May 3, 2011 - 12:53pm
In the Dark????
ph_Kosel posted this link to Martha's Stewart's site, with the formula for Tartine's Country Bread.
A few of the steps (1,3, and 4) have you rest the starter and then the dough in a warm and DARK place. Why in the dark?
I've never heard before that the amount of ambient light would be an issue with levain or dough.
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Light should make no difference, but putting it in the dark (like in a cabnet or a box) would also keep it out of a draft.
Har har har! I think the light actually helps speed up the fermenting.
Yeast need sleep to rest up because they're fungal, have DNA and more closely related to animal than plant.
the yeastie beasties are less shy about "yeasty beasty reproduction" when nobody's watching? LOL!
Hi,
This is probably really dumb, but they use yeast in both beer and wine, and most of those come in dark-colored glass bottles (but not white wine from what I've seen). I have zero knowledge of brewing beer or wine, but is there some yeast-related reason why they use the dark-glass? I thought I heard once it was to keep it from spoiling or something, not sure what they mean (accidental over-fermenting?). Maybe keeping the beasties in the dark slows down the fermentation a little? Would be a good easy experiment to do.
Brown glass is used in beer bottles to prevent spoilage known as "skunking". When light hits certain compounds present in beer, IIRC hops compounds, there is a chemical break down that creates a smell that is quite familiar, hence the term "skunk". Beer bottled in clear glass have a chemical additive that prevents "skunking". It has nothing to do with the yeast AFAIK.
Hello,
I was curious about it a bit so I googled around for "light effect on yeast". Found a a couple of articles on nih.gov, "Journal of Bacteriology".
The first one from 1978 seems to indicate that yeast at colder temps (12C) exposed to cool flourescent visible light are inhibited, but I'm not sure how bright their measurements say. ("above 1250 lx"). But only yeast at colder temps were affected, so not sure why the Martha Stewart article would say, "Warm and Dark".
From the abstract:
"Growth rate, sugar transport, and amino acid transport of yeast cells grown at 12 degrees C were inhibited by cool-white fluorescent light. At light intensities below 1,250 lx, growth and membrane transport were only slightly inhibited. Above 1,250 lx, there was increasing inhibition of both processes."
"Cells grown at 20 degrees C were not inhibited by light intensities that caused complete loss of viability and membrane transport activity in cells grown at 12 degrees C."
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC222077/
This one from 1948 suggests ultraviolet light is bad for yeast.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1265446/?page=1
Editing to fix grammar and clarify: I'm not sure what the unit of measurement "lx" means, haven't looked into it, or can envision if that is "really really bright" or nowhere near as bright as a regular 40-watt socket bulb. :)
All about lux (lx)
Cheers,
Juergen
So, 1250 lx doesn't seem excessively bright for the fluorescent light.
I guess, if those studies are correct:
1. Don't keep things at cold temps with a lightbulb nearby.
2. Don't take your starter to the beach or leave it in direct sunlight (UV rays).
Found this about Lactobacillus Casei, who lives in mouth and gut - maybe the lactobacilli in sourdough are similarly affected by light ...
in that B2 (riboflavin) is decreased with direct sunlight. That's why we store our yeast and nuts out of direct sunlight. Glass would be a filter of sorts and so would plastic or curtains or a cloth draped over the bowl.
Not a bad suggestion "in the dark" but it does lead one to think completely in the dark. If anyone has problems with sour development and is working outside under the midday sun, then yes, it could be the sunlight robbing the dough of it's essential B2 vitamins.
When I set a dough to rise in a sunny window, the window glass is there and the dough is covered, but the warmth from the sun raises the dough more on the window side of the bowl. Never noticed if it was less sour.