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Peter’s Blog, Oct. 1

Written By Peter Reinhart
Sunday, 30 September 2012 Peter's Blog

Here’s the first question that came, from Doc.Dough. He must be a doc, for sure, as it takes a little study to understand the question — but I’ll take a stab at it and then all of you can chime in with comments.

Over on TFL I see lots of people slavishly following very exacting instructions without understanding what the instructions are intended to convey. Perhaps Peter could attempt to articulate the difference between importance and exactness or in some way provide some useful guidance to set expectations a little lower with respect to the behavior of sourdough cultures in the amateur’s kitchen. There is the “you have to do it enough times to have seen it go wrong occasionally” method of teaching, and there is the parametric sensitivity derivatives analytic approach which is fine for the science crowd but pretty useless for the average home baker. Is there a happy medium?

I think the answer is both yes and no. Let me see if I can elaborate: there are dozens of legitimate ways of making and keeping a starter. I have offered to send a file on the subject to anyone who requests it (write to me at to make the request — hundreds of you already have), but the main thing to remember is that a starter is just a medium for the cultivation of wild yeast and lactic acid and acetic acid-forming bacteria. The speed of development and the creation of a hospitable environment for these micro-organisms is partly determined by temperature and also by what organisms are already living in a dormant state on the grain and, to some extent, in the local air.  The biggest mistake I’ve seen in recent times is that people abandon their starter in the early stages (we call it the seed culture stage) because they think it is dead, or it isn’t activating on the same timetable as described in whatever method they are following. Other errors include trying to jump start it with commercial yeast (which is too fragile to survive the acidic conditions and will die and then give off glutathione which wreaks havoc on the gluten), or thinking that their old “mother” starter is no good after sitting in the fridge for months so they throw it out.

It is true that an old starter will turn to mush in the fridge and is not structurally sound enough for using in a loaf, but it only takes an ounce or two of it to re-establish it in a new, strong, viable “mother” starter in a day or two since the micro-organisms are still viable even if the dough itself is spent and chewed up by the acids.

There are a number of theories floating around about why it seems to be taking longer for a new seed culture to get up and running, one of which I discuss in the file referred to above, but I’ve found that the best way to ride out the waiting period is to knead or stir the seed culture, at least twice a day, until it wakes up and starts growing and smelling acidic (starting at phase three in the process; again, this is all spelled out in the file). But the reason for this stirring/kneading technique — and this goes to Doc’s implied question about understanding functionality as well as blindly following instructions — is to prevent invading bacteria and molds from establishing themselves on the surface of the seed culture while we’re waiting for it to establish it’s own strong colony of yeast and bacteria cells. It’s all very dramatic when you look at the dance involved in creating the conditions for this cultivation and symbiosis between yeast and bacteria (usually referred to as LAB, since the “lactic acid bacteria” are the heroes of sourdough bread — at least the “good” bacteria are, the ones who are defending their turf against the moldy ones — along with the wild yeast). Again, too much to spell out here, and I’m sure there will be some counterpoint discussion out there that, I hope, comes in as Comments here. But it’s a start.

Bottom line: there is a lot of science involved in all of this but you don’t have to be a scientist or to know all the science to make killer sourdough bread and to make and keep a mother starter. But it does help to understand the functionality of ingredients and how they affect the drama.  There is a lot of folklore out there on starters, some of it true and some of it simply custom that just happens to work, but almost by accident rather than because of science and function (I’m thinking of things, spoken of as “rules,”  like using onion or potato skins or even wine grapes to get the starter going — yes the starter does work but not because of these things).  Like Doc.Dough asks, can we lower the expectations of needing to know all the science and make it accessible and easy? Yes.

Maybe this is the time to ask all of you, do you have any useful pieces of this puzzle to share that will make sourdough cultivation easy for amateurs or home bakers? Are there any myths you’d like to dispel or get clarification on? Scientists, this is your chance to build some bridges! Let’s get a discussion going….



When brewing beer, right after you’ve pitched the yeast, it is common practice to agitate the wort to work more oxygen into the liquid. Some even go so far as to get a aerator stone (used in fish tanks to oxygenate the water) and bubble air, or even pure oxygen, through the wort. In the later stages of fermentation, oxidation in the beer is a Bad Thing™, but what I’ve read on the subject is that early in the life of the yeast (particularly as they are get acclimated to their new environment) they thrive on the added oxygen.

For the seed culture I’ve always thought of the vigorous stirring twice a day as a means of working oxygen into the mixture for the benefit of the nascent yeasts. I have no scientific or objective experience to back up that thought (I haven’t tried running a fish tank bubbler through a young starter) but it struck me as a potential parallel.

Charles Edmonds

I can appreciate your comments about people abandoning their starters prematurely because they felt it was not living up to their expectations.

I have a great starter now (based on your guidelines from the BBA book).

However I found that it took much longer than my original expectations to “get there” (to the point where it behaved like recipe guidelines generally lead us to expect).

Overall I guess it was six or eight months before I was happy with it.

Now I can keep it in the fridge, pop it out and feed it equal parts by weight of flour and water and in a very short time it is very active and ready to go.

I’m glad that I had the patience to keep feeding my starter and going through the ritual. What I have today is just what I wanted it to be and was well worth the effort in the early months.

Jean McDonald

I keep thinking I should be more scientific about my starter, documenting exact amounts, times, temps etc., but since I mostly use it for 18th century reenactments, I have not.
After recently promoting my cheif apprentice to head baker, I am writing at least some written guidelines.
In a nut shell: When I plan to bake I get it out of the fridge about one day for each month it’s been ‘asleep’, then feed it 1/2 or less by volume flour and water twice a day. At some point after it’s fully awake, I feed it about an hour before I save some back for the next time.
As I have little control over rising times for baking in an outdoor clay wood fired oven, if I were to get to too scientific, and plan for certain conditions – the weather would fail to cooperate, and I’d be having to wing it anyway.
I do agree with Charles Edmonds That it takes several weeks to months to get the starter to be reliable or maybe for me to understand how it works!


As both Jean and Charles note, time isn’t always predictable, often because of other factors. They have both created work arounds that are effective for them and I would never want to mess with that. There couldn’t be other viable ways to do those work arounds, and I would guess that many of you have differing methods, but one key is to be consistent, whatever system you use. That’s one thing the micro-organisms seem to like. But even when going off a system there are still ways to bring it back to a healthy, reliable starter.
Okay, I was hoping for more tips but maybe we should move on. I’ll post again early next week to get a new topic going but feel free to keep your comments coming.


My sourdough starter has been working well for 3 years but I usually bake once or twice a week and I hate throwing away any. I refresh once a week with 50g starter, 100g tap water and 100g AP flour which is left overnight on the counter and then placed in the refrigerator until the next refresh. To make breads I use a 2 step process: mix 30g cold starter with 35g tap water and 35g flour and leave on the counter for 8 hours. Step 2 takes the refreshed starter and mix it with 150g of water and then 150g of rye or wheat depending on the type of bread I am making. This is left on the counter for 8 hours then I add bread flour and water and finish the bread making process. This method of refreshing allows me to keep very little starter, is very active in raising the dough, softens the bran in the whole grain flour and has great flavor depth. The down side is that it is not very sour and takes 2 days.

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