White dry "bloom" or dusty crust on starters
Hey - long-time reader but first post on these pages. Looking for experienced advice on my starters.
I've had a go at sourdough for a while now, but low level "around the kids" stuff with poor results. Picked up a bit last year and in lockdown, had a real spell and have got right back into it. My starters (I have two on the go) seem to develop a dry-looking powdery-looking white crust after a 24 hour feed. This forms on them both, even though one of them is 3 years old and never used to do that (used to just look wet until dark liquid gradually settled on top).
This new powdery looking crust bothers me only in case it's an issue (like I am cultivating a poisonous mould). But as such, I am interested if other people get this too, or know what it could be?
I had one starter on the go since about 2017, a rye base, maintained with 50% dark rye, 50% white bread flour at a rough 70% hydration. Did me fine, generally neglected between uses. I then got another starter going with a landrace wheat grain locally grown in Scotland which was impressive, vigorously bubbling after very little time. I maintained this for a while, and kind of shifted it to normal wheat maintaining as with the rye, 50/50 with white bread flour, and 70% hydration. I've got confused and mixed rye into the wheat and vice versa at times...
Not sure if that backstory helps, but any comments appreciated.
My guess is that your home is really dry and the part exposed to air is drying out a lot.
Do you live in a dry climate? What is the humidity inside of your home?
I use a mason jar with a plastic lid that is loosely screwed on, the top layer drys out a little bit, but not to the extent you are experiencing.
I retract my previous comment.
See the forum topic below for what I believe is happening with your starter (yeast bloom).
http://www.thefreshloaf.com/node/44955/weird-white-powdery-stuff-surface-my-sourdough-starter
I just realized you said the white powdery film is *new*. And, that last photo looks pretty powdery and not in a dried dough way.
Thanks for such a quick response and accurate answer. That thread looks really helpful. Will read throughout and consider options.
I wanted to return to log an update on my experience. You can see the photos of my issue with starter in my original post. The link provided by texasbak is I think the exact condition my starter suffered from. I tried s few things myself to recover. I'm not convinced the cause can by a lack of nitrogen. The issue occurred in two starters fed from different flours, one wheat, one rye. My attempts to look after and feed to recovery failed, and the smell of the white bloom is... Off. Not sweet, fruity, sour like fresh starter. More like cheesy.
So I bit the bullet and cleaned out both containers to start again with fresh flour. I got new a new rye starter going, keeping separate from wheat, but the issue re-occurred.
I blamed a lack of hygiene when cleaning out the container and did both, starting after a thorough clean, keeping both quite separate in case the flours were a source of some infection. On this attempt the starters developed well, no sign of white bloom or mould, and they continue to do me well. The flours have not changed, same bags.
As a slightly happy ending, the rye starter I had was going since 2017. Ditching it made me sad. But I remembered there would be some at the bottom of a sourdough beer brewed by a friend as a trial. I had a bottle of this remaining and quickly built a fresh starter up from this with white flour, presumably bringing at least some of the cultures and enzymes of the original! :)
Thanks again for the guidance on my problem!