Not kosher
Description: Nisin (preservative)
Function: preservative
Rationale:
Nisin is generally regarded as parve when properly certified, but is produced by fermenting Lactococcus lactis on media that can be milk- or peptone-based; multiple suppliers explicitly market 'kosher certified' nisin, implying uncertified nisin's status depends on verifying the growth medium, so retaining not_kosher (requires reliable certification) pending verification.
If you don't see a status above, it does not mean the additive is not kosher automatically - it might just not be documented in our database yet.