A dear professor of mine in the Department of Viticulture and Enology at University of California at Davis used to say, while pointing down at his wooden podium, “Technically, you can ferment anything, even this tabletop here.” Smirking slightly he added, “Provided you can find the right micro-organism to do it.”
What Dr. Kunkee was trying to point out was that while none of us would try to make a drinkable wine out of wood, there are certainly micro-organisms out there that can use some of the carbohydrates in wood (and almost anything else) as an energy source. These microbes might not be able to survive on wood alone and they might have a really complicated enzymatic pathway that allows them to break down the wood into useable bits. However, given the right conditions and the right organism, it just might be possible to technically “ferment” wood (or dandelions, grass clippings or elderberries for that matter).
This is an example of the academic definition of “fermentation”, which sometimes gets lost in the shuffle of everyday winespeak. Talk to a knowledgeable microbiologist and she will tell you that fermentation is “a microbially-brokered metabolic breakdown of a nutrient molecule through an energy-yielding pathway” . . . or something to that effect. In plain English, if a bug (bacteria or yeast) eats something, gets energy from it and excretes something else out the other end in the process, you’ve got fermentation.
The conversion of sugar to alcohol, as in winemaking, is the hands-on model with which most of us are familiar. Lucky for us wine lovers, it’s also a fermentation that tends to have pleasant results. If you present the right microbe (say your typical Saccharomyces cerevisiae wine yeast) with the right set of conditions (say, a freshly-pressed barrel of 22% sugar Chardonnay grape juice) you’ll end up with an aqueous solution of acid, aromatic compounds and about 11% alcohol — in other words, wine.
Other fermented beverages include beer and sake, while cheese, olives and even some sausages and deli meat are considered “fermented” when defined in the non-booze-centric sense. Cheese is simply what results when bacteria turn the lactose in milk into lactic acid, separating the liquid milk into solid curds. The famous dry-cured Fellino salami of Parma, Italy owes its tang to various strains of indigenous mold and bacteria. When we talk about the “secondary fermentation” or “malolactic fermentation” we really mean the common metabolic process through which bacteria eat the naturally-present malic acid in wine and spit it out as lactic acid. Even if it’s not yeast turning sugar into alcohol, it’s technically still called a fermentation.
The bottom line is that yes, you technically can “ferment” dandelions, elderberries, grass clippings and other such ingredients. They have sugars and acids that your friendly neighborhood bacteria, yeast and molds will love to munch on — just check out your compost pile to see some serious fermentation in action. When you’re looking for a certain end product and want it to be drinkable to boot, it’s important to select the right microbe for the job, give it the right starting conditions and carefully control the fermentation to help your microbe deliver the results you’re looking for.
Stripped to its essence, here’s how to make wine: Select your starting material with extreme care and get to know it intimately so you will know how it will respond to fermentation. Tweak that raw material if need be (and, if you’re a commercial winemaker, as the law allows) to enable a harmonious end result. Make sure that your starting material is only visited by “good” microbes that will get the job done in a healthy manner and do your best to help these microbes work in a healthy manner. Give only a gentle nudge when necessary and once the microbes have done their work, protect your new store of ephemeral fermented goodness from oxygen, light and bacterial scavengers that might harm it.