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Contradictory Logic in Feeding and Preferment Percentages

applesaredarkerthanithought's picture

Contradictory Logic in Feeding and Preferment Percentages

I have been making a slight variation of the "Whole Wheat Hearth Bread" without commercial yeast from Reinhart's "Whole Grain Breads" and I want to gently reduce the sour tang that appears after continuous chewing.

It is made by preparing a non-fermenting soaker and a sourdough starter on day 1. The starter is left to double in size and then refrigerated. On day two the soaker and the starter are mixed in an almost 1:1 ratio, let to double once again before proofing and baking., proof and bake.

Because of the 1:1 ratio, the fermentation time on day 2 is relatively quick (about 3 hours at 21C where I live), but on day 1 the starter can take upwards of 7 hours to double because there is only a percentage of about 33.3% 'mother-starter' used to make the 'preferment-starter'.

I have read many times here and in books that due to bacteria acting slower than yeast in fermentation, more mother-starter and less time will be less sour than using less mother-starter and more time. I decided I would try adding more mother and ferment quicker because with the overnight fridge fermentation, the enzymes should still have time to release plenty of sugars and develop flavor, while in theory it would produce a slightly less sour dough.

Shortly after, I realized something strange. As well in my reading of books and the forums here, I learned that to make your mother-starter less acidic you should be feeding with more flour/water and for a more acidic mother-starter to feed with less flour/water. Isn't this way of thinking the exact opposite advice when it comes to bulk fermentation as stated in the paragraph above?

Thanks so much for your help guys. This really is an awesome community!

tpassin's picture

I can't answer your question, but your framing has left out one factor: more bacteria does not automatically mean more sour taste, nor does being more "acidic".  If you develop a lot more acetic acid, then yes, but if it's lactic acid, then no.

Abe's picture

And I don't think one can point to one factor that will make a starter/bread more or less sour. 

It's not just the amount it's fed. There's temperature, how long it is left to ferment, flour used etc. 

I think the best way, without getting too scientific about it, is to try different recipes and methods then settling on a method you like best. 

Keep on experimenting. 

P.s. I find it easier to not be too fussed about the starter. It just where you store the yeasts and bacteria. The balancing act begins with a levain build where you start to home in on the results you want. 

SueVT's picture

When retarding sourdough, the cold temperatures will favor those organisms (bacteria) that produce a sharper or more acidic taste. But, you can make a 1:3:3 poolish, leave it on the counter overnight and bake with it the next day without producing too much sourness, if that matters to you. My experience these days is mostly with lievito madre, which is kept at a lower hydration and given both a warm and a cool feeding each day to control the balance of organisms/flavor.

mariana's picture


The simplest practical solution to you sour bread taste problem is to add a tiny bit of soda to your bread dough. It will neutralize the excess of acid. How much will you need depends on your taste preferences, maybe 1/4 tsp orveven 1/8 tsp would be enough.

Acidity comes in two forms so to speak, strongly/sharply tasting strong acids and aromatic but weakly/mildly tasting weak acids. Together, they contribute to the total acidity known as TTA which defines bread flavor.

When you refrigerate your bread dough or starter, the bacteria shift to producing more strong acids and less weak acids. So, one way to reduce acidic taste is to not refrigerate them and to ferment them at warm room temperatures. Then your bread will be less acidic to taste, not as sharply or unpleasantly acidic.

The rest of the discussion in your text is more or less about comparing apples to oranges. Starters and bread doughs are different animals, as different as ingredients and finished products made with or from those ingredients.

A starter is just an ingredient, it has certain quality requirements ( target values of pH, TTA, and gassing power that reflect its quality or maturity/readiness), but its main purpose is to propagate microorganisms, make them multiply, so there is a certain number of them in a cup of starter. Later, when you measure your ingredients, including starter, you measure with the starter a certain number of grams of yeast and bacteria inside it needed to leaven and to sour your bread dough on schedule.

A starter is never made to be too sour or less sour on purpose, because nobody will eat it or bake it into a loaf and because too sour or not sour enough starter is a low quality starter, it does not have enough microorganisms in it or microorganisms in their optimal state to bake with it.

A batch of the bread dough (or preferment/levain) is different. Its purpose is not to propagate microbes inside it but to make a tasty loaf of bread, so it is handled with that goal in mind.

more mother-starter and less time will be less sour than using less mother-starter and more time.

Essentially, the more microorganisms you introduce to your bread dough with your starter, the less they will attempt to reproduce. For that reason, commercial yeast's cells never multiply inside bread doughs or preferments, there are too many of them added (and conditions are far from optimal for them to grow in numbers)!

If you introduce fewer cells of yeast and bacteria and give them a lot of time, they will not only sour and leaven your bread dough for a long time, they will also multiply in it and thus sour it even more.

to make your mother-starter less acidic you should be feeding with more flour/water and for a more acidic mother-starter to feed with less flour/water

Time plays a role here and the abundance of sugars. If you add fewer cells of microbes to a lot of flour, they will not make your starter sour (ready, mature, having target pH and TTA) on schedule. The abundance of sugars in a lot of flour added to a little starter will stimulate yeasts and they will make your starter rise tall quickly making you believe that it is ready for use when the acidity is nowhere near the target values. 

When a starter is fed a little flour, bacteria will eat all that sugar and only some leftovers will be left to yeasts to consume. That is the meaning of symbiosis, a stable community of yeasts and bacteria in a starter, where proportions of yeast and bacterial cells are 1:100. If you feed your starter a lot of flour, the free sugar makes your starter more yeasty, the proportion shifts to 50:50 and less acid is produced.


jkandell's picture

The easiest way to get rid of the sour aftertaste is to convert the recipe to commercial yeast. You can still ferment the dough for flavor but it won’t  have the hint of sourness that is always there with natural yeast.