Analysis of Some Italian Lemon Liquors (Limoncello) VERSARI ANDREA, ² NATALI NADIA, ² RUSSO MARIA TERESA, ‡ AND ANTONELLI ANDREA* ,§ Dipartimento di Scienze degli Alimenti, Universita ` di Bologna, via Ravennate 1020, Cesena (FC) 47023, Italy, Dipartimento di Scienze e Tecnologie Agroforestali ed Ambientali, Universita ` di Reggio Calabria, P.zza San Francesco di Sales 7, Gallina 89061, Reggio Calabria, Italy, and Dipartimento Interdisciplinare di Scienze Agrarie, Universita ` di Reggio Emilia, via Kennedy 17, Reggio Emilia, 42100, Italy The chemical composition of several commercial Italian Limoncellos, lemon-peel-based alcoholic beverages, was studied by chromatographic techniques. These methods allowed a rapid monitoring of Limoncello, giving information on quality markers and possible adulteration of the product. Quantitative data for more than 60 compounds are reported. Limoncellos were characterized by the presence of selected volatile (terpenes, aldehydes, alcohols) and nonvolatile compounds (psoralens, coumarins, phenolics, carbohydrates and acids). On the basis of their composition, the samples were grouped by PCA analysis in two sets; the first group showed a composition similar to lemon essential oils, with a high content of b-pinene, myrcene, trans-a-bergamottene, and b-bisabolene, and a low content in neral and geranial. The composition of the second group suggested the occurrence of oxidative phenomena and/or the addition of flavors. The presence of ethyl acetate, acetaldehyde, 2-methyl-1-propanol and glycerol showed that a fermentation probably occurred in the sugar syrup used to dilute the Limoncello after the extraction process. KEYWORDS: Lemon liquor; composition; flavonoids; coumarins; psoralens; essential oils; chromatog- raphy INTRODUCTION Citrus peel (i.e., flavedo or hepicarp), a tissue rich in secondary plant metabolites and characterized by pleasant flavors, is commonly used for preparation of marmalades, candied peels, and essential oil (EO). In Italy, lemon peels are also used to produce a high-value product called Limoncello. Limoncello is a typical Italian lemon liquor obtained from the alcoholic extraction of essential oils from lemon peel (Citrus limon (L.) Burm. f.). This beverage is becoming increasingly popular in Italy and abroad due to its natural aroma and taste, which recall the fresh lemon, as well as for its digestive properties. A total production of 15 million liters of Limoncello per year is estimated (1). The production process is simple and includes the following main phases: (i) Washing and peeling the fruits. (ii) Infusion of the lemon peels in 95% ethyl alcohol for 2-7 days. During this phase, the extraction of essential oils and other peel constituents occurs. (iii) Dilution with a sugar syrup to obtain a final product with ca. 32% ethyl alcohol. (iv) Bottling the Limoncello. In the European Community, addition of natural or synthetic flavor/essential oil to the Limoncello is regulated by the Council Regulation No 1576 (2). Besides ethanol and water, Limoncello contains several volatile and nonvolatile minor compounds (ca. 2%), which are fundamental for its sensory characteristic. The former are ter- penic compounds, which form the EO, and the latter include several classes of nonvolatile compounds (Figure 1) with poten- tial health-related properties, such as flavonoids, coumarins, and psoralens (3-6). In addition to their remarkable olfactory and taste properties, these compounds may play an important role as markers for chemotaxonomic studies and for the evaluation of quality and genuineness of citrus juice (7, 8), fruit (9, 10), and EO (11). For example, coumarins and psoralens are helpful in detecting the adulteration of cold-pressed EO by the addition of steam-distilled oil, which lacks these volatile components. Literature mainly concerns the volatile fraction composition of Limoncello (12-15). Further data on the analytical charac- terization of Italian Limoncello are needed to protect the consumers and to draw guidelines for the quality control and the regulation of this industry. In this preliminary study, twelve samples were analyzed for their flavors, sugars, acids, polyalcohols, coumarines, psolarenes, and phenolics content to find out the best classes of compounds for further investigations on quality control as well as regulatory assessments. MATERIALS AND METHODS Chemicals. Standards of volatile compounds, coumarins, phenolics, carbohydrates, polyalcohols, and acids were purchased from commercial * To whom correspondence should be addressed: Tel.: +39-0522- 522023. Fax: +39-0522-522059. E-mail: andrea.antonelli@unimo.it. ² Universita ` di Bologna. ‡ Universita ` di Reggio Calabria. § Universita ` di Reggio Emilia. 4978 J. Agric. Food Chem. 2003, 51, 4978-4983 10.1021/jf030083d CCC: $25.00 © 2003 American Chemical Society Published on Web 07/12/2003