Alas, we do not live in San Fransisco. We live in Surbiton. So the sourdough bread we make will taste like Surbiton sourdough, not San Francisco sourdough. Sourdough is formed from the natural and wild yeasts and bacteria present in flour and in the air of the local environment. On reflection, I’m much happier that my bread tastes of Surbiton than San Fransisco.
There are good reasons to make sourdough. It restores our faith in the natural way of the world. Flour and water is all you need (and salt). It tastes good, it keeps well, it’s easy on the digestion and nutritionally beneficial. Harold McGee explains the science behind some of these characteristics in his book, On Food and Cooking, ‘…the bacteria somehow delay starch retrogradation and staling, and the acids they produce make the bread resistant to spoilage microbes; so the sourdough breads are especially flavourful and keep well.’
We also know that sourdough is easier to digest and that it has many health benefits, though McGee is silent on the science of these attributes. What he does state, is that sourdough is difficult. It makes sense to assume that though the process may be wonderfully natural, it can also be unpredictable and unstable. It’s all to do with the way the yeasts and bacteria develop and behave during leavening and baking. First, the bacterial will outnumber the yeasts and can diminish the yeast ability to produce gas. Secondly, the acid conditions and bacteria can weaken the gluten in the dough, making it dense. He recommends managing acid levels by keeping the starter less liquid, keeping it cool, aerating it and refreshing it often. Limiting the bacterial protein-digesting enzymes can be achieved by adding a full amounts of salt during the dough making process.
So, if we find that making our own sourdough is not as easy as some might have us believe, we can feel reassured by McGee that there is probably a good scientific reason to our travails. My advice, when it come to baking anything is that you need practice – only by baking something again and again can you get a feel for what is happening and have any chance to make an informed judgement to improve the bake. This reality is at its most evident when making bread. I don’t believe anybody will be fully aware and in control of what they are doing unless they have made at least 10-15 loaves. Until then, don’t even think of being critical of your results. You’re still learning…