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Sourdough Starter - Yeast overgrowth problem

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Roost 12's picture
Roost 12

Sourdough Starter - Yeast overgrowth problem

Hi,

about two months ago I decided to convert my liquid starter to a dough starter following these instructions. I have waited for 2 weeks - waiting the starter to "transform itself into a pasty, gelatenous substance" - before I refed it. That pasty, gelatenous state never happened. The surface of the starter dried out and made a crust with a soft core. Of course I had it in a covered container in the fridge at 5.5°C.

The third week, it started to smell like the way commercial yeast tastes (since commercial yeast has no smell that I know of), but it was that yeast smell which you immediately recognize. The smell rang a few bells for me so I decided to take some of the dough from the bread-dough I was proofing in the fridge (made with the original healthy liquid starter) and start a liquid starter again. It turned out to have yeast overgrowth as well (the starter, not the proofing dough)

So it has passed roughly a month since the problem has started and so far nothing seem to work. There is always a layer of yeast waiting for me which looks sort of like wrinkled curtain on my liquid starter and like white patches/dots on the dough starter. I tried:

  • (I did this 3 times and stopped because it had no effect) carefully scooping off the top layer, saving about a tablespoon of starter, washing the utensil with burning-hot water (but not boiling), and then putting the saved amount back into the cleansed utensil. Then I followed instructions on this webpage for "polluted starter" which work extremely well to get a vibrant starter but does nothing for the yeast problem. Here is the quote of instructions for your convenience:
    "1. Using 1 of the 2 tablespoons you rescued from the polluted
    starter, add 1 cup of 75[°F] degrees water, 1 1/2 cups all-purpose white
    flour, and proof for exactly 24 hours at 72-77 degrees.

    2. Refrigerate for no less than 12 hours, then repeat step 1.

    3. The proof-refrigerate cycle should be repeated at least once. Use
    your own judgement. If the starter was unusually dark or contained
    mold, I'd suggest doing it at least 4 or 5 times to be sure the
    offending organisms are eradicated. If the starter merely contained
    other baking ingredients, then a single 24-hour proof is probably
    enough. Each cycle is started by using 1 tablespoon from the last
    cycle."

  • then I tried starving it, thinking the yeast might die off since it wouldn't have any food to feed on. I should mention that when I said "starve" I meant waiting a day or two after a collapse.  It didn't change anything. Maybe I wasn't persistent enough but I just didn't dare to starve it longer. Somehow I thought neglecting it would make its health worse. Neglecting would be just waiting for sour smell (which I bet would never come).

So that's basically what I have been doing up to this point. It's better than what I started on but that's only because the original strain has been diluted so much (notice the above 1tbs method....1tbs in 2.5 cups of dough is diluting). When I say better I mean "the layer isn't as thick" and "the patches aren't as large/thick". The yeast layer, smell etc is still there. Help?

 

phaz's picture
phaz

I believe the pasty gelatinous state happens when food is exhausted. using 1tbsp starter to 2.5 chips flour, and then keeping it cool, it may take a month or more to reach that state. I think your starter is basically diluted too much. also, using a dough like consistency will slow things down even more. I'll keep a starter in the fridge, consistency is like a very wet dough - very thick pancake batter - and using something like a 1:.5:.5 ratio, s/f/w, I'll feed every month or so. using such a high food ratio you may be waiting a few months before you reach the state your looking for. I can only suggest stirring and kneading. stir up the liquid starter whenever your near it, and give the dough starter a little kneading here and there. this will mix up the bugs and food, allowing more to be consumed and hopefully speed things up a bit. I've mentioned in a couple threads to stir, then wait 6-12 hrs and see if things rise again. as long as it keeps rising, there is plenty of food, but it may not be available to the bugs. this is more likely to happen in a thick starter. so, try stirring/ kneading and watching until there's no or very little rise. then do a feeding. you may find that just mixing things up will eventually get the consistency you're looking for. oh, spots, I've never seen spots on my starter. 1 is kept on the counter, close to 6 months now, and the other is in the fridge. have never seen spots. you may have a mold contamination. with the yeast smell, you may no longer have the balance between yeast and lactobacillus needed to keep the bad buggers from taking hold. that may be a more pressing concern. anyway, good luck, I hope things work out in the end!

