Morphological Characterization, Polyphenolic Profile, and Bioactive Properties of Limoncella, an Ancient Mediterranean Variety of Sweet Citrus

Limoncella of Mattinata, a rare and ancient Mediterranean citrus fruit, was investigated by sequence analysis of the ribosomal internal transcribed spacer regions, which assigns it as a variety of Citrus medica L. Morphological, chemical, and biomolecular approaches, including light and electron microscopy, HPLC-ESI-MS/MS, and antioxidant and anti-inflammatory assays, were used to characterize the flavedo and albedo parts, usually rich in bioactive compounds. The morphological findings showed albedo and flavedo cellular structures as “reservoirs” of nutritional components. Both albedo and flavedo hydroalcoholic extracts were rich in polyphenols, but they were different in compounds and quantity. The flavedo is rich in p-coumaric acid and rutin, whereas the albedo contains high levels of hesperidin and quercitrin. Antioxidant, anti-inflammatory, and genoprotective effects for albedo and flavedo were found. The results confirmed the health properties of flavedo and highlighted that albedo is also a rich source of antioxidants. Moreover, this study valorizes Limoncella of Mattinata’s nutritional properties, cueing its crops’ repopulation.