what I do know works most of the time, but like cheese, beer, wine and all the fermented things we so love, sometimes it just goes inexplicably wrong. having said that, I’ve got a method for use in a domestic kitchen that seems to work most of the time. (the problems associated with starters for domestic use include poor temperature and humidity control, not using the starter everyday, cross-contamination from other sources- like cheese mould).
if you bake bread everyday the Italian biga method is the easiest: keep a piece of dough out of your loaf, let it ferment overnight and add it to the next batch of dough (preferably don’t keep it more than a day or so). then keep aside another piece from the new dough and so on. I only bake bread once or twice a week so I find keeping a levain easier.
levain (takes 4 days)
for the initial fermentation:
make a small dough to start, using about ¼ cup of flour and a bit of water. leave it in a warmish place without a draught. it needs some air, so leave the lid of the container askew or cover it with a towel.
after 2 days it should have formed a crust. gently peel off the crust and discard. underneath it should be creamy and a bit bubbly, and smell sort of fruity or like beer. add double the previous quantity of flour, i.e. ½ a cup and mix to a dough with more water.
the next day peel the crust off again and add double the previous quantity of flour, i.e. 1 cup. mix to a dough with water again. In about 6 hours it should be ready to use. check that it is risen and a bit bubbly, and isn’t black (dead yeast) or bad-smelling (contaminated).
to make bread
take about half the starter and make it into a dough with additional flour, water, salt and oil. the guideline for ratio is that the starter should account for 1/3 to 1/6th of the total dough volume. being innumerate, I just put in about 1 tablespoon of starter to each 100g of flour.
this kind of dough takes much longer to prove than a commercially yeasted dough. about 12 to 15 hours should be sufficient, depending on weather and environment. longer proving time (not over proving) develops more flavour.
slow proving doughs can be hand shaped initially or at an early second proving, or in a banneton or brotform basket from the beginning.
the dough may form a crust. this isn’t bad but does somewhat affect texture and the way the dough will bake. if the room is very dry you can spray the loaf with water occasionally or humidify the area with trays of water.
to keep the starter alive
after you’ve made the dough the starter needs to be replenished. you can feed the starter soon after making the dough, but not too much. if it’s not too hot you can leave the starter on a shelf somewhere and feed it a little flour and water everyday, mixing the crust back in each time if it’s still soft enough, until you’ve built it up again. or you can feed it and put it in the fridge, taking it out the day before you want to use it, feeding it again and allowing it to ferment for a day.
some useful resources
bakers in Melbourne: Dench, Babka, Noisette (84 Bay St, Port Melbourne); (shame about Wildflour being closed for now)
somebody else's comprehensive list of all things sourdough
Carole Field's indispensible book The Italian Baker
some video interviews and demonstrations by sourdough bakers
