The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

High ph in mother starter

C-brook's picture

High ph in mother starter

Hi there--I am new to this site, but already I am grateful all the advice this site's members provide.  This is my first posting, and I was hoping someone could help me with something I am seeing in my mother starter.

I've been using Reinhart's starter method from Artisan Breads Every Day, where a mother culture is built from  a seed culture.  Each sourdough bread uses the mother culture to create a wild yeast starter for the bread.

I understand that ph should be in the 3.5-4 range.  However, my ph is at 4.5.  Given this, my mother starter still seems to rise well after refreshment.  In fact, it doubles in volume in about 4 hours.  However, when I create a wild yeast starter for a bread from this mother starter, the wild yeast starter takes very long to double in volume -- typically more than 24 hours!  For this wild yeast starter, the ratio is 25% mother starter to added flour.  I suspect that the reason for this long rise time is the high ph.  

Am I correct in my suspicion?  Does anyone have any thoughts on what I should do about this?

Thank you very much in advance for your help!


Doc.Dough's picture

Excuse my ignorance, but I don't know how you (or Reinhart) defind a "seed" culture or how you convert a seed culture into a "mother" culture.  Tell us about your "mother starter".  What is your feeding schedule: refresh ratio, type of flour, time and temperature to important milestones (like when does it double and at what point do you refresh again)?  You didn't say how many stages of growth you plan to go through before you intend to make dough out of your starter.  Can you post a photo?

pH 4.5 is a bit high for a mature starter, or even one that you are using as the basis for starting a build. I would expect 3.8 down to 3.5.  The message I get is that you either don't have the right type of LAB in your goo, or something is inhibiting its growth.  Also, how do you measure pH? Paper strips, glass bulb pH sensor, or ISFET sensor?  And how do you calibrate?


C-brook's picture

Hi Doc,

Sure.  Reinhart describes seed vs mother culture as follows:

"Making a wild yeast starter involves two preliminary steps: preparing a seed culture and then converting the seed culture into a mother starter.  The seed culture cultivates enough microorganisms to get the ball rolling and is used to make another starter, the mother starter.  The mother starter will be the starter that you keep in your refrigerator perpetually.  It is kept at 75% hydration."

"From a portion of the mother starter, you'll then build what we'll call a wild yeast starter, only to diferentiate it from the motehr starter, as it is essentially the same thing.  The wild yeast starter will then be combined with a soaker or a mash for your final dough."

As suggested above, I started with the seed culture.  This is a 4 phase process:

Phase 1: mash (100%), whole wheat flour (100%), water (200%), diastatic malt powder (3%).  Aerate 3 times per day. Milestone: Time based -- 48 hours

Phase 2: mash (100%), whole wheat flour (100%), water (100%), all of phase 1 sponge (400%). Aerate 3 times per day.  Milestone: dough becomes very bubbly or 48 hours, whichever comes first (my dough was very bubbly at about 24 hours)

Phase 3: Whole wheat flour (100%), water (66%), half of phase 2 sponge (233%).  Aerate 2 times per day.  Milestone: dough is very bubbly and expanded (my dough doubled in size at about 12 hours).

Phase 4: Whole wheat flour (100%), water (66%), half of phase 3 sponge (100%).  Milestone: Sponge doubles in size (this occured in about 6 hours).

So everything was looking great.  I was proceeding through the milestones, and the dough was responding as described in the book.  However, at this point, I took my first ph reading using litmus strips.  The ph color indicated something between 4.5 and 5 at this point.  I was unsure what to make of this because it appeared as though the yeast was very active.  I decided to proceed with the next step in Reinhart's process, which is to make the mother starter.

Mother culture: Whole wheat flour (100%), water (76%), half of seed culture (33.3%).  Milestone: culture doubles in volume (this took about 6 hours).  

At this point, I degas the mother culture, and place it in refrigerator.  I also tested the ph again, and it was closer to 4.5.  

