Sourdough Starter - Hows, Whys, Whats

[jackal10]

I think it mistaken.

The fruit pieces (if it includes the skin) can add some extra yeast, but there is already plenty in the flour and the water. The eventual bread dough doesn't have fruit in it, so introducing it into the starter doesn't really help get the right flour eating yeast/lactobacili symbiosis going. It may provide some early activity but if anything by starting out with fruit yeasts, means the flour yeasts have a harder task getting established.

Similarly adding sucrose gives early activity from yeasts that can digest it, but it is antagonistic to Candida milleri. You will get activity, but the starter will take longer to stabilise - essentially the sugar will need to be exhausted by the conventional yeasts, and the resulting alcohol sufficiently diluted.

Add sugar if you are going to add conventional bakers yeast later, and just use the starter for flavouring, but that is not true sourdough.

[oraklet]

Forget that last question - I found the FAQ from rec.food.sourdough that answered my question completely down to the minute details of wild yeast sourdough starters. You can read it here:

ftp://rtfm.mit.edu/pub/usenet-by-group/ne...rdough/starters

My sourdough starter is completely healthy and I'm ready to start baking.

Nanette

http://cookingincolor.blog-city.com

maybe it's because my english is poor, but i find the instructions in the link very hard to decipher. also, a bit different from jackal's.

so, i've started out 3 days ago with 1 c. flour and 1 c. water. by yesterday it started smelling sour, and i added the same amounts again. today it smells sour in a nicer way. was this wrong? i definitely don't want to produce sour bread.

and jackal mentions that the ready starter will be equal weight amounts of water and flour. at what time do you switch from weight to volume?

please forgive me all those questions.

[MobyP]

I have a q. for the sourdough fiends out there...

When I was feeding my starter 3 times a day, and it was growing so substantially, my major problem was how do I throw away the rest of it? Everyday it seemed I had a quart or two of grey, bubbling, disgusting slime to somehow get rid of.

My question is: what does everyone else do? Pour it in the garbage? Down the toilet? Smuggle it late at night into you neighbour's flourbeds? Exchange it with Guido, the local "merchant", calling it the "Old Gold of Tenochtitlan?"

Stories please...

[jackal10]

Forget that last question - I found the FAQ from rec.food.sourdough that answered my question completely down to the minute details of wild yeast sourdough starters. You can read it here:

ftp://rtfm.mit.edu/pub/usenet-by-group/ne...rdough/starters

My sourdough starter is completely healthy and I'm ready to start baking.

Nanette

http://cookingincolor.blog-city.com

maybe it's because my english is poor, but i find the instructions in the link very hard to decipher. also, a bit different from jackal's.

so, i've started out 3 days ago with 1 c. flour and 1 c. water. by yesterday it started smelling sour, and i added the same amounts again. today it smells sour in a nicer way. was this wrong? i definitely don't want to produce sour bread.

and jackal mentions that the ready starter will be equal weight amounts of water and flour. at what time do you switch from weight to volume?

please forgive me all those questions.

Sorry I meant equal amounts of flour, water and starter by volume.

What happens is that initially all sorts of bugs grow, smells awful (often like pear-drops from the amyls), maybe get green slime, then as you continue to feed and keep warm, the right yeast/lactobacteria begin to dominate as it is their preferred environment, the smell improves.

Any sourdough will be a bit sour - that is the point of it, and the high acidity keeps the nasty bugs out. Do't worry, the bread will taste fantastic, as most of the vinegar taste goes when you bake it.

Since the excess starter is just flour and water, it is perfectly bio-degradeable. I flush it down the sink diluted with lots of water, but you can put it on the compost heap, give it to friends for them to bake with, put it in the trash. If you can sell it as old gold, that sound like the best option..

[oraklet]

jackal,

last night i made a dough with my new starter. the left over starter is in a jar in the fridge like i believe you suggested:

"Use an old fashioned canning jar with a rubber gasket (like these). What you can do is remove the rubber gasket and the metal stuff so all you have is the jar with the glass top resting on it. This keeps things from getting into your starter and also allows the gasses created by fermentation to escape."

i think the starter smelled a bit of alcohol, but sure also of vinegar and yeast, and the dough seems to be doing fine. this is exciting!

should a new starter be fed more often than an old, well-stabilized one?

[jackal10]

Great stuff!

Ideally you should refresh your starter every day, and not refrigetate it at all. However if you are not a professional baker and using it all the time keep it in the fridge, and take it out the evening before you want to bake, refresh it, and refresh it again the following day.

