Monitoring the Changes in Phenolic Compounds and Carotenoids occurring during Fruit Development in The Tissues of Four Citrus Fruits

Abstract Citrus are fruit crops that are widely cultivated in Southern Italy. The phytochemical profile of citrus depends on the species, the tissue and the ripening stage. This study aimed to perform a comprehensive analysis of the phenolic compounds and carotenoids from four citrus species cultivated in the region of Sicily, Southern Italy, between and within the different tissues and the ripening stages. The selected species were pummelo [C. maxima (Burm. ex Rumph.) Merr.] cv. ‘Chandler’, lemon [C. limon (L.) Burm. f] cv. ‘Akragas’, and sweet orange [C. sinensis (L.) Osbeck] cvs ‘Tarocco’ and ‘Washington navel’. Fruits were harvested four times every five weeks from Sep 2018 to Jan 2019. At any stage, flavedo and albedo showed the highest contents of phytochemicals. Elevated levels of phenolic compounds, e.g., narirutin, were found in the flavedo of unripe lemon and ‘Tarocco’ orange (54.8 ± 8.15 and 248 ± 30.3 mg kg-1 dw, respectively). Narirutin decreased significantly (p