Baker’s yeast explained: know your ingredients

By / Food / July 4th, 2020 / 19
baking and yeast explained

Social Media feeds are newly brimming with images of homemade focaccia, bagels and sourdough, while yeast shelves in grocery stores look a little lonely these days. Whether you are observing the home-baking trend from a distance or your latest loaf is already in the oven, you might be wondering what yeast actually is, how it works and why there are so many varieties.

Yeast, like mushrooms and mold, are a part of the fungi kingdom. They are single-celled microorganisms that work by feeding on sugars, which they convert to carbon dioxide and eventually alcohol. The trapped CO2 is what makes your beer bubbly and your bread rise.

There are hundreds of species of yeast, however the kind you are seeing in commercial grocery stores is probably baker’s yeast. There are two main types of dry baker’s yeast: Active dry yeast and Instant yeast.

Active dry yeast

These often come in flat packs (sometimes of three), where the large granules are partially dehydrated and there are live cells surrounded by dead ones. Active dry yeast is typically activated in warm water or milk before mixing with other ingredients in a recipe. This also ensures its activity and that your packet is neither expired nor defective. If your yeast is active, it should start to foam when activated; if not, check the expiry date or try a fresh packet.

Instant yeast

Instant yeast has smaller granules and is made up solely of living yeast cells. That means it can be mixed directly into a recipe without activation. If you would prefer to use instant yeast and a recipe calls for active dry yeast, you can make the substitution by adjusting the ratio. For every teaspoon of active dry yeast, use instead 3/4 teaspoon of instant yeast. So, if a recipe calls for 2 teaspoons of dry yeast, you can use 1 1/2 teaspoons of instant yeast.

Will nutritional yeast work?

Unfortunately, no. While it might taste great as a seasoning on popcorn and other snacks, nutritional yeast undergoes a deactivation process where the live cultures are killed by heat. That means it is rendered unable to trap carbon dioxide and will not make your bread rise.

Baking from home can be really rewarding. You get to tailor recipes to your own specifications and preferences, but it can also be frustrating if you don’t know what you’re working with. Yeast is complicated, and these two types of baker’s yeast barely scratch the surface of what exists, but hopefully it gives a little insight into what gives your bread that airy deliciousness and is fueling the quarantine trend.


Natalie Pressman is a freelance journalist based out of Toronto. She enjoys arguing loudly about oxford comas, and almost always has snacks. You can find her on twitter at @natpressman.

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