Yeast and bread making?

Yeast makes bread rise, so “higher” is an odd question. Without yeast, it won’t rise, period. Well, unless you are making a “quick” bread with baking powder and/or baking soda as leavening. Or a puff pastry which is leavened by simple steam. But making a yeasted bread rise higher using yeast? An odd question, to be sure! Here are some tidbits that might point you in the right direction. I hope…

If you let it rise as high as raw dough will allow, the loaf will collapse upon baking, because the raw dough is like a balloon being stretched by the pressure inside. Add heat, the rubber melts, suddenly no balloon. Bread is similar, the gluten structure has to be able to hold its shape as heat is applied, so you don’t want to let it over-rise.

If you let it rise the appropriate amount, a loaf will add a small amount of “oven spring” which is primarily the water and alcohol turning to gas and expanding the air pockets in the heat. Oven spring can add up to 25% to the loaf volume, though that much is rare. 10%-15% is closer to normal.

So, again, how to make bread rise higher with yeast? Well…you can make it rise FASTER by keeping the temperature of the bread higher, OR by giving the yeast more simple sugars to feast (yeast can use the starches of the flour as food, but must first use enzymes to break the starches into the simple sugars), OR by adding more water, OR by adding more yeast. BUT…

Keeping the temperature too high (around 100F is great for yeast, much higher will kill it, lower retards growth) will weaken the gluten network, so you may get a collapsed loaf…i.e. not higher.

A little sugar will help the yeast grow faster, but we still aren’t talking about a taller loaf. And adding too much sugar will prevent proper gluten network (or fabric, however you wish to describe it) formation, which in turn will not trap gas as well…thus, not higher.

More water (to a point) is great for both yeast and gluten formation, but means a less structured, more “open” gluten network, which is fine for free-form breads, but will collapse loaf-pan breads. And too much water makes a batter, which is fine for chewy pancakes…but none of these really makes a “higher” loaf.

Lastly, more yeast means faster rise, but if you let it go too long, you have an over-rise and collapse. Just shy of that, you may still get a collapse because so much yeast produces a lot of alcohol, which also weakens the gluten network.

So…to make a taller loaf, you need the *correct* amount of gluten formation (good flour and enough water, so not a yeast issue), the right amount of food for the yeast, the right amount of time (which depends on the food provided for the yeast and amount of yeast), and the right amount of water (enough for BOTH gluten and yeast). Too little of any one of those means a shorter loaf, too much means an over-rise and collapsed loaf. Basically, to make the tallest possible loaf, you have to get it ALL correct. It is both an art and a science, there is leeway, just not much.

Oh, I forgot about salt. Salt strengthens the gluten and slows yeast growth. Too little (or no salt at all) means a faster rise, but not taller. The right amount of salt (around 2% by weight, which is also about normal taste-wise, too) strengthens the gluten and lets the yeast do its job (if slightly slower), so here you may get a tiny smidgen taller loaf, but we are talking a small amount, not the silver bullet of tall loaves. And too much salt retards (up to 3% or thereabouts) or even kills (> 4%) the yeast.

Last bit (I could go on and on, if you hadn’t guessed). Fats. Liquid fats reduce gluten network formation, but solid fats don’t. Yeast don’t care, so long as you don’t try to replace water with fat. Yeast doesn’t eat fat, and gluten doesn’t form using fat, so you must have water. But a loaf made with lard or hydrogenated oil or solid veggie oil (such as palm oil) can rise notably higher than the same recipe made with no fat at all, or made with liquid oils. Oh, and you have to treat butter (drum roll) as a liquid, because it has such a low melting point!

So…you can make bread rise faster, but not really higher (specifically in terms of yeast). The question is kind of nonsensical.

Crud, I had another thought. Sorry. A recipe made at sea level will rise higher if made at higher elevation, due to lower air pressure. An over-rise situation will usually occur because gravity hasn’t changed much, so you use less yeast. Now…THEORETICALLY…a loaf made in microgravity (like in the space station) would expand until it blew like an over-inflated balloon. So, maybe you could make a taller loaf in low gravity. But I guess that still isn’t the yeast, is it? Never mind.

I hope you find something useful in all this drivel