In the last Release the Yeast we talked about how yeast does the work that eventually gives us alcohol; this time we’re turning our eyes to the other staff of life – bread, more specifically sourdough bread. Funny thing is, sourdough cultures aren’t just exclusively used for breads and bread products like pancakes and biscuits; you can conceivably make beer with them too.
So what is it?
Sourdoughs are symbiotic relationships between wild yeasts and a lactobacillus bacteria; one such is named Lactobacillus Sanfranciscensis, for its discovery in San Francisco — the spiritual home of modern sourdough. The yeasts provide the leavening action — or puff — to the dough. The sour flavor is the result of the growth of the bacteria, and its acid production. Different lactobacillus strains produce different levels of sourness, some like San Francisco’s are very aggressive, others — like the Parisian strains — are much more mild in character.
In antiquity, all breads were sourdough breads. Most anthropologists believe that the first leavened breads were baked in Egypt. You can imagine how this was discovered, unused flatbread dough suddenly rising with the breath of the gods out of nowhere, that was then baked and deemed divine in flavor and texture. Not until yeasts were actually isolated and then made widely available did humanity know how to make a bread that wasn’t the result of a yeast organism captured in the wild and then cultivated as sourdough.
How do you get one?
Making a starter is actually pretty easy. There is yeast already present in a bag of whole wheat flour. That’s not to say that you can simply add water, knead and let it stand for a few hours and expect to get the same kinds of breads you might produce with a package of commercially available baker’s yeast. It takes a good bit longer to encourage the kind of action you might expect.
To begin, you’ll need a vessel to put a starter in. Traditionally, ceramic crocks with lids are used; metal vessels are not recommended, afterall you are encouraging the production of acids which could react with the metal. I’ve actually used plastic with no unfortunate results. It should be small enough to fit in the refrigerator without taking up too much space, but big enough to accomodate a growing, expanding starter.
Once you’ve chosen a vessel, get a hold of some flour. I prefer whole wheat flour for starter making, as the more coarsely ground a flour is, the more yeast particles are likely to be found on individual grains. King Arthur makes an unbleached, whole wheat flour that I’ve had good success with. Next, add some water, maybe a little vinegar, or some sour milk if you’re not concerned about keeping your starter vegan, stir it up until it’s the consistency of slightly thick pancake batter and wait. Just like with beer yeasts, the more oxygen you can pump into the batter when you stir it up, the faster the yeast will reproduce. Leave it out on your kitchen counter, loosely covered with a towel or with the lid ajar. I sometimes set it on the window sill.
You should see indicators of fermentation after you’ve left it out for a night or two on your counter, but it may take a few days to get as sour as most people like. The most apparent indicator of yeast growth is bubbles n the surface of the batter. Once you’ve seen the kind of action you’d like, feel free to take a taste of your batter to determine how sour it has become. Once the bubbles subside, the yeast has fully colonized the starter, and hopefully your lactobacillus will start doing its job thereafter.
After a while, you might also notice that the liquid separates from the flour a bit, leaving a tangy, yellowish layer. This is actually mildly alcoholic, and legend has it that Alaskan Gold Rush prospectors — themselves referred to as sourdoughs — would drink this for a little buzz. You’ll want to mix this back up into a homogenous batter when you get ready to bake with your starter.
Or you can purchase one, or there’s even a site that will give you some.
How do I bake with it?
Baking with sourdough starter instead of commercial yeast is a bit of a different animal. Just like working with beer, it requires patience — though we’re talking days instead of weeks in this case. Rises take longer, and gluten can break down due to the acidity of the starter. Most of the trials and tirbulations of working with sourdoughs are worth the result, and they can be mitigated pretty easily. Commercial gluten additives aren’t terribly expensive, and you can reduce that acidity by adding more flour and water to the starter before you use some to bake with.
Being that this isn’t really a baking blog, I won’t go into too much depth about the specifics, but essentially, you’re replacing commercial yeast with your starter. Just remember that once you’ve separated off the amount of starter you’ll be using in your baking project, you’ll need to rebuild the original starter with more flour and water, and you’ll also need to let the separated part come up to full yeast population in what’s called a “sponge” before you actually start kneading in the full amount of flour and proofing; sometimes this is called a preferment. Basically, to make a sponge you’ll add some water, flour and sugar to the starter and let that ferment. Overnight is usually fine.
Once you know the starter is activated, you can add the bulk of the flour and any other ingredients and bake essentially the same way you would with commercial yeast. The big difference is that it may take a bit longer to rise. The actual baking is exactly the same.
The Wikipedia entry on sourdough is also a good resource for links to articles about how to bake with a starter.
But what about the beer?
This starter would be enough to innoculate a fermenter of beer, though I wouldn’t necessarily recommend just dumping some flour into a well-formulated wort. My suggestion is to consider using a part of your sourdough starter to make a brewing yeast starter.
But first note that it is sometimes VERY difficult to sanitize your equipment once you’ve purposely infected it with wild yeasts and bacteria. I VIGOROUSLY recommend using equipment that is purchased specifically for your sourdough project unless it’s glass equipment. Plastic parts in particular are notoriously difficult to ensure of proper and complete sanitation. This means that your racking cane, associated tubing, bungs, caps, and airlocks should all be specific to this and other wild yeast projects. You also might want to keep everything associated with it away from your normal brewing equipment, as sometimes airborne cross-contamination can occur.
With that caveat in mind, pitch a bit of your sourdough starter into some dissolved and boiled then cooled, unhopped malt extract, and wait for it to take off. Wheat beers are good choices for wild yeast projects both because they’re relatively cheap and because they really allow the flavors produced by the yeasts to stand out — think Lambic! At the same time, don’t be surprised if it sucks. We don’t all have the luxury of living with Belgium’s unique symbiotic flora like Brettanymyces Bruxellensis, but sometimes you get lucky. Remember, this is an experiment; it’s probably best not to pitch this into a barleywine and then be stuck with a $75 keg full of undrinkably sour beer.
If you try this out, please let me know how it works for you.
Tags: bread, Brewing, Fermentation, sourdough, wild beer, Yeast