RESUMO
The carotenoid pattern of mango cv. 'Kent' was investigated by LC-(APcI)MS analyses. In solvent extracts from the mesocarp an unusual carotenoid ester was identified as violaxanthin dibutyrate. For unequivocal identification of butyric acid by an independent method, total lipids were isolated by solvent extraction from the fruit flesh and analyzed by GC after saponification and subsequent methylation. Thus, evidence of butyric acid (1.6 area%) was provided. To the best of our knowledge, this is the first report on a xanthophyll dibutyrate in plants. Additionally, further carotenoid peaks were tentatively assigned to 9-cis-violaxanthin and neochrom or luteoxanthin, respectively, by their UV/vis and MS data of the saponified extracts.
Assuntos
Carotenoides/química , Carotenoides/isolamento & purificação , Frutas/química , Mangifera/química , beta Caroteno/análogos & derivados , Ácido Butírico/análise , Ácido Butírico/química , Cromatografia Gasosa , Cromatografia Líquida de Alta Pressão/métodos , Ésteres/química , Ésteres/isolamento & purificação , Ácidos Graxos/análise , Lipídeos/química , Espectrometria de Massas/métodos , Pigmentos Biológicos , Extratos Vegetais/química , Espectrofotometria Ultravioleta , Xantofilas/química , Xantofilas/isolamento & purificação , beta Caroteno/química , beta Caroteno/isolamento & purificaçãoRESUMO
A rapid method for quantitative determination of beta-carotene, including cis-isomers, in dried mango has been developed. Applicability of available methods to dried products was limited because of formation of artifacts caused by extraction and preparation. The analytical procedure was based on the extraction of carotenoids from dried mango mesocarp using a mixture of methanol and acetone/hexane, allowing the separation of disturbing fibers. No saponification was required. Furthermore, carotenoid determination by HPLC on a C30 stationary phase was achieved. This method was applied to determine beta-carotene and its stereoisomers in fresh, dried, and solar-dried mango slices of four cultivars. Drying resulted in a complete and partial degradation of xanthophylls and all-trans-beta-carotene, respectively. Isomerization was shown to depend on the drying process. Whereas conventionally dried mangoes were characterized by elevated amounts of 13-cis-beta-carotene, solar-dried mango slices contained additional amounts of the 9-cis-isomer. Calculation of vitamin A values was based on the real amount of the beta-carotene stereoisomers and ranged from 113 to 420 and from 425 to 1010 RE/100 g for fresh and dried mango slices, respectively.