That said, I'm lazy and usually only refresh once it on the day I'm baking, and that works for me. However it will be even more active if you do refresh it twice.

Starters, once established, are pretty tolerant. If you keep a regular routine, you will find your starter will adapt.

[oraklet]

actually i don't like refrigerators at all for any purposes, as the normal temperature of 5?C is a compromise, and is too cold for some stuff (like doughs, white wine, butter) and too warm for other (meat, fish, milk). perhaps with winter approaching, or at least fall, i could keep my starter on the countertop in the already noticeable colder kitchen.

[Pongi]

jackal10, when I got your answer about making a starter with fruit pieces, I had already done the first step, so I went on - although I was pretty discouraged.

Well, I have to say that apparently it worked fine.

The first day I smashed a small piece of pear and a small piece of banana (both without the peel), diluted them with warm water and kept aside for 24 hours.

The day after filtered the liquid, which had a slight alcoholic smell, discarded the solid fruit parts, and added 1 part manitoba flour and 1 part water.

24 hours after it wasn't bubbling yet, but looked somewhat "alive", and smelled nicely. I fed it, and less than 2 hours later it was bubbling vigorously and was doubled in size.

I can't say if the fruit thing works - it's likely that it could have been the same with a plain flour/water starter - but at least this system doesn't seem harmful...

I have already baked twice using my starter and I'm pretty satisfied of the results, although I actually need more practice and advice on the right starter/flour ratio and the best way to manage the proofing phase, which seems to last longer than with conventional yeast.

After 3 days at RT I refrigerated my starter for 36 hours. I didn't notice a significant loss of activity, as it started again bubbling as soon as I took it back out the fridge, but I had the impression that it tasted worse and had a bitter note. However, I made Pizza dough and it was fine.

I have a main question. Since, I suppose, homemade starters have not the same activity as they're not standardized, how can I judge how much active is mine? Can I determine which percentage of flour must be added on the basis of some criterion, something like " if the doubling time of your starter at 85° is 3 hours, add x parts flour to make bread dough"?

Another question. If I keep my starter always the same way, feeding it regularly without environmental changes, should I expect any change in its features? Will it stabilize, and its effect will be more predictable?

Thanks!

Pongi

[oraklet]

while i'm writing this, i'm having lunch: my sourdough bread. it's got lots and lots of taste/aroma, which is great, and is quite sour, which is not so great. will it "stabilize" with time?

[jackal10]

Glad they work!

If you want your bread less sour, refresh the starter more often, and have less time for the sponge step. It may be that a high level of acidity has built up in your starter so it might help to do a refresh step but start with only a small amount of innoculant (a tablespoon full to a cup of flour).

You can also bulk ferment for a shorter time.

A starter will stabilise quite quickly - a few weeks - if you keep what you do to it the same each time. I don't know of any standard - if it raises dough for you OK, then it works. A lot of how the bread comes out is dependant on technique, rather than the yeast.

[oraklet]

i'll try refreshing it. thanx!

[mklynch]

We just did a complete kitchen remodel at home- new floors, cabinets, ceilings, appliances, windows, you name it. I do a lot of baking and am wondering if anyone has experience with how much time it takes - if any - to re-establish the wild yeasts?

[slkinsey]

What do you mean "re-establish the wild yeasts?" Are you doing a lot of sourdough baking? If so, do you start entirely from scratch every time, or do you maintain a starter?

[mklynch]

I don't do alot of sourdough. But when I make bread, I often start with a flour and water mix that I leave on the counter overnight. The next day it's active and I go from there. My counter tops aren't installed yet, so I'm not fully up and running.

[McDuff]

I'm not a microbiologist, and I don't pretend to be one online, but here's my take on wild yeasts floating around looking for bread to leaven.

When one nurtures a sourdough culture, one is encouraging the yeasts present in the flour itself to feed and multiply. That's one good reason to start sourdoughs with organic flour. There are ways to start sourdoughs with grapes, and the faint white blush seen on a grape is the yeasts. It's really no different than inoculating a petri dish with nutrient gel on it with a bacteria. Give them the right conditions, and the yeasts, and bacteria, already present on the flour itself, will wake up and start to nosh. Over time, the yeasts in your immediate microenvironment will predominate, but they are not responsible for kick starting your starter.

[slkinsey]

Actually, there are several mistakes here...

First, there are no yeasts or bacteria on grapes (or whatever) that are useful in a sourdough starter. Those yeasts and bacteria are evolved to live on grapes, not in the entirely different environment of a continually refreshed sourdough starter.

