Identification of carotenoid isomers in crude and bleached palm oils by mass spectrometry

In this work, a method for identification of α- and β-carotene isomers in palm oil samples was developed by UHPLC-MS/MS. The fragmentation patterns of both isomers were studied and a diagnostic ion was assigned to α-carotene (m/z 388). The developed method was used to identify isomers in crude palm oils from two cultivars (E. guineensis, here so-called native oil and E. guineensis × E. oleifera, here so-called interspecific hybrid) and bleached oil with two types of commercial bleaching earths (neutral and acid activated). It was noticed that α- and β-isomers are present in both crude oils, nevertheless β-carotene is the most abundant. The reduction of α- and β-isomers in the bleached native oil was very similar after treatment with the two different types of adsorbents. For the interspecific hybrid oil, the acid adsorbent provided a reduction of the two forms, while the neutral adsorbent reduced mostly the β-form.