I have been researching on E227 (Calcium Bisulfite), and could find minimal information about how it acts as a preservative and how effective it is. I could only find that it preserves by converting itself to sulfurous acid in an acidic liquid, but could not find out how effective and how exactly it preserves. I would appreciate any help.

• It is a reducing agent and preserves by reacting preferentially with any oxidising agents present – Waylander Sep 12 '18 at 14:35