What IS fermentation? For those who need an official version, here’s a handy definition from The American Heritage Science Dictionary:
“The process by which complex organic compounds, such as glucose, are broken down by the action of enzymes into simpler compounds without the use of oxygen. Fermentation results in the production of energy in the form of two ATP molecules, and produces less energy than the aerobic process of cellular respiration. The other end products of fermentation differ depending on the organism. In many bacteria, fungi, protists, and animals cells (notably muscle cells in the body), fermentation produces lactic acid and lactate, carbon dioxide, and water. In yeast and most plant cells, fermentation produces ethyl alcohol, carbon dioxide, and water.”
My own definition isn’t nearly as concise, and draws on my education in permaculture. I like to think of any given food as a blob of energy, nutrients and water. There are enzymes, fungi, and bacteria in and on the food that want to eat up the proteins and turn it into a moldy puddle – similar to what happens in a compost pile.
There are many ways that inventive humans have come up with to prevent our foods from becoming unsavory or inedible, preferably for as long as it takes us to procure the next source of calories (which may be only a few hours or several months).
The oldest methods involve placing the food into an environment (or creating that environment IN the food, as in fermented milk) that favors the growth of common micro-organisms with whom our guts have co-evolved. The group of Lactobacillus are probably the most famous, so named for the lactic acid they produce from sugar, namely lactose, and give their name to the term “lacto-fermentation.” In reality there are thousands of different species that all have roles to play at different stages of the preservation process.
These environments are:
• always acidic
• anaerobic
• usually at least somewhat (or very) salty
The organisms that prefer these environments leave the proteins in the foods intact, which means the foods mostly retain their original form and texture. The waste products from these organisms are acidic, and pathogenic organisms generally do not fare so well in acidic environments. By making the environment favorable to the beneficial microbes, we also make it unfavorable for pathogens.