The Fresh Loaf

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The rate of starter/levain and it’s affect on LAB

DanAyo's picture

The rate of starter/levain and it’s affect on LAB

I’d like to understand the following. I can’t seem to reconcile these 2 beliefs.

1- If my starter gets too acidic, it can be remedied by a mega feed. A 1-10 ratio greatly reduces the acidity, at least according to smell and taste. The starter ferments 12 hr @ 76F.

2- I make my SFSD but using 2% prefermented starter. The dough ferments a total of 18-19.5 hr at 77F. The bread is sour.

How is it the starter is less acidic, but the bread is sour when both use a very small amount of culture?

I know the bread is mage very sour and I’m pretty sure the starter is less acidic. What am I missing?


texasbakerdad's picture

Thanks for the question, I enjoyed learning while doing some research to support my suspicion.

Making the following assumptions:

  • There is nothing else in your SFSD that adds additional sour flavor.
  • The 2% and 1-10 ratio (10%) sourdough seeds contain roughly the same percentage of acid.

The sour tasting acid producing bacteria doesn't grow linearly. It grows exponentially, then peaks once the preferred food is consumed. Maybe the additional 6-7.5 hours in the SFSD is enough time for the SFSD bacteria to overtake the 10% mega feed in acid production. That would be my guess.

If you wanted to test my theory, you could take your 1-10 ratio mega feed and see if it is more sour after 18 hours.

Here is chart depicting the exponential growth of bacteria...

From this article, which does a good job explaining the process behind yeast, bacteria, and SFSD.

andythebaker's picture

search the name Debra Wink, who's the authoritative font of knowledge on this subject matter.  she's amazing.  i've read through her explanations several times and still struggle to understand it fully.  it's quite fascinating though.

here's an article to get you rolling.  there are a few others.

happy reading.


DanAyo's picture

I’ve read that article many times, but I don’t think I’ll ever completely grasp all of it :-)


dabrownman's picture

over 12 hours at 76 F the final acid load in the levain will drop the pH into the 3's most likely.  If you use that to make bread and let it ferment for 19 hours on the counter, it too will have a low  pH and you will get a sour  bread. 

To get a less sour bread you need to follow Chad Robertson's sweet levian method.  Refreshing it several times over a 24 hour period and then using it young about an hour,or an hour and a half ,after the last refreshment to add to the dough.  Then about 4 hours of counter work and BF and then 2 hours final proof.  7-8 hours from mixing to into the oven.

You are doing everything to get a sour bread instead - a it is working.  Your method makes a much better bread by the way.

Happy baking Dan 

DanAyo's picture

Am I correct to assume that huge feedings (1 part starter to 10 parts flour) during a 12 hr cycle will reduce the acids in a starter? That has been my experience. If that is the case, how do I reconcile using a small (2% ttl flour prefermented) to produce a very sour bread?

There seems to be a contradiction comparing one experience with the other.


”inquiring minds want to know”

Mini Oven's picture
Mini Oven

It's a matter of bacteria leapfrogging over the yeast production as yeast activity appears to slow down..

 A large feeding of 1 part starter culture to 10 parts flour will produce a mild starter in the beginning of fermentation up to the first peaking of the starter from yeast growth (provided there is a good growth of yeast in the starter culture.)

The high pH (or big acid drop) happening when flour and water is added to the starter is an indicator to the bacteria to crank up bacterial numbers for self preservation.   As the newly fed starter is expanding with yeast growth, that is the time to transfer the starter into a recipe (or perhaps bake it) before the bacteria numbers get too high.  Bacteria will keep multiplying until it is acid enough to protect itself (and the yeast) from invading organisms and it will taste sour.  Sometimes this sour tasting raw product will transfer to the baked product and sometimes not.  It depends on the bacterial makeup of the culture and how it is fed, temps etc.