Quantitative Determination of β-Carotene Stereoisomers in Fresh, Dried, and Solar-Dried Mangoes (Mangifera indicaL.)

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Abstract
A rapid method for quantitative determination of β-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 β-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-β-carotene, respectively. Isomerization was shown to depend on the drying process. Whereas conventionally dried mangoes were characterized by elevated amounts of 13-cis-β-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 β-carotene stereoisomers and ranged from 113 to 420 and from 425 to 1010 RE/100 g for fresh and dried mango slices, respectively. Keywords: β-Carotene; trans−cis-isomerization; vitamin A value; mango; Mangifera indica L.; drying