Yesterday I decided to try to develop my own sourdough starter. I’ve gone and asked my sourdough-baking friends questions, read around on the internet (none of my cookbooks gave any advice, but then I’d not bought them for bread-baking at all), and gave it some thought. Then I got a clean jar, mixed up roughly 2 parts wheat flour to 1 part tap water, covered it lightly and left it on my kitchen counter.
Oh right, forgot to mention this before – I have also added a drop of the liquid collected on top of my natural yogurt in its bucket, to provide a good proven strain of lactobacillus, in case there weren’t any desirable ones around in the flour, water or on my utensils used to mix the starter.
This morning the starter did not appear to do much of anything, but I dutifully mixed and fed it and left it alone all day again. And lo and behold, by the end of 24 hours since the start of the experiment I have bubbling throughout the starter and a minimal rise. It is also beginning to smell less like wet flour and more sweet and yeasty, a slightly pungent and generally pleasant sort of smell. Apparently there is some sort (hopefully right sort!) of fermentation taking place, so I will feed it again in a little while to keep it happy overnight.
In the process of reading about how to make real sourdough, I have learned several things, the most notable one being that, apparently, most “sourdough” cookbook writers can’t tell find their behind with two hands and a flashlight. Not naming any names here (that’d be just uncivilized, not to mention unnecessary), but if your cookbook suggests using commercial bakers’ yeast for starting your sourdough starter, it’s one of the aforementioned cases. And here’s why:
Sourdough starter aka natural leaven is an interesting exercise in home microbiology. Of course, so is every fermentation process. Wait, what? Yes, indeed – all alcoholic beverages, all yeasted breads and all fermented dairy foods such as some cheeses, yogurts and the like all make use of microorganisms, be it lactobacillus in dairy cultures or yeast, or the combination of the two which is the alchemist’s stone of sourdough baking. In the case of sourdough starter, it is apparently a combination of acid-resistant yeast strain such as Saccharomyces exiguus (most of yeasts are not such, notably including bakers’ yeast, Saccharomyces cerevisiae) and a lactobacillus of some sort, which coexist in the acid environment maintained by the lactobacillus, and kill off any other microorganisms in the medium (competitive critters that the single-celled organisms are!), thus making it not “spoil” in uncontrolled fashion (i.e. not grow random mold or the wrong – and likely unhealthy – bacteria).
So bottom line there is that you want to let whatever yeast is on the flour to begin with fight it out with whatever other yeasts are there, and let the one most adapted to the acidic environment win eventually. Dumping a clump of bakers’ yeast in the starter to begin the process only muddles up the situation, as it may grow well for one or two days, and then die off because of lactobacillus proliferation. And in the meantime thanks to its quantity and the resulting head start it got, it’d outcompeted all those other yeasts that we want to be in the running. Not a smart idea in my view.
Anyhow, the point of the above is that one should not start a sourdough starter with the yeast sold for quick-fermenting breads, and also explains why it is not a good idea to use a starter that has not yet stabilized (read: in which the desired organisms have not yet had time to bloodily murder all competitors whom we don’t want there anyway).
One day down, nine to go till the first test baking. The excitement of kitchen-sink (literally!) biology never ends!