A good friend from the ol’ hometown, Chef Tim, writes in to ask:
Are all commercial yeasts the same, meaning will they not only act the same but produce the same flavors? Is there anything on the market that bridges the gap between the simple convenience of commercially made yeast and the flavor-producing goodness of homemade (but unstable) starter?
The answer is that for all intents and purposes, commercial yeasts are the same. They’re made by the same processes, and are based on similar, though not necessarily identical, yeast cultures. Yeasts produce quite a bit of flavor on their own — compounds known as glutamates — though it’s the various compounds that lactic acid bacteria produce that are primarily associated with flavor in bread (and they’re not only the market in any product I’m aware of). These bacteria are present — though in tiny amounts — in packaged yeasts. Some brands of yeast may have a few more errant bacteria than others, but you’d be hard pressed to tell the difference, flavor-wise.
There are, however, ways to manipulate commercial yeast to bring out the maximum amount of flavor. For more on that see the post How to Fool Yeast