By law, butter must contain at least 80% fat, making it highly susceptible to rancidity. When stored in cooled conditions of 3-5°C, it will turn rancid in 2-3 weeks. Shelf life can be extended to 6-9 months by deep freezing (-20°C).
Butter can oxidize both by metal ion catalysis which gives rise to “fishy” taints, and by photo-oxidation which is often due to non-foil wrapped butter being stored near fluorescent lighting in a refrigerated display.
Synthetic antioxidants (BHA, BHT, propyl gallate) and metal chelators (citric acid, phosphoric acid, salts of EDTA) have proven effective in inhibiting oxidation, but use of these compounds in butter is not permitted in the USA, EU and most other countries. So, butter is not treated with any antioxidant, but rather is refrigerated to prolong shelf life.
|