Mini Oven's picture
Mini Oven

like my long term starter when I plan to put it away for months at a time.  Only difference is that the instructions you linked list starter transformation as "one part water to two parts flour" which should give about a 100% hydration starter or one more like thick pancake batter.   Which I find doesn't correspond to the rest of the link's description of working in the flour, so it is closer to about 40 to 50% hydration.  The starter can sit for months at a time in the fridge and to use, the outside crusty layers are cut off and the inside can be soft or act much like commercial fresh yeast.  This does not mean it is packed full of yeast however and I find it needs a few feeds and warmth to get the yeast numbers back up to  raising bread.

I'm not sure what "yeast overgrowth" is.  I suspect it is something else, not yeast that you are describing.  Sounds more like a type of growth Debra Wink was telling us about a few months back.  Not dangerous or anything, just occurs now and again.  Sort of a fuzzy white lace on the starter.  Compare. See this post, scroll down:

http://www.thefreshloaf.com/node/24477/what-happened-my-starter-help

I think you switched to instructions for a polluted starter when no fix was needed.  At least not that big of one.  Thus adding to the confusion.  I think you just need to understand your starter to read the signs it is sending you.  Sounds to me like your refrigerated starter is low in the yeast department, high in the bacteria department and needs some help if you want to raise dough with it by itself.  

It needs to be fed regularly on the counter for a few days and allowed to rise and level out or start to fall before discarding & feeding again.  A few days should do it and keep track of the time it takes.  Keep in mind that with cooler nights, it may take longer, warmer days will speed it up.  With each large feed, it should be expanding more.

I have to chuckle to myself because many of the things you pulled on your starter make it better and stronger.  Ok, now what?  Would you like to boost yeast?  or do you want to just keep it in the fridge for a while?

One tablespoon of starter in 2.5 cups of dough is at first diluting (I would call feeding it or letting the older starter fight for life in the more healthy yeasty starter. Or I might call it adding more flavor bacteria to the dough.)  Sounds like the starter was fed  1:6:10  (S:W:F) or (starter:water:flour)   

20g plus 120g water and 200g flour   and this would normally after about 10 hrs. at 26°C  improve yeast growth.  

 

Roost 12's picture
Roost 12

The bacterial layer on top looks exactly like you said - fuzzy white laces. It looks similar to JimmyChoCho's but he has bubbly "hills" while I do not and my veins/laces are more pronounced. Also, he said his smelled normal (assuming that means typical soury/fermenty smell) while mine does not [smell like a normal starter]. I think the main reason, why I believe this isn't somekind of side-effecft of a super strong starter, is the bland smell. It's superficial with no complexity or depth. That's my liquid starter. Now, the dough starter sort of looks as if dusted by flour (i.e. no noticable growth pattern such as veins/laces) with stronger smell than the liquid one.

Ok, now what?  Would you like to boost yeast?  or do you want to just keep it in the fridge for a while? I don't know. What's the difference between them? I would like a strong robust starter which I could eventually keep in the fridge so I would need to feed it only once a week or so. :)

I will try this

It needs to be fed regularly on the counter for a few days and allowed to rise and level out or start to fall before discarding & feeding again.  A few days should do it and keep track of the time it takes.  Keep in mind that with cooler nights, it may take longer, warmer days will speed it up.  With each large feed, it should be expanding more.

and report back with results. Btw, is there any feeding ratio you recommend? Keep in mind I am using rye flour. The first couple of days after being freshly ground, I use wholegrain rye. After that I sift it through a sifter to remove about 1/3rd of flour weight for the wheat (I haven't measured that for rye). That should give you a rough idea of what kind of flour I work with. I never use commercial store-bought flour. I always buy flour that has been ground in front of me on a household stone-mill (those German/Austrian wooden ones...sorry, I don't know the exact manufacturer). I do that once every 7-10 days and keep the flour in the fridge so it doesn't age so fast.

Mini Oven's picture
Mini Oven

your beasties will love it whole.  Keep things small  10g to 50g both water and rye.  (1 to 5 is good for now but you can easily try a 1 to 10 ratio before you want to bake with it.  With cold weather you may find yourself using a larger portion of initial starter.  It does vary thru the seasons.    Pack into a narrow straight glass to observe.  Save the discard for other foods.  

Reduce the water a bit when you decide to chill and let the starter begin to rise about 1/3 before chilling.  It's good for a few weeks easy when stored covered.  Take small amounts out and elaborate once or twice before using.  I take out anywhere from 10g to 30g depending on the weather and temp. to feed with 100g flour.  I adjust my water according to when I want the ripe culture ready.  You have to factor in the flour temp as well as cold flour will slow fermentation.  

