The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Commercial Yeast in your Sourdough?

Chode's picture

Commercial Yeast in your Sourdough?

In Ed Wood's Sourdough book, he writes to never mix commercial yeast into your sourdough starter or dough. I can understand the starter, but most of the books I've seen that address sourdough all call for a small amount of instant or active dry yeast.  This seems like a contradiction to me -- is Ed Wood just taking the position of a purist? 

It seems acceptable to use a small amount of commercial yeast in a sourdough bread recipe (1-2 grams) to boost the leavening power of the loaf. My understanding is that if you use too much yeast you'll loose the sour notes brought to bear by the sourdough starter itself.

Anyone want to weigh in on this?


janij's picture

You can spike the dough with commercial yeast to give you a shorter rise time.  But it will not be pure sourdough.  And yes it will not be as sour.

pattyfermenty's picture

I am curious as to how you are defining "pure" sourdough. I've often wondered what exactly is the difference between sourdough culture and "commercial" yeast anyway. If I create a poolish and put it in the fridge for 2 months, take it out and revive it, is it now a "culture".


Specifically, how would adding yeast, whether store bought, found, etc., prevent the dough from being sourdough. Or are you referring to the San Francisco bacteria specifically as that which makes "pure" sourdough?


Any comments appreciated.

proth5's picture

because I have been fooling around with hybrid levain/commercial yeast breads recently.

I find that even a small addition of commercial yeast really changes the character of the bread.  It does rise more quickly, but the crumb is compromised  (usually a bit more "spongey" and less open) and there is a significant lessening of the "levain tang."  On the plus side, oven spring is better.  On a good day my starter is pretty mild (which is what I want) so your results may vary.

I keep a very healthy starter and I find it raises bread just fine without adding commercial yeast and I prefer those results.

I consider that folks who are devoted to their sourdough might caution against using commercial yeast in breads, but I see that as a matter of taste.

Of course, as you pointed out, never put commercial yeast in the mother starter.

Your best option is to try various combination for yourself until you find the bread that suits your taste.

Hope this helps.  Happy Baking!

suave's picture

It is not all that uncommon, especially in large commercial bakeries where it is used to fine-tune rising times and to control acidity.  In addition there're some methods of elaborating starters, that develop acids at the expense of yeasts, so spiking the dough with yeast is required to get enough volume.  I think some books suggest using it to compensate for the quality of homemade starters which are often compromised by cold storage and irregular feedings.  I, personally, rarely use it in sourdoughs, there isn't any need with my starter, and I don't like extra oven spring it gives, but I wouldn't have any problem adding it.

As to adding yeast to starter - it will not harm it, it has been shown that commercial yeast doesn't survive there, but it's pretty pointless. 

Thomas Mc's picture
Thomas Mc

I think it's your bread, you can do whatever you want with it. It's a little arrogant of anyone to tell you otherwise.

I used to be a purist, refusing to add yeast to my sourdough, but right now my starter seems to make the bread a little too sour, so adding a little yeast to the dough shortens the rising time, lowering the acidity.

Have fun, experiment. Even if you fail, all it costs you is a little flour, water, salt and yeast. And the squirrels and birds love the failures.


lindasbread's picture

I don't use yeat in my sourdough. It would die if I add commercial yeast. My bread recipes are with and without commercial yeast. The one without take longer to ferment but have a better taste and are better for the digestive system.

Neil C's picture
Neil C

San Francisco Baking Institute's Suas recommends Instant yeast in his Liquid Levains and his'One Feeding SD formulas, but omits it in their San Francisco SD formula. 

Ref. Advanced Bread and Pastry pgs. 201-203

babmuna's picture

Technically, commercial yeast is not the same critter as wild yeast found in the air and on grains of wheat. The yeast they process and sell is saccharomyces cerevisiae, "brewer's yeast." Wild yeasts are a bunch of different guys, saccharomyces exiguus being the major one. Ed Wood and others just wish to retain that distinction.