Vinegar production — the acetification of a fermented alcohol source by Acetobacter bacteria — is the most misunderstood fermentation in everyday cooking. Vinegar is not simply sour liquid; it is the product of a specific bacterial oxidation that produces acetic acid from ethanol. The quality of the vinegar is determined by the substrate (wine, apple cider, malt, rice), the acetification method (Orleans process: slow, with maximum complexity; submerged: fast, with less complexity), and the aging that follows.
- **The substrate:** Any alcoholic liquid can produce vinegar. The amino acids, phenolics, esters, and residual sugars in the substrate are preserved and concentrated in the vinegar — a high-quality wine makes a high-quality wine vinegar. - **Acetobacter requires oxygen:** The acetification is aerobic — unlike lactic fermentation, vinegar production cannot be done in a sealed container. The surface must have air contact. - **The mother (mother of vinegar):** The cellulose matrix produced by Acetobacter — similar in structure to a kombucha SCOBY. The mother seeds subsequent batches. - **Temperature:** 25–30°C optimal. - **Time:** Orleans process (slow): 4–6 weeks. The slow method allows the vinegar's esters to develop — the compound esters that give aged wine vinegar its complexity. - **The Maillard vinegar:** Noma's innovation — reducing vinegar with sugar until Maillard reactions produce a deeply complex, caramelised reduction with simultaneously sour, sweet, and Maillard characteristics.
Noma Fermentation