The carotenoid composition of strawberry tree (Arbutus unedo) fruits has been characterised in detail and quantified for the first time. According to the total carotenoid content (over 340 μg/g dw), mature strawberry tree berries can be classified as fruits with very high carotenoid content (>20 μg/g dw). (all-E)-Violaxanthin and 9Z-violaxanthin were found to be the major carotenoid pigments, accounting for more than 60%, responsible for the bright colour of the flesh of ripe fruits. In addition other 5,6-epoxide carotenoids, such as (all-E)-neoxanthin, (9'Z)-neoxanthin (all-E)-antheraxanthin and lutein 5,6-epoxide, together with (all-E)-lutein, (all-E)-zeaxanthin and (all-E)-β-carotene were found at high levels (>5-20 μg/g dw). The LC-MS (APCI+) analysis of the xanthophyll fraction in their native state (direct extract) revealed that most of them (>90%) were totally esterified with saturated fatty acids (capric, lauric, myristic, palmitic and stearic). Monoesters, homodiesters and heterodiesters of (all-E)-violaxanthin and 9Z-violaxanthin were the major pigments.
Keywords: (9Z)-violaxanthin (PubChem CID: 5282218); (9′Z)-neoxanthin (PubChem CID: 5282217); (all-E)-antheraxanthin (PubChem CID: 5281223); (all-E)-lutein (PubChem CID: 5368396); (all-E)-neoxanthin (PubChem CID: 5281247); (all-E)-violaxanthin (PubChem CID: 448438); (all-E)-zeaxanthin (PubChem CID: 5280899); (all-E)-β-carotene (PubChem CID: 5280489); Arbutus unedo L.; Carotenoids; Fatty acids; GC; HPLC–DAD; LC–MS (APCI+); Lutein 5,6-epoxide (PubChem CID: 5281244); Xanthophyll esters.
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