How does fermentation preserve food?
Answer: Naturally! Generally speaking, when bacteria, yeasts, and molds ferment food substrates, they produce various by-products. Some of these by-products act to preserve the fermented food by either killing off pathogenic or spoilage bacteria and fungi, and/or by reducing the pH to create an inhospitable environment for these unwanted microorganisms. Examples of such by-products are organic acids (lactic, acetic, formic, propionic), ethanol, carbon dioxide, diacetyl, reutrin, and bacteriocins.
For our products, lactic acid bacteria (LAB) are at work, doing much of the preservation. The addition of brine creates a salty, no oxygen environment that is ideal for LAB, but which inhibits many other unwanted microorganisms. The LAB then get to work, fermenting the carbohydrates in the food, producing various by-products that further help to naturally preserve food. One of the main by-products is lactic acid. Other by-products are antimicrobial peptides, otherwise known as bacteriocins. These acids and antimicrobials create an environment that only the good, probiotic bacteria can tolerate, killing off or inhibiting the growth of spoilage and pathogenic microorganisms.
Fermenting bacteria are not the only source of antimicrobial substances, however. Cabbage and other brassicas have naturally occurring, antimicrobial chemicals that inhibit the growth of unwanted bacteria.
For a more detailed look into the fermentation process, check out the Info page, Fermentation Overview.