Photolysis of Alpha-Tocopherol in Olive Oils and Model Systems.

The photolysis of a-tocopherol (I) in olive oil (O) and in some model systems [n-hexane=H; anhydrous n-hexane=HA, and triolein=T] was studied under sunlight and under artificial light (lambda>290 nm) by HPLC and GC-MS. In O and T, I disappeared linearly until the 50% of the starting concentration, reached a constant value, and finally disappeared rapidly from the medium. In the model system, photolysis followed a pseudo first order kinetics. While no peaks attributable to photoproducts were found in O, a main product identified by 1H, 13C NMR and GC-MS as 5-formyl tocopherol (II) was found in the model system. Irradiation of compound (II) led to species undetectable by HPLC in agreement with a slower consecutive kinetic process than that of I. In the HA and T systems, the formation of (II) occurred at lower levels than in H. The possible behaviour of photodegradation is discussed.

PIRISI F.M.;  ANGIONI A.;  BANDINO G.;  CABRAS P.;  MACCIONI E.;  RENIERO Fabiano;  GUILLOU Claude Gualbert; 

1998-10-05

JRC17060