Fermentation — the transformation of food by microorganism activity — is the oldest food preservation technology and the source of flavour complexity that no cooking process alone achieves. Understanding the three primary fermentation pathways used in culinary production (lactic acid fermentation, acetic acid fermentation, and alcoholic fermentation) provides the framework for understanding miso, soy sauce, vinegar, cheese, bread, wine, beer, kimchi, tsukemono, and every fermented product in the database.
**Lactic acid fermentation:** - Organisms: Lactobacillus species (bacteria) - Input: sugars (glucose, fructose) - Output: lactic acid - Result: sour flavour, preservation through pH reduction, texture changes (protein denaturation by acid) - Applications: yogurt, sour cream, crème fraîche, cheese, kimchi, sauerkraut, dill pickles, sourdough bread, miso (alongside koji) - Optimal conditions: 18–22°C for slow, complex fermentation; 30–35°C for faster development. Anaerobic (oxygen-free) environment preferred. **Acetic acid fermentation:** - Organisms: Acetobacter species (bacteria) — require oxygen - Input: ethanol (from prior alcoholic fermentation) - Output: acetic acid (vinegar) - Two-stage process: first alcoholic fermentation produces ethanol; then Acetobacter converts ethanol to acetic acid - Applications: all vinegars (wine vinegar, rice vinegar, apple cider vinegar, balsamic) - Quality indicator: the mother of vinegar — the mat of Acetobacter that forms on the surface during traditional production **Koji fermentation (Aspergillus oryzae):** - Not strictly listed in the three types above but essential to Japanese cooking - Produces amylase (converts starch to sugar), protease (converts protein to amino acids = umami), and lipase (converts fats to flavour compounds) - Applications: sake, miso, soy sauce, mirin, shio koji, rice vinegar - The critical distinction: koji is the enzyme factory that enables secondary fermentations **Alcoholic fermentation:** - Organisms: Saccharomyces cerevisiae (yeast) - Input: sugars - Output: ethanol and CO₂ - Applications: wine, beer, spirits, bread leavening, sake (alongside koji)
Modernist Cuisine Vol. 2