Last time I tried to raise a baby sourdough starter, I detailed its progress in these pages, so that everyone was able to see it stagger towards an untimely, fart-smelly death. This time, I've kept quiet, but I'm glad to announce, now they're both weaned, that I have raised two healthy starters: one rye and one wholewheat.
Both were surprisingly easy. I did the rye one first, mixing equal weights of flour and water, and feeding daily for a week. I used an old piccalilli jar, and the big difference with last time was that I kept the lid on. Obviously this kept away the fruit flies that flocked around my earlier attempt, but also I found that initially the starter had a pickly smell, despite how carefully I had cleaned the jar and lid. By the end of the week this was overwhelmed by the boozy smell of yeast. I then moved the rye starter into another jar, and started a wholewheat starter in the piccalilli jar. Again, an initial pickly smell gave way to a proper yeast scent. I have no idea if the traces of pickle helped, but it's quite possible!
So, I have two kinds of starter. They're both now living happily in the fridge, getting fed once or twice a week. The rye starter looks and smells better, if I'm honest, but both are quite young (about a month) and will I'm sure mature.
Using them, though, is quite different from using commercial yeast, and I'm still learning.
(1) As expected, the sourdough yeast is weaker and slower, so dough needs a longer rise. On the other hand, it seems that during rising the bacteria in the starter, which are quite acid, break down the structure of the dough, so that it becomes wetter, and can look a bit uncooked in the centre after baking. It's a similar effect to using too much Diax - diastatic malt powder - which I've stopped using at all.
(2) so this means you can't - as with commercial yeast - subsitute time for temperature. I think the acid action works at any temperature, so if you leave a dough in the fridge overnight, the destructive acid has its fun all night long while the yeast is more or less sleeping. The dough rises, but then has no structure for baking.
(3) and if you try to add more sourdough, to get more yeast into the dough, you risk making the final loaf unpleasantly sour.
(4) So, you need to rise the dough at a decent temperature, to reduce the time
(5) and you need to use less sourdough starter than some recipes suggest. I'm using about 2 tablespoons for 400g of flour
(6) and it may well be a good idea to mix the starter into the liquid, to ensure that it's evenly distributed among the flour
(7) and adding a teaspoon or two of sugar to the liquid will help the starter on its way, and give a colour to the crust that might otherwise be lacking.
(8) It's important not to overprove the dough. Don't expect a similar rise to what commercial yeast will give. A 50% rise is the best you can expect.
These are some of the lessons I've learned so far. Generally, it's clear that sourdough baking is a more skilled endeavour than baking with commercial yeast, and I'm not there yet. But at the best, the results have been encouraging, and as the starters and I develop our powers, the bread will get better. So that one day, I may even post a photo of a finished loaf.