This one's about yeast
I remember learning about yeast as a kid and being simultaneously fascinated and distressed. “It’s alive?” I would ask over and over. “And then we’re killing it?” (This preoccupation with eating living things perhaps foreshadowed my adoption of vegetarianism years later.) As I understood it, the little yeasts were asleep, then we woke up them up and let them gorge themselves, and then killed them in the oven. Their dying gasps let out air bubbles that made the bread rise. I did not like this image. I didn’t see why we couldn’t just use baking powder instead.
Many years later, grown-up, baking all the time, and basically I got it all right back then. Yeast is a living single-celled organism that is a member of the fungus kingdom. They’re everywhere, on plants and grains and on your skin right now. You can capture wild yeast to bake bread. Those methods usually focus on fruit, where they’re present in high volume because of the sugar. Sourdough starter is just yeast captured from flour plus the bacteria lactobacillus.
The commercial yeast you can buy (sometimes) from the store is a synthesized version that is then formed into granules with live cells enclosed in a jacket of dry, dead cells. Instant yeast is made up of smaller granules than active dry, so it dissolves and activates faster. What that means for baking is that active dry needs to be dissolved in liquid first, whereas instant yeast can be added straight to flour. There also tend to be more live cells in instant yeast, because it’s processed at a lower temperature, so if you’re converting a recipe from one type of yeast to another, just use 20% more active dry than you would instant. (By the way, I’ve had a few conversations now with baking pros and all of them swear by either instant yeast or fresh, never active dry.)
When you let bread rise, what’s happening is that the yeast is eating up all the sugar in your dough and expelling bubbles of carbon dioxide and ethanol. It can also multiply during that time. So even if you start with just a tiny amount of yeast, if it has enough sugar and a long enough rising time (e.g. overnight), it’ll replicate and eventually produce enough gas for your bread to rise. The only other factor to consider is temperature, since yeast is more active at higher temperatures. Putting your bread in a warm spot to rise, as in the challah recipe below, speeds it up, while leaving it in the fridge means that you can let bread rise over the course of a night.
I learned some of this after overproofing a batch of buns a few weeks ago. Here were some of the symptoms: 1) on opening the container in the morning I got a very strong whiff of alcohol, 2) the buns didn’t rise a whole lot, they ended up a bit flat, and 3) they stayed pale instead of browning during baking. The main reason for all of this is that I used too much yeast. I was using fresh yeast, which is basically yeast cells living in a wet, starchy cake. I followed a volume conversion online that turned out to be way off (I’m still working on the right one, but something like 2:5 dry:fresh seems to be in the ballpark). Too much yeast meant too much ethanol was produced, which gave it that alcohol smell. The gluten network that gives the dough structure was also weakened because there was so much gas, which is why the buns collapsed. And finally, bread crust gets browned in part because of the Maillard reaction which requires sugar, but the yeast had eaten all the sugar. It was hard to rescue those buns, which were still okay despite being pale and flat, but in subsequent weeks I added less fresh yeast and more sugar, and the buns got fluffier and golden-brown.
I eventually got over my distress about killing yeasts and eating their dead bodies. It would’ve been a tough road ahead to avoid killing anything in order to eat (just wait till I found out about figs). I still baked primarily with baking powder and soda for years though, because I thought of yeast as too fussy. It really isn’t. As long as you don’t kill it by leaving it somewhere over 140° F, and if you stick generally to the right amounts and rise times, it usually works out and doesn’t take that long. Nothing can beat the smell of rising yeasted dough or the bready taste it brings to your baked goods. It means comfort, to me. And we could use some of that.
What I’m reading
Anthony Falco, international pizza consultant
The key is just to fuck around, but take notes and use precise measurements.
This isn’t something I read, just something I heard during a Zoom chat with cooking-minded people (Anthony was a “special guest” last week and told me some of these things about yeast). I thought it was a pretty great summing up of baking or cooking in general. I’ve gotten as far as I have with cooking by doing the fucking around bit, but only since dedicating myself to getting better have I started taking notes and (sometimes) measurements. Now I try to jot down what I did for almost every meal, at least if it was good. If it wasn’t good, I try to think about why and what I could have done differently. It’s not a vast change from how I was cooking before, but I think slowly it’s making me better.