After weeks of sluggish dough and frustratingly long days in the bakery I finally realized the problem wasn't the cooling temperatures but my sourdough culture itself. At some point I must have let it get too hot or too cold or too acidic and the community of yeast and bacteria became unbalanced. I pulled my backup sourdough culture out of the fridge and added it to the mix, and voilà, this batch of bread rose beautifully and on schedule.
If you bake your own sourdough bread, keep a little backup sourdough! You can start a new culture from flour and water in a week or two, but why wait if you don't have to? Cold and low water availability are two very good ways to slow down fermentation. I use both, taking a spoonful of ripe sourdough and mixing it with flour until its the texture of dry crumbs, then storing those crumbs in a jar in the fridge. Every 2-12 months (whenever I remember) I refresh the jar. But you can also keep a jar of wet sourdough in the fridge, protected by the a layer of alcoholic "hooch" that forms on top, or a ball of stiff sourdough buried in flour, or dried sourdough flakes at room temperature. There's no wrong way, as long as it works.
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