As for the flour, interestingly it turns out that they don't typically find sourdough microorganisms in the flour either... or in the air. The fact is that they don't really know where they come from. Some sourdough microorganisms have been isolated from the teeth of children, for example. Regardless of where you live or what is floating around in your kitchen, if you start with equal weights of flour/water and feed twice a day by removing 90% of the old starter "batter" and replacing it with fresh flour/water, you will develop a symbiotic association of wild yeast and lactobacilli adapted to living in an environment of continually refreshed flour and water -- otherwise known as a sourdough culture.

In terms of the local microorganisms "taking over" the culture over time... this can happen, but doesn't necessarily have to happen if the sourdough culture has a strong symbiosis and is cared for properly. Indeed, there is strong scientific evidence that many older cultures succesfully resist deliberate infection of competing microorganisms. There are many examples of people maintaining separate sourdough cultures in their homes (or laboratories) which retain their individual character over time.

If you already have a strong, consistent culture you are using and feeding regularly, you should be able to go right back at it. If you don't have one, I recommend purchasing one from Sourdoughs International or getting one from a friend.

[McDuff]

First, there are no yeasts or bacteria on grapes (or whatever) that are useful in a sourdough starter.  Those yeasts and bacteria are evolved to live on grapes, not in the entirely different environment of a continually refreshed sourdough starter.

I only said that to give the Nancy Silverton fans a bone..I think the grapes thing is stupid and cumbersome beyond belief.

I made my sourdough starter, or barm as he calls it, following Reinhart's formula in Crust & Crumb. And the process is no more than what you said, mixing and waiting, discarding and refreshing. He seems to indicate in his books that the yeasts and bacteria are present on the wheat berries. I believe him, because his method, elegantly simple, yields astonishingly good bread, better than what I could make up.

As far as culturing sourdough bacteria from teeth, I've read that.... scientists have been able to isolate specifically lactobacillus sanfrancisco from tooth tartar.

I suppose cultures kept in laboratory conditions will remain true, but left open on a counter in a well-used kitchen, with the windows open and the summer breeze wafting in, carrying in who-knows-what, unseen, to land gently on a percolating pot of sourdough mother...

I wouldn't buy a sourdough culture..they are very easy to make. And just out of curiousity, slkinsey, are YOU a microbiologist?

Addendum: page 70, Crust & Crumb, Peter Reinhart

"S. exiguus is a wild yeast that lives on plants, fruits, and grains. It is the white bloom on grapes, plums, and other fruit, and it also lives on the outside of wheat berries. S. exiguus is slower acting and not as aggressive as the commercially produced cerevisae."

The line "Actually, there are several mistakes here." really sets me free. In a kinder gentler world one might label them "misconceptions" or "fantasies", or "wishful thinking', but no... we have here "mistakes."

And you know what? They're not mine. There's a quote from a prize-winning cookbook author, widely regarded as an expert in this particular field.

Edited June 12, 2004 by McDuff (log)

[slkinsey]

No, I'm not a microbiologist... but I do know some people who are, and I have corresponded with a few on sourdough.

Anyway, as to the origins of sourdough microorganisms, here is what Michael Gänzle (not only a microbiologist, but a sourdough researcher) had to say in some correspondence that was posted in rec.food.sourdough several years ago:

274 I chose to write "natural leaven" because it is less awkward than "mixed

275 ferment cultured from the environment and sustained with repeated

276 inoculation."

277 **

278 "Sustained with repeated inoculation" is better than anything I was

279 writing to say the same thing. "Cultured from the environment" is certainly

280 true - L. sanfranciscensis and the yeasts must come from somewhere - but

281 somewhat misleading, as these organisms most probably do not originate

282 from the grain, or the flour. Marco Gobbetti, whom I mentionned earlier,

283 has been looking for L. sanfranciscensis on all kinds of Italian wheat

284 flours, and he has not found any. In every Italian dough "sustained with

285 repeated inoculation" you'll find L. sanfranciscensis to be the dominating

286 species, though. No other scientist has been able to isolate L.

