The Fresh Loaf

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Starter smells like rotten eggs

JamD's picture
JamD

Starter smells like rotten eggs

Hi,

This is my first post here.

I created a starter a couple of months ago and have made some lovely loaves from it. Unfortunately a few days ago it started smelling like rotten eggs after it had doubled in size, stirring it an popping the bubbles produces a very pungent rotten egg smell.

After doing some research it looks like there is bacteria in the starter causing the smell, I went about trying to rebalance the yeast by creating a new 1:10:10 starter every 12 hours. After doing this for 3 days though the starter would double in size but the egg smell is still just as bad. I'm at the point where I think I might need to create a new starter from scratch as I don't appear to be able to rectify this one.

My last idea is to leave the starter a long time with no food to go very acidic in the hopes this will kill the bacteria.

Does anyone know how I might go about fixing this problem?

Here is some info about my starter and process:

  • I use 50/50 white wheat and whole wheat, both organic
  • I use glass jars, a new one each time I feed, washed
  • I use tap water left out with the lid off for a few hours to let any chlorine evaporate
  • I've changed the container I put the water in just in case it was contaminated
  • I have not changed the flour I am using
  • The temp is about 20-21c, probably a bit lower overnight 

Thanks

SirSaccCer's picture
SirSaccCer

Hi JamD, welcome to TFL. I haven't heard of this problem with sourdough starters, but in once piece of kombucha-making literature (this one), a rotten egg smell is attributed to sulfur-oxidizing bacteria, as you say. The book in question suggests this is caused by using tap water with such bacteria present, and recommends boiling the water for >5 minutes, before it is cooled and used to brew. With that in mind, you could try feeding your contaminated starter regularly, using boiled and cooled water, to see if the smell goes away. But I think there is a good chance that the contaminating microorganisms are there to stay. My work in a science lab, where contamination and other weird stuff happens regularly, has taught me that it is usually less work to just start again from the beginning. You'll know better what to do from prior experience, and by using boiled (or filtered) water you'll minimize the chance of a second contamination.

Other users might have other opinions but I am happy to opine: when in doubt, throw it out!

JamD's picture
JamD

Hi SirSaccCer, thanks that is very helpful!

I won't hurt to boil the water first, I think I'll do that and keep the old starter so see if I can fix it over the next few days and at the same time start a new one, then I cover both bases.

andrewmb's picture
andrewmb

I have this exact issue. Did you ever solve it with yours? I usually boil my water and leave overnight but that wasn't helping.

 

Thanks!

JamD's picture
JamD

No, I never managed to solve it.

I got some new starter from a friend and started again but after a few refreshes it started smelling.

I ended up switching to 100% dark rye for my starter and haven't had any issues since.

The only thing it could have been was the flour itself I guess, I was using a 50/50 mix of white and whole wheat. I guess either one of them was contaminated either by me or it came contaminated.

With the dark rye I don't bother boiling the water and it always smells lovely and fruity. I keep it in the fridge all the time, take it out a day before I want to use it, let it warm up, make my levain for the bread, use about 10g of starter with 50g flour, 50g water, leave it out for a couple of hours then stick it back in the fridge.

Works fine every time.