For many years I had a commercial baker’s approach to sourdough wheat: the proportion of common leaven in the daily feed was high, at 40%. The advantage of this was that on a commercial baking day if the production leaven was made at a suitable temperature it would ripen in two hours, meaning that the whole operation from leaven feed to bread could be done in one work shift. Kept at ambient temperature, not refrigerated, the leaven was always finished as a stiff dough at its daily feeding. By the next day that stiff dough has become damp, rendered moist and sticky by the natural process of fermentation as the yeast destroy their surroundings.
Definitions: (i) “common” leaven refers to the stored leaven that is routinely fed;
(ii) “production” leaven (PL) refers to a body of refreshed leaven that is set up to make a specific amount of dough that is needed for production purposes, being the last feed before bread-making
(iii) for the formulae: L is Leaven; W is Water; F is Flour
When I am teaching, commercial baking methods can be inappropriate for a group of home or hobby bakers, who do not need to make vast quantities, and their leaven is more likely to live in the ‘fridge and be brought out to enjoy ambient temperature as part of the process of being readied for a baking day. Now I wish to tell you about my new system which favours using less common storage leaven and a very slow production leaven, and is thus more in step with the practices of the home baker. For me, the good news is that my new procedure results in a more open textured sourdough loaf, featuring larger and more randomly situated bubbles in the crumb, with a dark and appealing crust colour. It also has excellent flavour that is not too sour, and will keep better too. The slow production leaven has been the contributor to all these positive changes.
The routine feed (usually daily) chugs along with this formula:
L = W; F = 2 x L (here leaven comprises 25% of the bulk), forming a stiff dough, and after the feed the unwanted surplus leaven is habitually thrown away.
Approximately 12 hours before the bread is to be made, the production leaven is prepared, using only a tiny amount of the common leaven , with a different formula, as follows:
L = 5% of total Production L [perhaps only 2% when warm conditions ]
F = 60%-65% of total PL
W = 37-40% of total PL [these percentages in F and W have a range that acknowledges different water absorption levels of available flours. e.g, using stoneground darker flour would be more like 60:40 flour to water; roller milled white flour may require 63:37 ]
If conditions are very cold, or you want it to be ready earlier than the 12-hour maturing period, then you could raise the common leaven to 10% of the total of the production leaven. Common sense must prevail, and soon practice and experience will lead you to the appropriate amount of leaven to be applied to your PL, and whether you get suitable ripening by keeping it firm or soft (slack).
[N.B.These figures are for the home baker. The commercial baker, using larger quantities will be wise to use only 1% to 2% of leaven if the slow production leaven is set for approx 12 hours].
Assume you want to have 2 large sourdough wheat loaves made, with the PL sitting overnight for about 12 hours, doing its slow maturing while your yeast colony reproduces and grows.
The amount of mature production leaven needed will be 500gm, made up with 25 gm of common leaven; 325 gm flour; 175 ml water = 525 gm.
The dough-making formula I have always used is this:
L = W, F = 1½ x L; salt is 1% of total
Apply the PL to the dough-making formula above, and these are the figures:
500 gm of production leaven [saved surplus leaven = 25 gm]
500 ml water
750 gm flour
salt is 1% of bulk = 17-18 gm
Good baking, Paul