287 sanfranciscensis from any other source than sourdough, but all sourdough

288 "sustained etc." contain this organism as the dominating flora. A possible

289 source may be the humans: there are all kinds of lactobacilli thriving in

290 the mouth, the intestines, etc. Hammes met a South African Microbiologist

291 who claimed to have isolated L. sanfranciscensis from the teeth of

292 pre-school children. The data is not published, so I don't know what

293 science is behind this claim. But, wherever L. sanfranciscensis comes

294 from, it most probably does not come from the flour. (That's comment No 4)

Lines 278-294 are from Gänzle. Also from the same source we have:

335 The yeast and bacteria in natural leavens are considered native or wild

336 because the cultures are started with organisms recovered from

337 environmental surfaces,

338 **

339 The fermentation starts with flour microorganisms, but - see comment No 4 -

340 the sourdough lactobacilli and yeasts do probably not originate from the

341 grain.

Lines 339-341 are Gänzle.

And again:

350 The conditions under which a culture is developed and then maintained can

351 select out strains of yeast and bacteria that have special

352 characteristics, and the typical yeasts present in the air and soil in

353 different locations also vary somewhat in their properties and their

354 interactions with lactobacilli. This kind of co-evolution makes some

355 natural leavens remarkably stable when regularly maintained. The more

356 regular and consistent the maintenance, the more predictable the rising

357 power, microbiological composition, acid balance (acetic/lactic) and acid

358 production will be.

359 **

360 This is important (although I don't think that the yeasts from air and

361 soil do matter). But the consistency in maintenance is crucial (one is

362 allowed to err to one side or the other from time to time, though).

Lines 360-362 are Gänzle.

As for Reinhart's text... I love his stuff and agree that he is a "a prize-winning cookbook author, widely regarded as an expert in this particular field." But, when we speak of "this particular field" we speak of baking, not microbiology. There are dozens of books out there by highly respected bakers with bad information about sourdough in them. I have, for example, read that the acid produced in a sourdough fermentation strengthens the gluten, when in fact the opposite is true.

Anyway, speaking of Saccharomyces exiguus... there can be many strains of S. exiguus living in different environments. Just because some of them live on the surface of a grape does not mean that they will be able to survive in the radically different environment of a continually refreshed sourdough. A well-fed sourdough starter is like a cruel little evolution machine, and any microorganisms not already adapted to those conditions will not survive long. It is possible (and, indeed, necessary as a continually refreshed sourdough culture is not found in nature) that certain microorganisms will live in a similar-enough environment such that they are able to adapt and survive. But that does not describe the skin of a grape.

Besides, it's not as thought S. exiguus is the only, or even most common sourdough microorganism. The most common yeast, as it turns out, is Saccharomyces cerevisiae, followed by Candida milleri, C. humilis, S. exiguus and Issatchenkia orientalis. (Occurrence and dominance of yeast species in sourdough, Pulvirenti A, Solieri L, Gullo M, De Vero L, Giudici P., Lett Appl Microbiol. 2004;38(2):113-7.)

Finally, if I may comment briefly on the persistence of a well-maintained sourdough culture with a strong symbiosis. The yeast and lactobacilli, having evolved together for countless generations, have developed a symbiosis that confers a huge advantage over other microorganisms that might possibly invade and take over the culture. The culture microorganisms also have another huge advantage. There are around 10,000,000 to 1,000,000,000 sourdough microorganisms per gram of sourdough. Given this huge headstart, it is hard to imagine how it would be possible that yeast and bacteria floating around in the air and clinging to the flour (which Dr. Gänzle said he doesn't think are a significant source of sourdough microorganisms anyway) could arrive in such numbers and with such strength as to overcome these obstacles and "take over" a sourdough culture. Provided that the culture is well cared-for (not starved, not changed to a different food source, not subjected to extreme temperatures, etc.), old cultures have proven remarkably resistant to infection even following deliberate inoculations of commercial yeast. There are commercial sourdough cultures in Germany that have maintained the exact same microbiology ever since they have been studied (>50 years). There is ample evidence that it is, in fact, possible to maintain distinctly different cultures with distinctly different fermentation properties in one's home. I know, because I've done it. Now... if the culture is starved, if the food source is changed from white flour to rye or cornmeal, if sugar is added, if the culture is refreshed enough times ab ove 37C, etc. -- these things can create conditions under which the starter culture may be infected.

By the way, when I wrote "mistakes" I didn't intend it as a slight in any way.

[andiesenji]

Now... if the culture is starved, if the food source is changed from white flour to rye or cornmeal, if sugar is added, if the culture is refreshed enough times ab ove 37C, etc. -- these things can create conditions under which the starter culture may be infected.

Or, as I suspect may have happened to one of my cultures (purchased from Ed Wood), yeasts from a brewery about 1/2 mile from my home may have contaminated the culture.

