Proper fermentation vessel selection — the Noma Guide's documentation of which vessels work for which fermentations — addresses one of the most practically misunderstood aspects of home fermentation. The vessel type affects the fermentation outcome: wide-mouth vs. narrow-mouth affects oxygen exposure; glass vs. ceramic vs. plastic affects trace mineral availability; airlocks vs. open-top vessels affect CO₂ management.
- **Weck jars (rubber gasket glass):** The Noma Guide's preferred vessel for vegetable lacto-fermentations. The gasket allows CO₂ to escape (the lid burps slightly as pressure builds) while preventing oxygen ingress. This passive airlock effect is the simplest practical solution to anaerobic fermentation management. - **Wide-mouth crocks (ceramic):** Traditional for large-batch kimchi and sauerkraut. The wide mouth makes packing and pressing easier; the ceramic is non-reactive; the weighted lid creates a passive anaerobic seal. - **Vacuum-sealed bags:** Used by Noma for rapid lacto-fermentations — removing all oxygen from the fermentation environment allows precise control but eliminates the natural CO₂ release that characterises traditional fermentations. - **The brine submersion principle:** Any lacto-fermented vegetable must remain submerged in brine throughout the fermentation — any surface exposure to air allows aerobic mold growth. Weights or improvised submersion devices are required.
Noma Fermentation