Chinotto fruits and “chinotto” soft drinks: nutraceutical potential and authenticity control

Citrus myrtifolia is a Citrus plant, belonging to the Rutaceae family, commonly known as chinotto. It is cultivated mostly in Italy (Liguria, Tuscany, Sicily and Calabria) and, to a definitely lesser extent, in southern France, Malta and Libya. Although Citrus myrtifolia trees are often grown only for ornamental uses, their small yellow-orange fruits have an important impact on the food industry: the fruits are sour and bitter and for this reason they are used in the candy industry, in the preparation of jams, digestifs and aperitifs. Above all else, Citrus myrtifolia fruits are the primary ingredients of the so-called “Chinotto” Italian soft drink. Recently we determined some bioactive amines in different parts of Citrus aurantium fruits and in dietary supplements and the interesting results obtained from those analyses prompted us to broaden the research to other Citrus fruits and related commercial products. In light of the growing distribution of popular “Chinotto” drinks, which are also beginning to appear in several other countries (USA, Australia), it is surprising that chinotto is among the least studied Citrus fruits, with only a few reports present in the scientific literature. Taking into account this lack of sound information and the relevance of chinotto juice in the beverage industry, a new analytical method is hereby proposed for identification and quantitation of several active compounds in Citrus myrtifolia fruits and in commercial Italian “Chinotto” soft drinks, by liquid chromatography coupled to spectrofluorimetric detector (LC-F) and to mass spectrometry (LC-MS/MS). The LC-F system takes advantage of the native fluorescence possessed by the analytes to achieve high sensitivity and the LC-MS/MS technique allows an accurate identification, providing also a good selective quantitation. The aim of the study is the qualitative and quantitative analysis of coumarins (auraptene and umbelliferone), aminoacids (tryptophan), flavonoids (hesperetin, naringenin, myricetin), phytohormones (melatonin), organic acids (ferulic acid, caffeic acid) and other active substances in Citrus myrtifolia fresh fruits from Savona (Liguria, Italy) and in some commercial “Chinotto” drinks available on the Italian market. The analysis of the fruits allows one to determine the content in active compounds and therefore to assess their potential nutraceutical power. Moreover, this makes it possible to identify the main markers to be searched in “Chinotto” drinks where the presence of Citrus myrtifolia extract is claimed, to carry out a kind of authenticity control and certify the quality of commercial products. The methodology is thus proposed as a useful and promising analytical tool to monitor the entire supply chain and to safeguard quality and genuineness of Italian niche products, like chinotto fruits and “Chinotto” soft drinks.