This has always been a well-behaved culture which is distinct from other cultures I have and which I isolate by keeping them totally separate by a couple of weeks, running the kitchen exhaust on high before and after having the cultures open.

Anyway, during the last week of May the brewery pressure washed and vented their big lagering tanks (I could smell the beery aroma when outside my house).

At the same time, I refreshed this particular culture and made a batch of bread.

The dough rose rapidly and gained more volume than usual. On baking, the oven spring was much greater than usual, the cut edges of the slashes turned back in a curl and the inner dough pushed upward through the slashes.

The final product is not as sour as it should be.

I tried it with whole grain flour with added seeds and raisins and this also rose much more than it should have. The crumb is finer and the loaf much lighter.

It is good, just not the way it should be.

[slkinsey]

Maybe, yea. I always use a bit of my starter to inoculate a sponge (or whatever) that I use seperately to build the bread and refresh the starter in its storage jar. Other methods may be more susceptible to contamination.

[SethG]

Sam, it seems to me that, as the man says, the yeasts/bacteria have to come from somewhere. If it ain't the air or the flour, and I assume you don't think it's the water..... then what's left?

I have a hard time buying that humans are the source. Many of us have made starters from just flour and water, and I'm sure I'm not the only one who did everything I could to make sure the contents of my mouth and intestine had no contact with the starter. Many cookbooks encourage you to try to maintain absolutely sterile conditions at the beginning of the process. I'm not saying this advice is correct, but I am saying that I followed it and got a successful starter out of the deal.

This is quite a mystery. Maybe the theory of spontaneous generation wasn't so wrong after all!

[andiesenji]

Sam, it seems to me that, as the man says, the yeasts/bacteria have to come from somewhere. If it ain't the air or the flour, and I assume you don't think it's the water..... then what's left?

Many cookbooks encourage you to try to maintain absolutely sterile conditions at the beginning of the process. I'm not saying this advice is correct, but I am saying that I followed it and got a successful starter out of the deal.

This is quite a mystery. Maybe the theory of spontaneous generation wasn't so wrong after all!

Even where I live, in the desert, there are wild yeasts floating around. Many are beneficial, some are pathogenic. Fortunately the beneficial ones outnumber the bad boys by a large factor.

Fairly old cookbooks (from the 20s, 30s an 40s) advocate saving the water in which potatoes are cooked and mixing that with the flour, as the wild yeasts are "attracted" to it.

Some people make the mistake of putting their culture in too small a container. The best thing to use is a wide bowl which will expose the most surface of the culture to the wild yeasts.

Some strains are so strong that they will overwhelm other strains. You can take a mild sourdough starter, that has been maintained with little change over a period of years, to the San Francisco Bay area and within three or four months the nature of the beast has changed to that typical very sour culture that is dominant in that area and there is nothing you can do to stop it. I know several bakers who have tried...

There are as many ways to the goal as there are bakers. No particular way is right or wrong, it is what works for you that is important.

The one constant is that as long as the liquid that collects on top of the culture is clear or has a sooty tinge, it is okay. If it is pink, throw it out. It has been invaded by one of the bad boys.

If you see this, don't open it in your kitchen. Take it into the bathroom, open the container just enough to allow you to pour in some bleach. Let it set for 10 minutes or so, then add a lot of water and flush it.

If you pour it into your kitchen sink, the spores will "bloom" and be floating around in your kitchen.

[slkinsey]

Sam, it seems to me that, as the man says, the yeasts/bacteria have to come from somewhere.  If it ain't the air or the flour, and I assume you don't think it's the water..... then what's left?

Other envirinmental surfaces, including yourself. It's actually hard to say where it comes from. One can say, "it might have come from here" only when the microorganism is found in that place. So, while we can't exactly say where the stuff comes from, we can reasonably well say where it didn't come from. The human origin is merely a possibility, but I do find it very interesting that the only place other than in sourdough bread that L. sanfranciscensis has been found is in humans. That there has been extensive testing of Italian flour with no L. sanfranciscensis found, despite the fact that it is found in all Italian sourdoughs, is extremely persuasive evidence against the flour origin hypothesis.

I have a hard time buying that humans are the source.  Many of us have made starters from just flour and water, and I'm sure I'm not the only one who did everything I could to make sure the contents of my mouth and intestine had no contact with the starter.

