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The Controversy Rages On….

There has been an ongoing controversy over whether a starter culture that you obtain elsewhere, is taken over by, or reverts to, the local microorganisms after you have had it for a while.

I asked Debra Wink that question and she said a stable starter would keep the original organisms intact if it was healthy.  I have heard many different opinions on the subject. However, there is one thing that keeps me from making up my mind about the subject and that is the tests I have done. Many years ago, I did time tests for different starters to see how long they took to proof.  See Starter Experiments.

I was recently challenged to test the San Francisco starter and the Northwest starter again. The theory was that they would have the same proof by now because I obtained my San Francisco starter back in 2006 and my Northwest starter back in 2004.


I have had them either bubbling away on my counter or dried these many years. I use the Northwest starter the most. A couple of months ago, I got the San Francisco bubbling away on my counter too. So I have been feeding and caring for the two starters side by side for a while. So when I was challenged to do an experiment on them this is what happened:

The night before the experiment, I fed both starters the same amount by ratio, 1:1:1.

Next morning at 8:00 am I took 2 ounces of each starter and fed it with 2 ounces of water and flour. After four hours they looked like this:

I did not mark the SF at 11:00 o’clock because it hadn’t moved.


By 3:00 o’clock pm the Northwest had more than doubled but the SF was still lagging behind. These are proofing times that I would expect from the two starters. The Northwest starter is around a six hour proof (the house was at 67F) I expect it to double in at least six hours. The San Francisco is around a ten hour proof and I don’t expect it to double after six hours.


By 4:30 the Northwest starter had peaked but the San Francisco starter wasn’t yet doubled. At 4:30 the Northwest Starter began to fall back. So it made it eight and a half hours before falling in.

By 6:00 o’clock the San Francisco starter finally doubled. That was ten hours after it started this test.

At 8:30 pm, the San Francisco starter was still going strong, that is over 12 hours after it was fed!!

This is a top view of the San Francisco still rising and the Northwest falling in at 8:30 pm (NW had started falling in around 4:30 pm.

This last picture was taken the following morning. You can see that the San Francisco did not rise anymore, but it hadn’t fallen yet either and that is 24 hours after it was fed! I noticed shortly after taking this picture that it began to fall in.

My point is that the two starters did exactly what they were supposed to do. The Northwest starter is a six hour proof starter and is used for most types of bread baking, it is the favorite of many bakers.


The San Francisco starter is a VERY long proofing starter and you can use it for the very long fermented breads, you know, the kind you are trying to get a real sour tang. If you don’t know how to use a San Francisco starter, it can be disappointing. You can see that at the seven hour proofing time, it was still sluggish, if you were trying to use it with an average formula for sourdough bread, you would have thought it was a bum starter.

So…. what do you think? Did they revert to being the same starter? Let the controversy rage on…….please give your opinon!



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  1. May 26, 2013    

    A nice experiment. What I found in different scientific publications is that the main source of bacteria is from the flour you use. Depending on the type of flour e.g. wheat, spelt or rye, different species are dominant and gave the characteristic behaviour and taste to the sourdough. These shifts in microflora will happen very quickly when you start feeding your sourdough with another flour (e.g. rye flour instead of wheat flour). Temperature will influence the balance of the bacteria and yeasts as well.
    But as long as you keep the feeding conditions stable, the mikroflora should be stable as well.

  2. ElviraElvira
    April 29, 2013    

    I agree with you!
    I maintain three different starters and after years they keep their differences such as different time of proofing and different taste.

  3. April 14, 2013    

    I don’t really know, I always thought that starter cultures slowly convert to the microbes that are prevalent in the local environment, from the air. Then Peter Reinhart told me it would be the organisms that cling to the flour that would, eventually, take over. If the flour is local, okay, but if it comes from Montana, it would be Montana microbes.
    I wonder a bit whether the rise of the two starters were not influenced by the fact that the SF starter had been dried and inactive before, and the NW was regularly fed and active. Whenever I revived a dried starter, it took significantly longer for it to become active.

    • DonnaDonna
      January 27, 2016    

      It was active when she used it…she revived it from its dry state before the experiment

  4. April 13, 2013    

    wow , thats a very imp. discussion , esp. as far as we are concerned in the defence circle, we move from one place to the other and i have seen my starter shift base and it was a challange for me to bring it back to its natural state…here in wellington.
    So am from that experience, where i believe the culture does take time to settle into the new environment… and if it successfully sustains itself… it reverts back to the properties exclusive to it … as mine did, though am just a home baker and no where close to your proffessionl expertiese on the subject,i offer my exp. nonetheless , love it completely ! For now baking is on hold becoz we are shifting base ! will experience this cultur and its behaviour in a new place again … for now its packing – packing and detoxying with Navraatri festival in India…

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