of them in the light.

Quote:
I think the heat would be something to worry about in my greenhouse, I know some people do put fermenting wines and beers in them but perhaps they have more control over the heat than I do.


Do you have a min-max thermometer? How hot is it getting in there?
dougal

Ultra Violet (in sunlight but hardly at all in lightbulbs, except specials for sunlamps or discos) is pretty good at fading colours.
I'm sure most folk have noticed this whether with upholstery, clothes, photographs, inkjet printout... and it can change the colour of your wine. Its not just a matter of bleaching the colour, it can make colours 'muddier'. Not an improvement.

Here's a suggestion. Put your demijon inside a black bin bag on a windowsill.
It'll get seriously warmed up. You might want to watch that none of it gets so hot as to kill the yeast - 55C ish? However, it will be screened from UV, and, 'in case of accidents' the mess would be contained...
Just a suggestion.
As another suggestion, because heat rises, the hottest air in a room will usually be near the ceiling. So simply putting DJs on top of tall cupboards can be enough to warm them up a bit.
gil

dougal wrote:
Here's a suggestion. Put your demijon inside a black bin bag on a windowsill. It'll get seriously warmed up. You might want to watch that none of it gets so hot as to kill the yeast - 55C ish?


AFAIK, 55C is more like the minimum temperature at which yeast starts to work. The ideal is 65, and its action starts to decline much above, say, 75. It dies somewhere above that.

Yeast is more heat tolerant than you might think (otherwise folk in hot climates would find brewing very hard). The main probs in the UK are achieving and maintaining a consistent warmth, which is what yeast needs to work really well.
dougal

gil wrote:
dougal wrote:
Here's a suggestion. Put your demijon inside a black bin bag on a windowsill. It'll get seriously warmed up. You might want to watch that none of it gets so hot as to kill the yeast - 55C ish?


AFAIK, 55C is more like the minimum temperature at which yeast starts to work. ...


Gil, I think 55 *F* would be a minimum, 70*F* very nice.

I think most brewing and baking yeasts die around 55 **C**... Smile
@Calli

Awww and here's me thinking this thread was about a perfect way to spend a Sunday afternoon Wink
gil

dougal wrote:
gil wrote:
dougal wrote:
Here's a suggestion. Put your demijon inside a black bin bag on a windowsill. It'll get seriously warmed up. You might want to watch that none of it gets so hot as to kill the yeast - 55C ish?


AFAIK, 55C is more like the minimum temperature at which yeast starts to work. ...


Gil, I think 55 *F* would be a minimum, 70*F* very nice.

I think most brewing and baking yeasts die around 55 **C**... Smile


Embarassed Embarassed You're absolutely correct, Dougal.
Treacodactyl

ExilesinGalway wrote:
Awww and here's me thinking this thread was about a perfect way to spend a Sunday afternoon Wink


Plenty of that going on as well. Very Happy I have a nice supply of bottles now and maturing djs full, some ideal for a summers eve.
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