Sodium Benzoate, Benzoic Acid
Benzoic acid is naturally found in gum benzoin but also occurs in honey and dairy products. Its salt, sodium benzoate, is water-soluble and is well-suited as a preservative in cosmetics and food. Both ingredients inhibit the growth of yeast and mould, as well as having slightly antimicrobial properties.
see Heike Käser 2010, "Naturkosmetische Rohstoffe", Linz, Verlag Freya, 3. Edition 2012