Tomorrow morning we head off to Vermont for the New York Mycological Society’s annual chanterelle foray, and I’m very excited. Now I realize that to many of you the idea of excitement about mushrooms is about as reasonable as dinner with an ax-murderer, so I have to say – I have no idea what caused the attraction, but I find mushrooms as weird, varied and charming as the human population.
But mushrooms are but a part of this weekend. I get to hang with like-minded folks, many of them long-term, dear friends. And I get to eat. And cook.
The weekend would not be complete without me making buckwheat pancakes for Saturday breakfast. The recipe was handed down from my mother’s mother (who I never met, she died in 1935). I’ve adapted it to be gluten free.
This is an old-fashioned recipe, and requires a yeasted sponge, which sits overnight bubbling and becoming sour. In the morning one adds baking soda to the blend, then greases the skillet and griddles away. Sometimes the nighttime ferment goes slightly out-of-hand and the batter plays Vesuvius, usually about 2 AM. Well-tuned ears have heard a glop of it slap to the floor. My friend Claudine refers to the process as “Those pancakes that walk out of the bowl.”
Such a power in leavens! And yet, so much mis-information and ignorance. Recently I’ve read so much online chatter about them I thought it might be good to set the record straight.
Leavens are substances that cause breads, cakes and pancakes to rise. Basically they produce gas, which is captured in the structure of a baked good. Oven heat renders this inflation permanent by solidifying the structure.
We like eating leavened foods because they feel good in the mouth. There’s also a taste to leavening agents (often a so-called “acquired taste”) that many find appealing.
There’s two general categories of leavens, chemical and biological. Baking soda/baking powder is the first, yeasts are the second.
Baking soda is a potent alkali. Adding it to an acidic liquid creates a vigorous reaction, including the creation of CO2 gas. Baking powder is mostly acidic. Together the two react once they get wet. In a wet, sugary, protein-rich environment, like cake dough with eggs and milk, they produce lots of CO2 – especially when heated in an oven. (Chemical reactions proceed more rapidly as heat increases).
Baking soda by itself is a leaven when the dough is acidic, as is the case in buckwheat pancake batter that’s been over-fermented by yeast, time (overnight) and temperature (summer warmth). The batter, when hit with a small dose of baking soda, produces CO2, and a rise.
One thing to remember about baking soda + acid: Chemical reactions proceed rapidly and end suddenly. This is particularly true of acid+alkali reactions. If you’ve ever waited half an hour after mixing cake batter before putting it in the oven you know what happens – a doorstop. That’s because the chemical reaction has played out and the gasification is over. It’s also why most baking recipes call for the oven to be preheated and the cake to be inserted immediately.
Also, since the addition of baking soda to an acidic dough creates pH neutrality as well as gas, it’s easy to over-soda sourdough and end up with blandness.
Soda-based leavens are primarily found in sweet baked goods. When it comes to savory, the dominant leaven is biological.
|For this you've got to use yeast|
Yeast is our biological leaven friend, though “biologic” is a misnomer – “mycologic” fits better. (Mycology is the study of fungi.)
Yeasts are monocellular fungi. There’s hundreds of species and dozens of genus. When it comes to leavening, however, we use but a few.
Yeast leavens do the same thing as chemical leavens – produce CO2 gas. However they produce it through digestion, by ingesting sugars found in grains and “burping out” CO2. A yeast based gas production cycle is much longer and more complex than a soda gas production cycle, because as the yeast cells are digesting they’re also reproducing and producing alcohol as well as CO2. A small quantity of yeast might be all that is added to bread dough, but the food-rich dough provokes the yeast to reproduce. A yeast population produces its greatest amount of gas just before over-reproduction sets in. The trick for bakers is to seize that moment. Wait too long and the taste of dead yeast cells gives the bread an off flavor; bake too soon and the rise is insufficient.
Actually the situation is more interesting than I’ve just let on. CO2 production is a side effect of digestion, not the main activity. Yeasts break down complex carbohydrates as well as simple sugars, producing compounds we humans recognize as flavors. (Side note: This is the third kingdom’s environmental job. Ever see a tree covered with shelf mushrooms? Return in a few years and see what’s happened. Wood tissue won’t become soil by itself; fungi are necessary). The tastes we associate with bread are greatly aided by yeast digestion.
