Under the usually followed guidelines for sourdough starter feeding, if one has 200 grams of sourdough starter (100 grams fermented flour + 100 grams water), they need to feed 100 grams of flour and 100 grams of water to the starter for 12 hours, and when they therefore have 400 grams of sourdough starter (200 grams of fermented flour + 200 grams of water) by the end of 12 hours, they will need to feed the starter 200 grams of water and 200 grams of flour, thus getting 800 grams of starter by the end of 24 hours, comprising 400 grams of fermented flour and 400 grams of water.

This means, in total, they would have obtained 300 grams of fermented flour and 300 grams of water extra, on top of the already existing sourdough starter.

However, I wanted to skip the 12 hour feeding and wanted to directly feed 300 grams of flour and 300 grams of water and let it ferment for 24 hours. Would this result in overfeeding and eventual dilution of the sourdough culture in the starter? Or would this result in underfeeding and eventual weakening of the sourdough culture due to lack of sufficient food for the bacteria and the yeast? Or would this be just the right amount of feeding and be thus stable?

I can, at most, do a mixing of the starter dough at the 12 hours mark with a spoon so that it starts off a sort of "proofing" fermentation after the "bulk fermentation" that happened for the first 12 hours.

Note: I plan to do this daily, hence any deviations in the concentration/strength of the fermenting bacteria/yeast will likely magnify exponentially as the days go by.

1 Answer 1


If I am understanding your post, you are missing the part of the process during feeding when you discard a portion of the starter. This discard is necessary in order to keep the acidity under control.

Next, your feeding regimen depends on whether you are gearing up to use the starter in a bake, or if you are just maintaining your starter.

The ratio of water and flour for feeding is important, but the amount doesn't matter that much. I maintain less than 100 grams. When I get ready to bake I discard a little less than half, and feed with 30 - 40 grams flour and the same amount of water. I do this every 12 hours or so for a couple of days, until I get strong activity. The night before the bake I increase the flour and water so that I have the amount of starter necessary for my formula.

12 hours is about the amount of time (depending on temperature) for the existing starter to "consume" the new flour addition, regardless of amount.

So, if you are just maintaining, feeding every 24 hours is fine. Mine is in the refrigerator and hasn't been fed for a couple of weeks (thanks for reminding me).

If you are gearing up to bake, you want to use your starter at peak activity. So, feed at least every 12 hours, but you have to look at it to tell when it is at peak activity. Local conditions impact this.

  • "If I am understanding your post, you are missing the part of the process during feeding when you discard a portion of the starter. This discard is necessary in order to keep the acidity under control." Can you elaborate on this a bit more? I thought that, theoretically, if you had an infinite amount of water and flour, you could start with 2 grams of sourdough starter-1 gram sourdough fermented flour and 1 gram water and keep doubling it every 12 hours, I'd get exponentially increasing sourdough starter with no issues? Jul 6, 2023 at 8:17
  • You can use any amount you like. The ratio is what is important. However, as your starter grows, so does the level of acidity. That is not a problem if you remove a large portion to bake with as soon as it is at peak activity. If you are feeding for multiple cycles without using, you need to discard a portion of the starter to control the acidity. Too much acidity will impact future yeast and bacteria activity and the the rise of your bread.
    – moscafj
    Jul 6, 2023 at 11:04
  • I'm still having trouble understanding how the acidity is reduced by removing some of the starter-after all, once you remove a bit of the starter, you just have less of the same thing. If I had 100 mL of 30% hydrochloric acid (with pH, say, -1), and I were to remove 50 mL of that solution, I still have 50 mL of the same thing and its pH still remains -1. Am I mistaken somewhere? Jul 6, 2023 at 12:55
  • Remove when feeding, so you are diluting the acidity that is produced during activity, by adding more flour and water.
    – moscafj
    Jul 6, 2023 at 14:35
  • but couldn't you do the same thing by just adding even more flour and water to the original starter without removing any starter? Say, each of us has 200 grams of starter. You remove 100 grams from your starter, and add 50 grams flour and 50 grams water. And I don't remove anything from my starter but add 100 grams flour and 100 grams water. The ratio of new flour to old fermented flour in the sourdough is exactly the same for both of us. Are you saying you and I will obtain sourdough starters, after fermentation, with different levels of acidity even though all the ratios are the same? Jul 6, 2023 at 15:01

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