The carotenogenesis in the endocarp and flavedo of Navel oranges over four consecutive maturity stages was assessed by HPLC-DAD-APCI-MS n . After optimizing the extraction method, a total of 77 carotenoids including 26 mono-and 33 diesters of violaxanthin, β-citraurin, and antheraxanthin was characterized. Whereas chloroplast-specific pigments such as (all-E)-lutein and (all-E)-β-carotene predominated in the flavedo of green-ripe fruit, a highly complex pattern of xanthophyll esters was found in the mature oranges. Total carotenoid contents of flavedo were approximately nine-fold higher (12,605 μg/100 g of FW) than those in the endocarp (1,354 μg/100 g of FW) at fully mature stage. The mature endocarp abundantly contained violaxanthin mono-and diesters, in addition to diverse antheraxanthin esters, which were exclusively detected in this fruit fraction. Likewise, β-citraurin esters were found to be unique flavedo constituents of mature fruit. Therefore, they may support the detection of fraudulent use of peel fractions during orange juice production.

Corn (Zea mays L.) growth and development is often limited by the availability of phosphate. We thus hypothesized that phosphate fertilization may increase the contents of (poly)­phenols, carotenoids, and tocochromanols (vitamin E) in corn grains. Corn plants cultivated on a soil fertilized with 44 kg phosphorus/ha were compared to plants grown on soil with low plant-available phosphate (1.6 mg CAL-P/100 g of soil), each sown early (April) and late (May) in a randomized field experiment. HPLC-DAD-(HR)-ESI-MS n revealed 19 soluble and 10 insoluble (poly)­phenols, comprising phenolic acids, phenolic amines, diferulic, and triferulic acids in corn grains. Contents of individual (poly)­phenols, carotenoids, and tocochromanols in whole grains were significantly (p < 0.05) increased by sowing time, but not by phosphate fertilization. In conclusion, low phosphate availability did not impair the biosynthesis of (poly)­phenols, carotenoids, and tocochromanols in corn grains.

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