For long term storage take equal amounts (1 Tbs) of the more liquid ripe starter around 100% hydration and double the amount with water and add flour until a stiff ball forms.  Crumbly and just hangs together.  Roll in flour and bag it.  That will get you months of storage on the starter in the fridge.  

Roost 12's picture
Roost 12

First let me say it solved my "yeast bacteria" problem (thanks for help!!) but I am not there yet.

Ok, I was waiting to get a few healthy cycles before posting but your ratios threw me into a new area so I need to report now. :) First I did 2 feedings at 200% hydration (pancake-like consistency) at 1:1:2 (s:f:w). Two such feedings completely eliminated all signs of the "yeast bacteria". It smelled like a healthy starter. All that in only 9 hours (4.5h between those feeds).

Then I decided to try the 100% hydration....and it was like dough (1:5:5). If I turned the container upside-down the starter didn't fall down (that's how thick it was!). Granted, it was a very wet dough but dough nevertheless. It's also really hard to see when the starter is collapsing. There is no obvious clues. At 13 hours I noticed a small 1mm collapse on the sides (transparent container) but only on some parts....and then it stayed like that overnight. In the morning the collapse was more pronounced (2-3mm now) but the surface transformed itself into a skin with mild signs of bacteria overgrowth (30 hours since feeding...smell was ok-ish, of alcohol).

Maybe I was waiting for the wrong clues (sides instead of the top). How do you know when it's collapsing? 100% hydration makes a very stable dough-structure. :( It seems my problem is not being able to read dough-starter. That's how the problems originally started and how they now re-emerged (that skin hinted at the "yeast" but the smell was absent).

Mini Oven's picture
Mini Oven

Rye starter can be tricky that way.  Rye typically forms a dome and it stays up as the starter underneath collapses.  This is very different from wheat starters so I suggest lightly poking or breaking the top surface of your starter when it looks like it has peaked.  To study the starter try using a fork and gently pull back the surface skin and peek underneath to get a good look at the bubble matrix.  The bigger the bubbles, the farther along the fermentation.  

Roost 12's picture
Roost 12

Ok, I think I am starting to get this. It's like you said - rye makes a dome and it stays that way. The first sign of bubbles on top (tiny holes) usually appears 2 hours before collapse (side note: the dough should be put into the oven when it would look like that, right?). After that it stays the same until you notice the dome has leveled off. Ok, bubbles are bigger but you can't see that from the top. Fine-pointing the collapse is an art of itself and you basically need to guess its proximity. How am I doing so far?

Also, I read somewhere on this forum that enzyme activity isn't done after the collapse but since bread is more about rise collapse is sort of a turning point while the collapse doesn't matter for a starter. Something along those lines. It wasn't more specific than that but it hints at the idea the starter shouldn't necessarily be fed right before/at/after collapse. So when should a starter be fed to maximize all the vibrant goodness?

Oh, and no worries about the fork thingy. My starter container is transparent so I can see bubble activity through the sides. :)

Mini Oven's picture
Mini Oven

are also known as "pin holes" and form when the rye protein matrix can no longer hold the gasses from fermentation.

On a starter, pin holing is certainly a sign that the starter is active.  Bubbles will soon increase as the starter thins further and pop into one another on the the way to the surface often building under the crust.  They will first appear on a smooth surface as bumps (if the skin of the loaf is moist enough) and then break open.  On the bread, look for this bumpy surface to tell you that it is high time that shaped & proofed loaf was docked and in the oven.  A pin hole or two can also be baked but too many pin holes tells you it is maximum proofed or risen to it's fullest.  Docking at this point will collapse the loaf.  (big brick danger) (Try docking the rising starter where it doesn't matter if it falls or not.)  Better to bake a loaf before this peak happens when the loaf still has some gas catching properties left in it for a bit of exciting oven spring.

I'd say that you are getting the hang of things and doing a good job of it.  

Note how the aromas of the starter changes as it is first fed, later fermenting, doming and fully ripe.   You can taste it and poke it at any time to check on flavours.  Anytime the starter is rising and has upward movement, more flour can be added to extend the rise.  Once it starts to pin hole and loosen, getting more fluid in consistancy it is a good time to feed the starter.  To boost yeast feed at the first peak, to boost Bacteria, let it ferment longer and warmer before feeding.  I tend to work more on keeping the yeast fit and the bacteria tend to take care of themselves. 

Roost 12's picture
Roost 12

Thank you Mini, and phaz too for helping. :)