Should I Put Commercial Yeast in My Sourdough?

A reader (“Q”) left a question on my How To Make Light Sourdough post. As her dough didn’t double in size, should she have added some fresh yeast?

My answer was so long it turned into this post.

I don’t advise boosting the sourdough starter with commercial yeast. That’s because I’m a sourdough snob. Commercial bakers sometimes add fresh yeast in order to schedule rising and baking times predictably, but for the home baker, the whole idea is to use the time-proven sourdough method to create a delicious loaf in her/his own kitchen.

My feeling is, if there’s commercial yeast, it’s not real sourdough. But like I said, I’m a snob. Who cares if it’s “real” or not except for yourself? For me, using sourdough is like having captured the soul of the wheat. But people eating the bread just want it to be satisfying and taste good.

There are several streams of thought. Some home bakers just want bread with that sourdough tang and don’t mind mixing yeasts. (I also make certain breads using “old leaven” or a “chef” – a small ball of dough from a previous baking that’s been left to mature and sour.) Some must cater to someone who’s allergic to fresh yeast but tolerates sourdough. Some seek the satisfaction of mastering a basic wild ingredient and getting great natural  flavor, texture, and digestibility. There is so much beautiful bread to make – my best advice is to go with what seems appetizing to you, master that technique, and go on to the next intriguing recipe.

But returning to “Q”‘s problem with a non-riser.

Was your starter recently refreshed and active? And did the sponge become light and spongey? If the answer is no to either question, there might not have been enough yeast to make the dough rise. An inactive starter might look impressive because there’s a lot of it, but it won’t do its job if most of the yeast cells in it are dead.

An alternative reason for a sad dough might might be insufficient flour to keep the yeast fermenting. If the dough was too sloppy to handle, you did the right thing in adding flour. If you’re outside of Israel, your flour will have a different quality than mine, and your recipe will need to be adjusted. In other words, from country to country, flours differ in ability to absorb water. There are other differences too, but that’s outside the scope of this post. Like every living thing, wild yeasts  need nutrients: the sugars in the flour, and oxygen. So with a very loose dough, you could either allow more time for it to rise – hard to say how long, but it could be several more hours – or sprinkle in more flour till you have a pliable, responsive dough.

Where was your dough rising – in a warm environment or a cool one? Too cold an environment will retard the fermentation of the dough, which can be desirable sometimes (allowing it to rise overnight in the fridge) – or not, if you’ve set a schedule.

It does take practice to create a good sourdough loaf. If you haven’t grown up watching Mom or Big Sis handle sourdough, you’ll need to acquire the feeling for the right temperatures, rising times, feel of the dough – by practice. Here’s a tip, though: the way you can tell if your dough will rise is by judging its feel under your hands. A good dough will feel tender yet firm, keeping its shape and even springing back a little under fingertip pressure, right from the beginning. A “loser” stretches out in broad ribbons and just flops back into the bowl; it feels heavy and dead.

If you’re unsure, add fresh yeast, I guess…but don’t put any into your sourdough starter, for it will “fight” with the natural yeasts and beneficial bacteria, spoiling it.

There’s so much sourdough wisdom out there it’s positively intimidating. But here, here, and here are a few of my favorite sourdough sites. Read through, choose your own way, and enjoy.