How to Make and Keep a Sourdough Starter#

There are several variations on this theme. A quick search on the web will turn up dozens of methods for making a sourdough starter, not all of them totally successful.

What we've written here is simply What Worked for Us. YMMV.

There are really 2 different HowTos here. The first deals with Getting Started, whilst the second part is Care and Feeding of Your Sourdough Starter. In truth this is backwards! Care and Feeding is what you will do on a week-in and week-out basis once you have a starter well-established, whilst Getting Started only really happens once. Or perhaps you're more adventurous than we and you keep a whole Yeast Library with different yeast strains suited to various styles of bread. Go, you!

Starting a Starter#

To make your very own Sourdough Starter, just bake a loaf of white, brown or rye bread, using whatever yeast the recipe recommends. Wholewheat bread will do, too, but you'll end up with a lot of chaffy bits in the starter. It's not a problem, and the starter will soon clear in a couple of generations. Note that commercially-produced wholewheat flour is but a pale and pathetic imitation of the Real Thing, having been torn apart, bleached, "fortified", purified and then put back together in some way that maximises the mill's profits.

If you're in the lucky position of being able to buy a "sourdough yeast", then by all means do that. You'll probably have a bit of a head-start on its further development. Otherwise just use whatever yeast you find in your local supermarket. Instant, dry or liquid; any will do. Beer yeast will do in a pinch.

Make a little more dough than the recipe calls for - perhaps an extra cup of flour - or just accept that your bread is going to be a little smaller than usual. When you've finished kneading the dough, break off a lump of dough the size of your fist or a bit bigger, and place it in a bowl. Cover with a cloth, and leave this in a warm (not hot!) place for three or four days. Bake the remainder of the dough into a conventional bread.

After your lump-o-dough has sat around for some days acquiring wild yeasts from the air, add a couple of cups of white-bread flour and enough warm (body-temperature) water to make a stiff batter. This is your first starter. If you don't have white flour, that's OK, use any other flour; it's simply that white flour is slightly easier for your still-vulnerable and tender yeast colony to digest. If you're aiming for a yeast strain tailored to a particular style of bread - perhaps Rye or Corn bread - then certainly use the appropriate flour rather than white-bread flour. You want to actively select yeast cells that thrive in the circumstance you intend to put them to work.

You should also add a couple of tablespoons of sugar - brown sugar is better, simply because it tastes better. Or use molasses, glucose, honey or malt-extract instead of sugar. What you choose here will have an influence on the taste of your sourdough starter in the long term. Sugar or molasses is sucrose; malt extract is maltose; and honey is a complex mixture of stuff. What you use will influence which sorts of yeasties thrive in your starter, and which varieties of yeast are discriminated against. Some yeasts prefer maltose, some sucrose, and so on. This is the chief difference between Ale yeast and Bread yeast; they are otherwise exactly the same species of organism.

Bung this lot into the refrigerator until you're ready to bake your first sourdough loaf. You now have your first-generation sourdough starter.

Using, Maintaining and Developing Your Sourdough Starter#

When next you bake bread, start the day before you want to bake. Scoop your starter into a bowl, add two cups of flour and enough lukewarm water to make a sloppy batter. Allow it to sit in a warm place for several hours or overnight. There should be a fair number of small bubbles in the "batter", and it should smell nicely sweet and "yeasty". If it has a noxious, noticeably "off" smell you've been unlucky. Either the yeast you started with was not very healthy and robust to begin with, or you've plucked a particularly virulent and nasty wild yeast out of the atmosphere. Either way you'll want to discard the whole lot and start again. This eventuality is very unlikely, though, and you should have a bowl of healthy yeasty starter.

When you're ready to add the starter to your bread mixture, first scoop a cup or two of your starter batter into a bowl or other container with a lid. This lot you keep for next time, and the remainder of the starter you use to make your bread. Put the container in the fridge for your next baking day, but don't seal the lid - you want the yeast to be able to breathe. The lid is simply there to prevent nasty accidents in the fridge that result in other foods contaminating your sourdough starter.

And that's the cycle: Bulk up the starter with fresh flour and water; use most for baking bread, but keep some back for next time. That simple.

For the first several generations your starter probably won't taste very "sour". It takes time for the starter to acquire a distinctive yeast ecosystem. It also means that every sourdough starter is absolutely unique. Nobody will be able to imitate your breads! Very, very occasionally you may get unlucky and find the starter acquiring an "off" taste. Chuck it and start again. Mostly this won't happen though, because you've started with a very strong yeastie population from the commercial yeast in your first starter, and these yeastie beasties will outcompete any of the unpleasant wild beasties that may stray into the mix.

After four or five generations of starter you should have a fine, distinctively sour starter, and you'll never need to buy yeast again.

People who are exceptionally more organised than we might like to try keeping several strains of starter - one lot fed on (say) malt and rye flour, another lot fed on honey and wheaten flour, and so on. Please let us know how it turns out.

Keep in mind, too, that using a sourdough starter will require a change in your bread-making routine, since it will likely mean that your bread rises quite a bit more slowly than when using commercial yeasts. Especially "instant" yeasts. The commercial yeast producers add a number of yeast nutrients, anti-caking agents, and boosters to ensure the shelf-life of yeasts and a very high level of activity.

Remember and give thanks to the little yeastie beasties who leaven our bread and beer. Without them life would be much less palatable.