First of all, human bodies are literally swimming in wild yeast and bacteria. I don't want to gross anyone out, but to make an example: do you know why it's recommended to wash one's hands after going to the bathroom? It's not because you might have pee on your fingers. It's because the entire area of your body from your belt to the top of your thighs is swimming with potentially nasty microorganisms like E. coli, etc. I make this example to illustrate the fact that just because something mostly lives in your mouth or intestine doesn't mean it doesn't end up in all kinds of other places. If you scratch an itch around your belt, you've likely got some intestinal microorganisms on your fingers.

Many cookbooks encourage you to try to maintain absolutely sterile conditions at the beginning of the process.  I'm not saying this advice is correct, but I am saying that I followed it and got a successful starter out of the deal.

As I said before, many (even most) cookbooks writing about sourdough contain tons of bad information when it comes to sourdough. All you're telling me is that you went to lot of unnecessary extra trouble sand ended up inoculating your starter anyway.

Even where I live, in the desert, there are wild yeasts floating around.

Everywhere you go there are tons of wild yeasts and other microscopic beasties living on just about everything. In reality, I don't think it's necessarily the case that the microorganisms are floating around in the air solo. Rather, they are likely living on the surface of tiny dist particles, etc.

Fairly old cookbooks (from the 20s, 30s an 40s) advocate saving the water in which potatoes are cooked and mixing that with the flour, as the wild yeasts are "attracted" to it.

This is ridiculous, of course. You can't "attract" wild yeast with potatoes the way you attract flies with honey. Microorganisms don't work that way.

Some people make the mistake of putting their culture in too small a container. The best thing to use is a wide bowl which will expose the most surface of the culture to the wild yeasts.

Again, this is based on the "from the air" hypothesis which is likely incorrect. I have personally had plenty of success starting a sourdough culture in a closed container maintaining the starter at 50 grams each of flour and water.

I thought I had already made this point, but if I haven't: It's not me saying that I don't think sourdough microorganisms come from the air or the flour. I'm not a sourdough microbiologist. What I am doing is repeating direct statements from someone who is a sourdough microbiologist.

I'd also like to make the point that people who focus on the wild yeast aspect of sourdough cultures are missing the point. The point is the lactobacilli, not the yeast, as the lactobacilli are the organisms that give sourdough its unique flavor, etc. The yeast are only important insofar as they are able to coexist and form a symbiosis with the lactobacilli.

Some strains are so strong that they will overwhelm other strains. You can take a mild sourdough starter, that has been maintained with little change over a period of years, to the San Francisco Bay area and within three or four months the nature of the beast has changed to that typical very sour culture that is dominant in that area and there is nothing you can do to stop it.

This will largely depend on the methods one uses in maintaining the sourdough culture. For sure, there are techniques some people use which work just fine in one area but will not work when continued in another. The "save a bit of the dough for next time" technique, for example, strikes me as a starter preservation technique that will not work very well in another environment. However, there are other techniques which have been met with great success, not only in the laboratory but also in homes. For example, this has always been my technique: I maintain 100 gram starter with 50 grams of filtered water and 50 grams of flour. When I make bread, I take out all of the starter I can get with a spoon and use that to build a sponge or inoculate the dough. Remaining stuck to the inside of the jar is around 10 grams of starter. To this I add 45 grams of water and 45 grams of flour to bring the starter up to 100 grams again. This dilution creates a pH of around 5.0 - 5.5 which the optimal environment for growth of the sourdough culture microorganisms per Gänzle. The jar is always covered. I have successfully maintained several entirely distinct sourdough cultures in my home for years using this method.

[SethG]

First of all, human bodies are literally swimming in wild yeast and bacteria. I don't want to gross anyone out, but to make an example: do you know why it's recommended to wash one's hands after going to the bathroom? It's not because you might have pee on your fingers. It's because the entire area of your body from your belt to the top of your thighs is swimming with potentially nasty microorganisms like E. coli, etc. I make this example to illustrate the fact that just because something mostly lives in your mouth or intestine doesn't mean it doesn't end up in all kinds of other places. If you scratch an itch around your belt, you've likely got some intestinal microorganisms on your fingers.

=

I'm not saying you or your source is wrong, Sam, but I'm still not sure I buy that humans contaminate the starter to get it going. It should be easy to test such a theory under lab conditions. Has anyone tried it?

[slkinsey]

Oh, I agree that it's only a possibility. The facts, as I have read them, are that we know a number of places where sourdough microorganisms are not commonly found and can rule out as a source (e.g., flour, water, air), and we know one place where sourdough bacteria has been found and should consider a possible source (humans).