KAF starter

MaryinHammondsport was heard to say:

Obviously, my starter is no longer identical to the little plastic tub of dough I received from the company -- it has grown its own balance of yeast and type of bacteria. So will yours.

Actually, that's not at all obvious.  And this is going to be long, so go get a cup of coffee or something.

I often hear the "your starter will change" expressed as, "will my starter change when I move it?" with its corollary of, "When I moved from St. Louis to Poughkeepsie, my starter changed, what happened?"

There are more old husbands tales surrounding sourdough than almost anything else I've been involved with, with the possible exceptions of high-end audio and brewing.

Dr. Michael Gaenzle of the German Cereal Institute studies sourdough starters and says he has starters that the institute has had for over 50 years that have not changed in that time.

Somehow, I can still hear someone saying, "Yeah, but my starter doesn't taste or work the same as it did before I moved!"

There are lots of factors at play here, so it's not as simple and straight forward a topic as you might find in a biologist's lab slants.

Before I get too far into the discussion, I'll preface my comments by saying that all the comments apply to a healthy culture.  And that many hobbyist's cultures are on the ragged edge of death.  Good culture maintenance is very important.

Almost all cultures, whether a hobbyist culture or a professional baker's culture are impure cultures.  There are around half a dozen yeasts and three or so lactobacillus strains that can make a viable sourdough culture.  Most of our cultures have many of these in them, but one strain of yeast and one strain of bacteria are dominant.  If we change how we handle our cultures, we can change which strains are dominant.  And the taste and activity of the culture can change.  Sometimes this is good, sometimes it isn't.

Changes in cultures, absent changes in feeding habits, are unlikely, for the same reason that most experienced sourdough practitioners discount the "starter from the air" theory.  If you look at the count of yeast and bacteria in a volume of air, and compare that to the count in a gram of flour, it's obvious the odds favor the flour being the source of the culture.  Dr. Ed Wood in his "World Sourdoughs From Antiquity" book recounts an experiment he did for National Geographic wherein he tried to capture an authentic Egyptian culture from the air.  He irradiated the flour so it would not have anything alive on it.  In a lower-rent fashion, a number of people in rec.food.sourdough tried to get local cultures by pouring boiling water over the flour to try to sterilize it.  In both cases, the experienced people went from nearly universal success at starting a culture to a very high failure rate.  This corroborates the idea that most cultures are started from the flour, not from the air.
 
Similarly, the yeast and bacteria count in an active starter is much, much higher than the count in flour.  A large part of the stability researchers, such as Dr. Gaenzle, report in cultures is because the lactobacillus bacteria produce a number of chemicals to kill would-be invaders.  The acidity of sourdough starter is just the front line of defense.  So, it seems very unlikely that a healthy starter could be taken over by the yeast and bacteria found in either the air or flour.

Now then, if you've been taking good care of your culture, what could make the bread made with it taste different?  Hunters prize boars that have been feeding on acorns - it gives the meat a great taste (or so I'm told - if you want to send me a care package, I'd love to try some!)  French farmers force feed their geese special herbs and spices to give the pate made from the livers of those geese special tastes.  Many nursing mothers report that when they eat this food or that, their babies no longer like mom's milk.  If more complex organisms change their taste, or the taste of things they produce,  based on what they have been ingesting, is it any surprise that yeast and bacteria would also change their taste, and the taste of the breads they produce, based on changes to their diet?

There are regional differences in flours, even when the brand name on the sack is the same.  Different flours taste different.  And it seems that yeast and bacteria notice differences we don't.

Try converting your starter from white to whole wheat or rye flour.  There are very rapid changes to the aroma and taste of the starter, well beyond what you'd expect from the changes in the flour.

A number of experienced sourdough bakers have said that the key to copying another baker's bread isn't getting their sourdough starter, it lies in finding out what kind of flour they are using.

So, if your starter changes, maybe you need to send back to friends who didn't move and ask them for care packages of your old standby flour.  Or just get used to the flavors that the flavors in your new home produce.

Similarly, I don't think that the starter that King Arthur or Sourdoughs International or the Friends of Carl changes after you get it - if you take good care of it - but I do think the taste can change.  And that doesn't mean that local critters took over the starter.

Mike