Quick answers
What's a normal end-of-ferment pH for sauerkraut?
Between 3.3 and 3.6.
How long does it take to reach pH 4.6?
At 2% salt and 68°F, normally 24–48 hours. If it's still above 4.6 after 72 hours, something is off.
Guide
pH 4.6: the lacto-fermentation safety threshold
The 4.6 pH threshold is not arbitrary — it's the point below which Clostridium botulinum cannot produce toxin. Every major food-safety authority (FDA, NCHFP, Health Canada) uses it as the safety gate for acidified foods. This guide covers how to measure pH at home, what thresholds mean for different ferments, and what to do if a batch doesn't acidify properly.