Which brings us to an interesting dilemma: As digestion continues, flavor production increases. Thus it behooves bakers to extend digestion as long as possible. However, for-profit production insists that “time is money”. It behooves investors to extend digestion as little as possible (to produce more product in the shortest amount of time). Thus baking divides between those who are after the most flavor versus those who are after the most profit.
Those in the former group will adjust the yeast in a recipe downward to the lowest possible amount in hopes of prolonging digestion. Those in the latter add as much yeast as they can – and then add sugars to boost speed. It’s CO2 they’re after, not flavor.
Commercial yeasts are all the same species of fungi Saccharomyces cerevisiae. The difference between dry, instant, and cake yeasts has to do with the number of yeast cells per unit measure. You can use these different forms interchangeably by adjusting rise times.
If speed over taste is a formulation you reject, there’s an alternative: wild yeast. To work with wild yeasts means capturing, cultivating and incorporating them as cultures. It’s a tricky process but not impossible, and it has the side benefit of producing a leaven with unique flavor.
But first an aside: There’s a lot of concern today about yeasts’ impacts on humans. In fact there are many fungi that can have a deleterious effect on us, causing problems from “jock itch” to such horrors as Blastomycosis. http://botit.botany.wisc.edu/toms_fungi/jan2001.html Fortunately, the yeasts used in baking are NOT the ones associated with human infestations. Nor does the presence of one yeast assure the presence of another. Mushrooms do grow on mushrooms (this is called a hypomyces, and is found in gourmet food with the lobster mushroom) but Candida albicans does not flourish better in an environment rich with Saccharomyces cerevisia.
Capturing wild yeasts is so popular an activity today there’s workshops as well as books and countless web articles on the subject. Basically it involves adding water to grain (usually wheat or rye), keeping the temperature right, and waiting. Eventually a complex community of microorganisms flourishes. This is a sourdough, so-called because the community includes bacteria as well as fungi, and the bacteria create sour-tasting acid.
A sourdough also works by digesting grains, but now the process is even more interesting. The yeast digestion byproducts feed the bacteria, and the acid environment the bacteria create retards yeast reproduction just enough to lengthen digestion to optimal times. Flavors created by sourdough leavening are greater in number as well as intensity than those made with commercial yeast. Seizing the right moment now involves taking pH measurements (to determine acidification) as well as watching time and temperature.
Exactly what species constitute wild yeasts, and exactly where these come from, is the topic of debate. While mycologists know that any cubic meter of sea-level air contains spores from every known fungi, they are also quick to point out that spores alone do not equal life. It may be that exposing grains + water to air captures floating yeast cells, or it may be that the cells were colonized on the grain and “liberated” by water. Also, since identifying yeast species is a job for specialists, bakers can’t say what their wild yeasts actually are. Instead we call them Saccharomyces exiguus: “existing” or “wild”.
The presence of variety in the yeast culture, as well as the absence of aggressive commercial yeasts, may be the reason people with reported yeast allergies find they can eat sourdough bread. However there may be another reason: Correctly done, sourdough fermentation is a long process – 8 to 12 hours. Many of the flour’s complex carbohydrates are digested over such an extended time. Thus the bread is pre-digested and therefore easier for the human gut to process.
It intrigues me that in this world of technology and change, leaven science isn’t exactly evolving. Sourdoughs were probably discovered about 5,000 years ago. Commercial yeasts came to dominance in the late 19th century, as did baking soda/powder. Basically there’s been no leavening agents invented since.
So when I sling batter onto the griddle Saturday AM, I’ll thank chemistry and mycology as well as family. And after filling myself and 15 good friends up with healthful, nutritious food, I’ll raise a knife and a paper bag to the mycology gods and say, “Bring on the goods.” Not single-celled yeastie beasties, but full-form basidiomyces:
|Chanterelles (top), Lobster mushrooms (center) and Sweet tooth (bottom)|