Identification of β-carotene oxidation products produced by bleaching clay using UPLC-ESI-MS/MS

The removal of plant pigments such as β-carotene is an aspect of vegetable oil processing often desired by the food and pharmaceutical industries. Adsorption of β-carotene to acid-activated clay (AAC) is a well-established method for purification. Despite this, the removal mechanism of β-carotene is not well understood. UPLC-MS/MS analysis of surface compounds extracted from β-carotene-AAC (BC-AAC) complexes show that AAC acts as an oxidiser. Oxidation products detected included canthaxanthin and 3',4'-didehydro-β-caroten-4-one. AAC had surface water exchanged with an ¹⁸O labelled water and was then exposed to β-carotene. Carotenoids labelled with ¹⁸O were produced from this reaction, suggesting surface water is necessary for β-carotene removal.