I have a nice bowl of sourdough starter sitting in my kitchen, and I love making my bread as sour as possible.

Right now I let my loaves rise for a little longer, but is there a way I can alter my starter's environment to select for a sourer mix of microorganisms ("selective breading" would probably be the appropriate phrase)?

  • You could leave out some of the starter for longer to get the appropriate level of sourness (split off from the fed batch), and then if more leavening is required near the end of the bread-making process add some commercial crack yeast to speed things up. Also try more water in the starter, as that might favor LAB over yeast.
    – thrig
    Aug 16, 2016 at 14:45
  • see also cooking.stackexchange.com/questions/64979/…
    – rumtscho
    Aug 22, 2016 at 8:27

3 Answers 3


Yes, but it might have other effects that make it less effective as a leaven.

When I was experimenting with sourdough in the past year or so after a long hiatus, I had a pretty good batch going and parked half in the fridge, then had some life events that caused the part that was out to be left 24 or more, not 12 hours between feedings, and it turned very, very sour - but it also didn't do much for raising the bread.

Unless you are fixated on getting there via sourdough, I'd suggest picking up some citric acid if you like your bread "as sour as possible" - though even that might do in your yeast if you use too much - of course, there's always really sour flatbread, I suppose, by either method.

  • Thanks! After doing a bit more research, I also found this article gave me some additional guidance. But adding some citric acid seems very feasible, especially considering any starter will end up drifting back to the locally prevalent microorganisms.
    – Kupyn
    Aug 15, 2016 at 3:34
  • Or yogurt. Home made stuff gets pretty sour, and lactobacillus in bread type things add flavour. Aug 15, 2016 at 5:10

Given that you are working with a combination of bacteria and yeasts in a "wild yeast" culture, it's going to be very difficult to specifically engineer that. Indeed, the tendency is that, eventually, whatever wild yeast combination is native to your area eventually infiltrates or even takes over most cultures.

If your just looking for a little bit more "sour" you could try "sour salt," which is pure citric acid. Some view that as cheating, but as an enhancement to a natural sourdough culture, as opposed to trying to fabricate it, entirely, it comes out not tasting forced.

  • When I set out on my quest to find citric acid at a reasonable price in reasonable quantities (100 lbs was pretty cheap per pound, but far too much for casual use) I learned of the sour salt name and looked for that. Have never yet found it. Eventually found citric acid (sold as citric acid) in the mostly Indian spice aisle at the Asian food market. This will vary by locale, presumably.
    – Ecnerwal
    Aug 15, 2016 at 17:37
  • I've found it in the canning ingredients and materials section of the grocery store (you can use it as a prep for drying or canning foods to keep the foods from oxydizing/browning). I think they sold it in a plastic jar, kind of like the ones they use for store brand garlic or chili powder. Not cheap, but since you use fractions of a teaspoon per loaf, it goes a long way. Here's a baking supply company - King Arthur's (I highly recommend their live sourdough starter culture as well - very sour, very strong raising action): kingarthurflour.com/shop/items/citric-acid-sour-salt Aug 15, 2016 at 17:43
  • You can often find soursalt in kosher markets. It is used in s lot of kosher recipes
    – user49943
    Aug 22, 2016 at 3:14
  • The idea that "native" wild yeast combinations would take over is wrong. The environment in your starter jar is the single most important factor for establishing a culture. Even if the yeasts were so different in different parts of the world, you couldn't breed yours at an arbitrary combination of pH, temperature, etc. In reality, the theory of "local strains" has been disproved as myth, the large differences in starters are due to different starter methods plus local temperature.
    – rumtscho
    Aug 22, 2016 at 8:25
  • Nonsense. Unless your kitchen is sealed like a biolab at safety level 4, when you open your starter to use it, when you feed your starter, any organisms in the air are going to mix in. It make take a very long time, and it may not entirely take over, but it is going to eventually change your starter. The idea that the combination of flour and water in a jar would magically favor one combination of yeast and bacteria significantly over another one is kind of silly. How do local strains even exist, under that scenario? If it has been proven a myth, please link to sources. Aug 22, 2016 at 13:30

From what I read in Flour Water Salt Yeast, if you let your starter ferment at lower temperatures it should encourage the production of acetic acid, which is more "sour" than lactic acid normally produced by your lactobacilli.

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