Most of the yeast we use for baking, brewing or nutrition consists of the same organism: Saccharomyces cerevisiae. Humans have been enjoying the bubbly benefits of yeast for thousands of years, but it wasn’t until the 19th century that we began to better understand it, and thus produce it on a larger scale.
A few customers have come to us in search of cake yeast, but fresh yeast’s incredibly short shelf-life limit it to commercial use. Home bakers are advised to substitute 2 1/4 teaspoons of dry active yeast for one cake (.06 ounces) of fresh yeast.
Dry active yeast is cake yeast that has been dried to give it a longer shelf life; think of it as yeast in hibernation, just waiting for a warm bath to wake up.
Instant yeast is faster acting than dry active yeast, and doesn’t require rehydrating. Bread machine recipes often call for this sort of yeast.
Brewer’s yeast can refer to two things: the live yeast used to make beer, or the by-product of brewing which is no longer alive. The by-product, which has a strong umami flavour, is high in B-vitamins and chromium.
Nutritional yeast, like brewer’s yeast, is deactivated yeast that’s high in B vitamins. It has a nutty, cheesy flavour that’s not quite as strong as that of brewer’s yeast, and it comes flaked or powdered.