The Fresh Loaf

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Sourdough + Yeast?

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sandy2's picture
sandy2

Sourdough + Yeast?

I encounter some sourdough bread recipes that include commercial yeast as well as starter.  I read somewhere that this isn't advisable, as the little beasties try to kill each other.  Could this possibly be true?

suave's picture
suave

Whatever they might be trying to do to each other does not happen on 2-3-4 scale that it takes to raise the dough.  Besides, the experiments like that are typically done in pure sourdough cultures, not in very diluted medium like a dough.  Bottom line is, those recipes are perfectly fine.

aroma's picture
aroma

... I add the yeast to the final mix after the sourdough sponge has had an overnight fermentation.  I have found that with the flours available to me, I need a small boost to get the oven spring I like.

sandydog's picture
sandydog

Many commercial bakers add yeast to sourdough breads at the mixing stage - It brings the bread to the oven a little earlier, thereby making for a shorter working day (And, I guess, less wages to pay?)

If you keep the % of added yeast low many people would be hard pressed to tell any difference in flavour, as the sourdough culture has already built in the desired characteristics to your dough. 

Why not try doing it both ways - Ferment a batch of sourdough, split it in two, add (Say 0.2% dry, or 0.5% natural)) yeast to one half, then mix and continue as normal with both doughs - Tell us what you think when you taste both loaves, noting how each tastes. Then we will all know what difference (If any) there is.

Happy baking,

Brian 

David Esq.'s picture
David Esq.

Some of the most popular bread books inude such recipes. The authors suggest it can make the bread less dense and, of course, can reduce the proofing time while giving the benefits of sourdough. 

PetraR's picture
PetraR

I read that a small amount of yeast can be added, I do not see that it would do any harme so I never tried, I think I am a bit of a purist when it comes to my SD bread:)

Toad.de.b's picture
Toad.de.b

I won't add to the solid practical suggestions above.  But let's be clear here:  The 'warnings' you may be remembering surely intended to convey that the more microbial diversity you introduce into your dough, the more competition among them that will result.  And since commercial yeast have been selected for their vigor (including competitiveness for resources), they can dominate if not handled correctly, which usually means giving your naturally weaker SD microbial population a good long head start -- adding but a small amount commercial yeast to the final dough.

That said, yes, microbes do "try to kill one each other" (ignoring the anthropomorphism of "try").  Microbial competition drove the evolution of antibiotic production.  But I would guess it's more competition for resources (carbon and nitrogen compounds) that characterizes their key interactions in our doughs.  Starving, not poisoning, their adversaries.

Tom

sandy2's picture
sandy2

Thanks for all of the answers!

mixinator's picture
mixinator

Adding baker's yeast can definitely have a profound effect on the flavor of sourdough.

sandy2's picture
sandy2

In your opinion, for better or for worse?

mixinator's picture
mixinator

In my opinion, for the worse. It robs sourdough of its distinctive tanginess. If someone doesn't like the tanginess, it might be for them.

emkay's picture
emkay

Jeffrey Hamelman mentions in his book, "Bread", that up to 0.2% commercial yeast can be added to a levain dough without any noticeable changes in the bread's sourdough characteristics.  On a couple occasions I've added 0.1% instant dry yeast to my levain doughs and I haven't noticed any changes in my bread's texture or flavor. My bread was still quite tangy. The only thing I noticed was I needed a slightly shorter fermentation.  I've also tried adding 0.5% yeast and noticed a difference (for the worse). So the effect totally depends on how much yeast is added to the levain dough.

Mini Oven's picture
Mini Oven

how much yeast is added to the levain dough."    

... when it is added   ...and how much wild yeast and bacteria are already active in the levain.

I've had sourdough cultures heavy with bacteria  (tipped out of balance) that tasted great but barely rose resulting in tasty bricks.  Letting them ferment long enough for any natural yeast to multiply and raise the dough usually resulted in dough degradation.  Adding enough instant yeast to raise the loaf before it degrades can often save a loaf from becoming a brick.  Tricky because adding yeast also speeds up fermentation and thus degradation but also adding its own flavour.   

I see it this way...  Produce the desired flavour before the dough falls apart.   Yeast is a tool.  Using or not using purchased yeast does not make one a purist.   I could argue that using instant yeast has already been done for generations so that it's use has become traditional.  I agree that flavour profiles can change with the variety and numbers of yeast and bacteria used.  

If you can get wild yeast to make the desired flavour, and use another to kill the first group by stealing their food and raise the loaf, then I say, more power and understanding to you!  We bake and kill them all in the end.  Handy little tools!

emkay's picture
emkay

Hi Mini,  You said it better than I ever could have said it if I even knew enough about the wee beasties to say it at all!  :)

I guess I should have qualified my statement with "all things being equal" the effect depends on how much yeast is added to the levain dough.  So in my case it would be the same baking session with the same levain and same batch of dough. One half with yeast and levain and the other half with levain only (added to the dough at the same time).  Or one half with 0.1% and one half with 0.5%.

Mini Oven's picture
Mini Oven

I was just adding to it.  I like your post.  You said it very well and you are right.  I should have added, I couldn't agree more!

Most of us can't see those little creatures, we have to rely on our other senses.  I wish I new more.  I'm glad they can't scream.  Curious to see if you try 0.2%.  

I tend to use the method of adding yeast to speed up a long ferment with little or no gas formation.  Then it is a power shot of 1.5 or 2% in a paste to get that dough thru a final rise quickly (maybe with one soft fold.)  After your observations,  I would be tempted to try the 0.2% yeast the next time when mixing up the same dough and get ahead of the frantic waiting beyond predictions.  

Although...  waiting gives me time to prod, sniff and poke my dough.  Never get tired of doing that...  :)

 

emkay's picture
emkay

Hi Mini, I knew that you weren't being critical, but your post made me realize that I should probably clarify or expand on what I wrote in my original comment.  I hope to do an experiment adding varying amounts of instant dry yeast to a batch of levain dough just for the sake of my scientific curiosity. Once a scientist, always a scientist.

:) Mary

sandy2's picture
sandy2

Cool!  Please report back...I might have to do the same. 

mixinator's picture
mixinator

Letting them ferment long enough for any natural yeast to multiply and raise the dough usually resulted in dough degradation.

This isn't a problem for skilled, experienced sourdough bakers.

I could argue that using instant yeast has already been done for generations so that it's use has become traditional.

Traditional, no. Common, yes. It's how big bakeries make sourdough these days. They can turn out more loaves per day at lower cost.

A few bakeries still do it the old-fashioned way.

mixinator's picture
mixinator

Jeffrey Hamelman mentions in his book, "Bread", that up to 0.2% commercial yeast can be added to a levain dough without any noticeable changes in the bread's sourdough characteristics.

One gram in 500 g of flour.

The only thing I noticed was I needed a slightly shorter fermentation.

This makes a difference in a big bread factory where time is money. Is the home baker really in that much of a hurry?