Slow Food Baking 101: Understanding Sourdough, Commercial Yeast, and Home Yeast Cultures
Slow food baking has, for quite a while, focused on sourdough bread. Or various baked goods made from “sourdough discard,” whether they need leavening from yeast, or not. So much so, that sourdough bread has become something of a meme. But there are more types of yeast available to use than just the instant dry granules and sourdough cultures. Let’s go through the list and talk about what the ups and downs of each type are.
The choices include the familiar dry yeast – which comes in both “instant” and “active dry” varieties, commericial fresh or cake yeast, sourdough cultures, homemade yeast cultures, and brewers yeast.
Dry Commercial Yeast
Dry commercial yeast comes in granules. It’s usually sold either in packets – usually three to a strip, small jars, or larger vacuum-packed bricks. The packets contain 2 – 1/4 tsp of yeast. The shelf life of dry yeast is much longer than any other type. And you can extend it even further by storing it in an air tight container in the refrigerator or freezer.
Most dry yeast will be labeled either “instant” or “active dry.” “Active Dry” yeast should be combined with a little bit of milk or water and a tiny bit of sugar for 5-10 minutes to “bloom” before being added to the rest of the ingredients. “Instant” yeast can just be added with the rest of the dry ingredients without a need to bloom.
One more thing – Many companies also make a “gold” version that is meant for enriched doughs. High sugar environments are challenging for regular dry yeasts. Gold SAF and similar products have extra enzymes and nutrients that make the more suitable for doughs over 10% sugar. They’ll actually rise more slowly in low sugar doughs.
Cake or Fresh Yeast
The other major form of commercial yeast is fresh or “cake” yeast. This used to be the dominant form on the market, and in some places it still is. For example, Norwegians will tell you about being able to run down to the nearest gas station and grab a cake of yeast.
It’s not fundamentally that different from the dried product, being a pure culture of saccharomyces cerevisiae, but in this case much of the excess liquid is removed and the yeast pressed into a firm, but still wet, cake. It has a short shelf-life – it lasts a few weeks in the refrigerator.
I really love baking with fresh yeast. Like active dry yeast, it should be added to some of the liquid in the recipe and allowed to bloom a little. But it does seem to get going more quickly. It smells “yeastier” while it’s rising and baking, and does have a subtly better flavor.
I try to buy it when I can get my hands on it, and put it in the freezer, cut into 2 oz blocks, because that’s how I usually use it. When I’m ready to bake, I thaw one in the refrigerator and go.
Sourdough
Ah, sourdough. The darling of both the internet and the homesteading movement. What is it? It’s really just a perpetual culture of captured wild yeasts and bacteria that are capable of providing the leavening source for breads.
To hear enthusiasts talk, you can make anything with sourdough. And you probably can. Although it will sometimes have trouble leavening very enriched doughs. And I have never quite worked out the point of using sourdough “discard” to make things like cookies and brownies, which are not yeasted products to start with.
It’s claim to fame is producing lean, tangy, chewy, crusty “real” sourdough. And it’s excellent for that. A baker who is well practiced with sourdough can manipulate ingredients, temperatures, handling, and times to emphasize or de-emphasize all of these characteristics.
And while different sourdough cultures will have slightly different behaviors and flavors or textures – there probably isn’t anything earthshaking about that “200-year-old Gold Rush” starter.
Home Grown Yeast Culture
What is a home grown yeast culture? Just that. A culture that captures yeasts at home, used in place of commercial yeast products, or along with them.
How, you might be wondering, is this different from sourdough? They’re peas in a pod, in some ways. A home grown culture also involves capturing wild yeasts, but not usually on just grabbing them from the air or grains. Most home cultures are made starting with a yeast-rich source like clabbered milk, grape skins or apple peels.
Home cultures are fed and adapted to use in daily baking, and are selected more for their speed of rise. Because we’re not interested in developing sour flavors, long ferments and overnight retards are not used. While home cultures are likely to have some lactic acid bateria (and that’s good – they help keep the pH a little lower and reduce the risk of contamination) they don’t predominate, which tends to make care and maintenance a little easier.
I promise a post or two on how to make a home culture, and exactly why and how they’re different from sour dough.
