The Fresh Loaf

A Community of Amateur Bakers and Artisan Bread Enthusiasts.

Starter Longevity/History

TangoDancer's picture

Starter Longevity/History

Does SD starter retain much environmental history?  I'm reading 'Sourdough Culture' by Eric Pallant and the author relays a story I've heard many times regarding 'this starter is X years old and came all the way from <fill in a geography>".  On the other hand, I've heard that after a starter is moved to a new locale, it begins to take on the yeast and bacteria of that locale and hence any starter that is older than a few months is really a reflection of the yeast and bacteria locally.  I think I read that last part in the Modernist bread book (and hence why professional chain bakeries like Boulanger refresh each chain's starter on a weekly or so basis with the new starter coming from corporate labs).  

So, I was just curious as to both any studies on that matter or even anecdotal observations.  I'm too new at this to have any observations as I've been making SD for about 2 years.  It just sounds like a cool topic.


Dave Cee's picture
Dave Cee

First off I would say this forum is fortunate to have scientists and subject matter experts who are very well qualified to opine on the biological nuances of fermentation and related processes, especially where it relates to sourdough culture. I am not one. My personal observations over 35 years make me believe that my mail-order starter's original regional identity was subsumed over time by its present locale. Then I happened to do a web search a couple years ago and discovered another factor (see image).

I live (more or less) between Fresno and Bakersfield, California. It has long been known that Bay Area air pollution comes right across Altamont Pass and then down the San Joaquin Valley. You can see it at certain times of the year. I wonder if the San Francisco yeasts (spores) come along for the ride. And if they would retain viability.

Best wishes. Dave

phaz's picture

To think a starter stays exactly the same over time would be a stretch. To think it is generally to mostly the same, not as far a stretch. Search the forums, there was a study showing sd starter from around the world were for the most part, populated by a narrow range of critters. And in the end, it makes bread, what me worry. Enjoy! 

BreadPun's picture

My beer-making experience and excessive reading about brewing yeast cultures has taught me that any yeast culture that is not handled and fed using sterile equipment and practices will almost certainly become contaminated with other strains of yeasts that arrive in the air and flour. About half the labour in any brewing operation is cleaning and sanitizing equipment to prevent contamination of the desired culture with wild ones. Unless you are storing/handling/feeding your starter with sterilized jars, spoons, and flour, it’s a neat certainty that it’s character will drift over time. 

You may also notice seasonal differences in your starter because the yeast type and load in the air will go through annual cycles. I see that at least one of the posters above is Californian, are there orchards or vineyards in your area? If so, when the fruit is ripe there will be an enormous amount of yeast floating around in the air. Enough that some breweries ferment their beer in the fall by simply leaving open to the outside air overnight to allow wild yeast to land in it, look up “brewing + coolship” or “spontaneous fermentation” if you’re interested. Grain (including wheat) is also rife with wild yeast, much of which will still be present and viable in the flour, especially on stone ground whole grain flours. Grain husks are after all the natural habitat for yeast that dines on flours.

For these reasons, I created my current starter using heat-sterilized flour and boiled/cooled water, and fed it with same until it developed to a usable state. My goal was to have a uniquely local culture. I now feed it with ordinary commercial bread flour so I know much of its micro biome is from the flour, but having captured the original from the air (under my pear tree in the fall) I can hope/pretend it’s authentically local 😆

idaveindy's picture

In a home environment, there is bound to be some "creep" in the make-up. But the changes can be minimized with a little effort.

Corporate entities can better control the inventory and consistent make-up of many different types of soursough.  Examples of companies that maintain long-term consistency of multiple sourdough cultures are:

My thoughts:

My current one I use most is the CFH San Fran culture. It has appeared consistent in terms of taste and performance for about 2 years.  My others were used about a year each and seemed consistent.

I have two going right now, the CHF San Fran, and a home-brew.  I keep them on different shelves in the fridge, and take them out and stir them and immediately return to fridge on alternate days -- odd days I stir "A" and even days I stir "B".  I feed them every 6 days, but not on the same day:  days 3, 9, 15, etc., I feed "A" -- and days 6, 12, 18, etc., I feed "B".   (That way, when I need to use a starter, it is at most 3 days since fed.)

By handling them on alternate days, and feeding even further apart, I hope to limit any airborne cross-contamination of spores.  

My kitchen trash can is intentionally small, so I empty it nearly every day. Therefore, ...hopefully...,  the discard has less time to sporulate and waft out of there back to the atmosphere.


Feeding ratio:  I feed the main starter (not talking "levain build" here) at 1:1:1 ratio by weight.  I think CHF says you could even go as low as 1:.5:.5.

Feeding brings in new yeast and LAB, but you can minimize it by:

a) Keeping the feed ratio minimized, thereby not overwhelming your existing yeasts/LABS, which hopefully allows them to out perform the newcomers. 

b) Use white flour, that is, bread or AP, and not any whole grain, because while white flour brings some yeast/LAB, the bran surface of whole grain brings more. 

(The exception being when your starter has become weak and you want to boost it with newcomer yeast/LAB and enzymes from whole wheat or whole rye. But in this case, you've already lost either the strength or constituent flora of your original starter anyway.)


Container and utensil protocol:  If you hand wash containers and utensils, drying them with a dish towel that hangs out in the open can transfer spores and bacteria.  I dry sourdough starter containers and utensils with paper towels when I wash them.


Grain mill dust:  If you mill flour in the kitchen, that might create fine airborne dust that might carry yeast/LAB from the grain.


Backup, backup, backup.  When your starter is exactly the way you want it, dehydrate a big batch.  Do this on a semi-regular basis, triple bag it, or bag it and seal the bag in a jar, date it, store it.

Bon appétit.

JonJ's picture

There's Ed Wood who sells starters that originated from all over the world:

The mere fact that they can somehow keep the strains that they sell distinct is impressive to me. I doubt they're using a laminar flow hood when they're culturing them too, although they may be using sterilized jars and tools. I do wonder also if they use imported flours for their feeding.

The same is possibly true for the Puratos sourdough library in Belgium, although in their case I do think they keep a dedicated supply of the appropriate flours to feed each starter.

Edit: must confess only read Dave's comment now, apologies for the duplication 

JonJ's picture

Ben Wolfe's lab at Tufts university also had this to say:

”The researchers are just starting to analyze the samples, but Wolfe hypothesizes that microbial variations will be determined more by whatever microbes are already in the flour than by geography. And a rough, preliminary analysis of a few samples seems to support that. Comparing East and West Coast starters hasn’t revealed any obvious differences so far. Another test shows that the microbes in different starters bought from King Arthur, a flour company, appear to be similar to one another.”