First, a quick science-y bit (but don’t worry, I’ll keep it painless). Sauerkraut is already preserved. It’s cabbage that’s been transformed by lacto-fermentation, which is just a fancy way of saying “good bacteria had a party and made everything sour and safe.” This process creates an acidic environment that hates bad bacteria.
Think of it like a moat around a castle. The acid is the moat, and your kraut is the king. That king is really hard to depose. So, unopened, store-bought sauerkraut in a jar? It can last months past its “best by” date. Seriously, check the date—then add a year.
Homemade kraut is a bit more of a wild child, but still tough. If you fermented it properly (under the brine, no floaty bits), it can last 4 to 6 months in the fridge. But here’s the kicker: it doesn’t spoil like milk. It just gets sourer and softer.