Brewers Yeast
The “honorable mention” position goes to brewer’s yeast. The actual yeast used for brewing beer and wine – not the nutritional yeast you can get at the health food store.
Yes, you can bake with this. Though it doesn’t make a lot of sense to pay the premium for either the packets or tubes of brewing yeast, just to dump it into a batch of bread. Especially since these yeasts are adapted to fermenting fruit juice or wort, not bread. They can do it, but not as efficiently as baking yeast.
Now, if you live in a house with a home brewer, and you have easy access, that’s a different story. I experimented with it quite a bit when my husband made beer, inspired by historical recipes. If you try it, you’ll have to get your brewer to grab you out some fermenting wort while it’s still in it’s most bubbly and active state. Replace the liquid in your recipe with the wort, and expect rise times to be longer than for commercial yeast.
Do NOT wait till the beer has been racked off and use the mass of dead and dying yeast at the bottom. The bitter flavor will be pronounced.
So which yeast should you use?
Commercial yeasts allow for consistency. For the most part, rise times for a given recipe will be reasonably consistent, so long as things like temperature and humidity are also stable. The flavor they impart is very neutral. They’re eminently reliable. They can also get expensive, because you must buy a fresh culture every time you bake.
Dry yeast is available at most grocery stores. Although if you bake a lot, it’s probably a better idea to get a larger, vacuum-packed brick at a bulk retailer like Costco or Gordon Foods. Once you’ve opened the brick, store the remainder in an airtight container in either the fridge or the freezer. If you bake quite a lot, and you divide your products between sweet doughs and leaner, low sugar doughs, it is probably worth it to keep both the “gold” and regular yeasts on hand.
Cake yeast is much harder to find in quantity. But it’s widely used in commercial bakeries. So it might be worth stopping off at your local bakery and asking them to sell you a couple of bricks for home use. If you are polite (and even better, if you are a regular customer of their products), they may be willing. Or perhaps they will share their own source with you.
It IS possible to buy cake yeast by the 1 lb block online. But the shipping can sometimes make this option cost prohibitive. It’s a perishable product, so if it has to go very far, or in hot weather, you’ll probably be paying to ship it with ice pack and maybe overnight. One source for this is Scandinavian Butik.
Sourdough cultures can be made in your own kitchen – lots of tutorials for this already exist. Or you can purchase one. As I say, their specific behavior and flavor will vary a little. But every culture is going to attenuate to life in your kitchen, anyway. Whatever culture you start or buy, within a few dozen feedings will have picked up some of whatever wild yeast live in your kitchen. And the other populations of bacteria and yeast will rise or fall based on the conditions. Some like frequent feedings, some will predominate if you feed LESS frequently as the lower pH allows them to out-compete some of their neighbors. I thoroughly enjoy the cultures I’ve bought from Positively Probiotic. But I usually only keep one running at a time. The only reason to maintain more than one is if you prefer to have a wheat culture, another attenuated to rye, or perhaps even one that’s gluten free.
Right now, sour dough is trendy. Although a lot of what is promoted as “sour dough” online, probably isn’t really. It IS however, a way to maintain a yeast culture you don’t have to keep buying. It’s a bit fussy, and takes advance planning. A sour dough bake may take place over 1-3 days, depending on the recipe. It’s also somewhat more suited to lean doughs, and can struggle to properly leaven sweet or heavily enriched doughs.
I’ll talk more about creating, maintaining, and baking with a home grown yeast culture in another post. Suffice it to say, it’s a bit of a middle ground between commercial and sour dough cultures. You can keep a perpetual home yeast culture, that will leaven things more quickly than most sour dough recipes. It will have a milder, more neutral flavor. And it fits in well with a sustainable, “use what you have” farmstead kitchen.
Brewer’s yeast? Well, I leave that bit of experimentation up to you. It’s fun. And it harkens back to the popularity of “beer bread” recipes. But it’s probably only of practical use to those of you who have an active home brewer in the house – who also doesn’t mind fishing you out some of the fermenting wort to bake with. Some brewers don’t like to do this, because it can risk contamination of the beer.
Don’t forget to share your thoughts on your favorite type of yeast to bake with in the comments:
