Stability of some phenolic antioxidants in fatty preparations

Stability of butylated hydroxyanisole (BHA), propyl gallate (PG), trihydroxy butyrophenone (THBP), tert-butyl hydroquinone (TBHQ) and a mixture of PG and BHA (1:1) in fatty preparations stored under three different conditions was studied. Each antioxidant was added to a fatty model to determine its degradation kinetics and its evolution during the oxidation of the fatty product. Their degradation was adequately described by a first-order kinetic process. An opposite relationship between the stability of antioxidants and their rate protection against oxidation of the fatty product was obtained. At 25 degrees C, t90 values ranged between 10 days for TBHQ and 61 days for BHA. On the other hand, compared when they were formulated alone, the increase of PG and the diminution of BHA degradation kinetics were observed. A degradation product arising from TBHQ was found in samples and stock solutions; an HPLC method for its identification is proposed with detection at 254 nm.