Weird White powdery stuff on the surface of my sourdough starter
hi,
I was about to feed my whole wheat 100% hydrated sourdough starter and noticed that the top of the starter was almost entirely covered with some white powdery stuff. The starter is about 1.5 months old and has been doing fine when they were maturing outside the fridge and also after I stored them in the fridge. 2 days ago I took them out of the fridge and would like to resume a daily feeding routine on the counter for them. Up until the second feeding outside the fridge which was about 36 hours before my horrifying discovery about the white powder just now, the starter were all doing fine, no strange smell or look and can double its volume after feeding.
Attached is a close up snapshot.The dark spots in the pictures are air bubbles.
When I looked closely, the white power looks like lots of commercial instant yeast, but smaller.
Please help! thanks!
liming
Well, I am no expert by any means, but to me, that looks like fungus. Mold. As in--get rid of your starter and start over.
Black stuff on top is generally the alcohol liquid that develops--even though it looks bad. White dots? Yuk. Does it smell OK?
Your photo isn't quite clear enough to tell. Does it look like this?
http://www.thefreshloaf.com/node/24477/what-happened-my-starter-help
hi Debra, yes, the powdery stuff on my starter looks like those in the link you gave.
If that's so, then your instinct about it looking like yeast is a good one. That's what it is, and it's harmless. But it grows this way when nitrogen-deprived. The question is, why is there a nutritional deficiency in yours? In JimmyChoCho's case, it was caused by algae-contaminated water from his filter/pitcher. Algae consumes nitrogen. Is there any chance that could be happening here? If not, then possibly there aren't enough free amino acids being generated in your starter after those that are initially present in the flour are used up.
Amino acids also come from the breakdown of proteins. First by enzymes (proteinases) in the flour chopping the proteins into smaller pieces called peptides. Then the peptides broken into individual amino acids -- the building blocks of proteins -- by lactic acid bacteria (their peptidase enzymes). Both parts need to happen, so it could be inadequate enzyme activity in the flour, or perhaps, since the starter had been in the fridge, sluggish activity on the part of the bacteria. Also, acids from bacteria increase the activity of flour proteinases, so bacteria contribute in two ways.
Do any of those possibilities resonate with you? In any case the solution involves an adequate feeding regimen --- at least once a day with enough fresh flour in the mix. And if there's algae, then clean water and away from light as well.
dw
Hi Debra.
It is interesting to understand how this could possibly happen in a regular starter since there should be ample supply of nitrogen in a flour water medium.
Do you have any thoughts / insights?Only recently have I had the luxury to see this effect first hand when I converted my SD starter into yeast water. After leaving it for a few days my water medium developed a top veiny and very yeasty smelling layer.
Just thought I'd add my observations...
regards,
Michael
EDIT: Had I of read you more thoroughly I would have seen you already provided an answer to my question. Forgive me.
Hi Michael,
Yes, flour has sufficient nitrogen tied up in protein, but yeast need it broken down for them. Fruit has much less nitrogen, so it's not surprising that your sourdough yeast had trouble. Making yeast water with only fruit and water is a natural wine fermentation which is very different from sourdough, and the process involves different flora. Wild strains of Saccharomyces cerevisiae, the sugar-loving yeast (one of many yeasts present in the biofilm on fruits) rises to dominance because it is tougher and less demanding, nutritionally, than the others.
I have gotten it to revert to the pseudo-mold form in yeast water, but it takes a month or more for me. I let a jar of raisin water ferment, and then sit and age until the raisins sank, some time after which white yeasty spots finally began to appear on the surface of the raisins. It is believed that the pseudohyphal form allows yeast to attach to and penetrate substrates (like my spent raisins) to reach more nutrients.
Best,
dw
hi debra, thanks for your advice! I think your diagnosis is correct and I should have fed the starter more frequently since it has been refrigerated.
I have thrown away the starter anyway. but if i experience it next time, I will know what happens.
thanks
liming
I have occasionally seen this if I've neglected my starter. I normally remove the mold layer and use the starter beneath it. With daily feedings the starter very soon returns to its normal appearance and activity.