Again, proceeding through the milestones as prescribed, I decided to go ahead and attempt to make bread from this.  To do this, in Reinhart's method, I use a portion of this mother starter to create a wild yeast starter for the specific bread I am making.  In this case, I was making a white sourdough.  Wild yeast starter formula follows.

Wild yeast starter: Unbleached bread flour (100%), mother starter (25%), water at room temp (63%).  Milestone: Dough doubles in volume.  Supposed to take 9 hours, but mine took 26 hours!

Here's what I've been doing about this.  I have the mother cultures as prescribed in the refrigerator.  PH has not reduced since being in there (4 days).  I have also been maintaining the seed culture, which I set aside and decided to continue to feed when I noticed the ph was too high.  It gets fed 2-3 times / day, and I am on day 8 of this. It gets refreshed when it doubles in size.

2x daily refresh: Whole wheat flour (100%), seed culture (100%), water (75%).  

So that is where I am.  Below, I've posted a picture of the latest refresh on my culture.

Sorry for the really long note, but I wanted to make sure I gave you the detail you need to assess my situation.  I sincerely appreciate the help.


suave's picture

You have to understand that pH is a measure of acidity, and a acidity is a result of fermentation, therefore high pH (which means low acidity) can only be a result of insufficient fermentation.  Why does that happen?  If, as you seem to say, you mix "wild yeast" starter 4 hours after feeding the mother starter, then in all likelihood your starter is not ripe.  Doubling is meaningless since it depends entirely on how starter is mixed.  For some starters quadrupling is normal, other only rise by 50%.

A side note: measuring pH is about the most unreliable way of following dough progress.  Imagine you are ripping wood, and every once in while you stop, collect the sawdust, weigh and use the value to determine if you cut far enough.  That would be at about the same level.

C-brook's picture

Interesting thought on pH and volume expansion.  Clearly, I am new to this, but most things I've read suggest these are the two best indicators that you're progress is moving in the right direction or that you are sufficiently ripe.  

In your view, if not pH or volume expansion, what is the best assessment of ripeness?  

I provided a detailed account of what I've done above.  If you get a chance, please review, and share your thoughts.



MangoChutney's picture

A change in pH towards greater acidity is an indication of fermentation proceeding, but every time you add flour you are raising the pH.  The same thing can be true of your water, depending on the pH of that material.  Our water here is pH 7.8.  You can be keeping the pH higher than you expected to see while still feeding a vigorous fermentation.

I think probably most people here will tell you that the best assessment of ripeness in a starter is observation and experience.  To paraphrase an old joke about someone asking where to get off the subway, a starter is at its best just before its volume peaks and then starts decreasing.  You have to learn how your own starter behaves by watching it.  I can definitely say that just when you think you have it figured out, the season will change and you will have to adjust again.

suave's picture

Measuring pH is a relatively new thing, a fad I think, and come from lack of understanding of basic chemistry.  Also as far as I know, not a single reputable author suggests to do so, and for a good reason.  There're numerous problems with using pH as a handle.  First, it is difficult to measure.  Good universal paper will allow you to tell 4 from 5.  Short range paper may get you may be .3 precision.  But pH is logarithmic,  meaning that .3 is actually is a factor of two, and when you say 4.5-5 you are talking about values that differ by a factor of 3.  There're more precise ways of measuring pH, but they have their own issues.  Next problem is that acidity, strange as it may sound, is not a good indicator of acid content.  The reason for that is that fermentation produces two major acids and they contribute to acidity differently.  On top of that, dough, I believe, is buffered, which means that there's a range where it can maintain constant pH no matter what the actual acid content is.

I'll write you separate note on following the starter - right now I've gotta run.

Doc.Dough's picture


From the photo it is clear that you have yeast, but from your description of the process it is possible that you are short on LAB (which I find curious as I have never seen that condition before in a mature starter - though yours may not be in that category).  And you didn't specify at what temperature you were propagating your starter.  Your feeding schedule seems somewhat rushed (based on doubling rather than peaking).  In another thread I described an experiment I ran yesterday in which two different seed starters were used to initiate a refresh cycle that was done at 1:14:14 and run at 25°C. One seed was from a batch that had been refreshed 16 hrs previously and the other was 26.5 hrs old (the left overs from the seed that started the 16 hr batch). So two refreshes growing in parallel and acting like they came from the same batch of seed starter.  However, the older seed proved to have more active yeast in it and peaked first; the one with the 16 hr seed was just falling when the first one had mostly collapsed.  My conclusion is that between 16 hr and 26 hrs there was an increase in yeast population density, at least enough to enable the older seed to produce a more active result that peaked sooner than it's younger sister.

All of this is to suggest that you let a bit of your mother starter sit at room temperature (please tell us what that temperature is because it makes a huge difference in timing) until it falls back to somewhere about its original volume (but is still bubbly and not flat).  Now taste it.  Is is sour at all?  Very sour?  Just a little sour?  Does it smell sour?  Your tongue will tell you how acid it is.  You are actually tasting not pH but total titratable acid, and lactic acid at that.  What you smell is the more volatile acetic acid.  Trust you mouth before your test strips.  You are working with a batter and not a low viscosity liquid.  The only thing I use pH for is to tell me if I have achieved a post-refresh pH of >5.0 and thus am not in danger of suppressing the LAB population on a refresh to refresh basis.  Ten successive cycles of low pH (<5 after mixing) refreshes can deplete the LAB population density by a factor of 10 to 100 simply because the relative growth rate of the LAB and the yeast are the same when the LAB is in a pH 4.3 environment.  The yeast doesn't care what the pH is while the LAB stop reproducing at ~pH 3.8 but don't stop producing acid until they see pH 3.5 or so.

Now feed it with enough flour and water to allow it to grow for 10 to 12 hrs before it begins to fall back (1:13:13 @ 25°C; 1:6:6 @ 23°C ; 1:3:3 @ 20°C  - you can see how temperature dependent it is).  Now let it go for 12 hrs and see if it is close to peaking.  You can, with confidence, let it go for 24 hrs and still have a highly viable starter if it is close to peaking at 12 hrs. I am actually concerned that you are feeding it too soon and thus reducing the yeast population density every time you refresh - especially if you are operating in a cool kitchen.

If your starter is not sour at the end of 12 hrs, you may not have a bacterial population that you want and should continue to feed your starter, let it mature, then feed again, for a few weeks before you have a reasonable population of the right bacteria.  An alternative (and one I strongly suggest) is to mail order a bit of known good starter from King Arthur Flour so that you begin this adventure with a solid foundation of both good bacteria and yeast.  After six months to a year and 50 batches of bread you will know what to expect.  And at that point you can try making a new starter using Debra Wink's Pineapple Juice method.  I am sure Peter Reinhart ran the process successfully many times before he started signing his book, but the method you describe is not the one most widely recognized, just the one Peter describes.  There is a lot of bad information on the web and in books that is never effectively refuted, and most authors will not go back and post a "what I wish I had known when" blog after the publication of their manuscript and in the event of later learning.  In that vein, you should treat what I have written here as suspect until you verify it.  Trust what you do, not what you hear or read. Take it all with a pinch of salt. It took me 15 yrs to unlearn some "facts" that biased my mental model of how sourdough works and I try not to make claims that are not supported by peer reviewed journal articles or personal/reproducable experiments.  Luckily there are a lot of those, and they continue to push knowledge into the public domain and refine long held views.

C-brook's picture

You were all so helpful, and I regret that two weeks later, I am finally thanking you.  

Doctor: You were correct. I was overfeeding it.  I basically was feeding it every time it hit the doubling point in volume.  With your advice, I let it go for 12-18 hours, and it got more vigorous in its rise, and more sour to the taste.  I finally baked bread with it last week, and the bread was outstanding.  By the way, my room temp was 25.6 C.

I can't tell you how much I appreciate you taking the time to help me!