title: Carbon isotope ratios of selected volatiles in Citrus sinensis and in orange-flavoured food.
abstract: BACKGROUND
  Twenty genuine samples of industrially cold-pressed sweet orange essential oils, were analysed by gas chromatography-combustion-isotope ratio mass spectrometry to determine the values of the carbon isotope ratios (δ(13)C(VPDB)) of selected volatiles and assess the corresponding range of authenticity. Successively, four commercial orange-flavoured products were analysed under identical conditions to evaluate the authenticity of the orange flavour. The samples were extracted by solid-phase microextraction under optimised conditions. The evaluation was performed by using an internal standard procedure to neglect the contribution due to the original environment to the isotopic abundance of (13)C. The composition of the volatile fraction of the essential oils and of the flavoured products was determined by gas chromatography coupled to mass spectrometry with linear retention indices, and by gas chromatography with a flame ionisation detector.
  
  
  RESULTS
  The δ(13)C(VPDB) values of seven secondary metabolites determined here were successfully used to characterise genuine orange essential oil. These values were used to evaluate the quality of orange-flavoured products, revealing the presence of compounds of different origin, not compatible with the values of genuine orange secondary metabolites.
  
  
  CONCLUSIONS
  This study provides the range of authenticity of δ(13)C(VPDB) of seven different secondary metabolites in sweet orange genuine essential oil, useful for evaluating the genuineness of orange flavour. In accord with a previous study on different essential oils, the values determined here can be successfully applied for the evaluation of a large number of flavoured food stuffs and correlated with their origins.
authors.affiliation: Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, University of Messina, 98168, Messina, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Schipilliti
authors.affiliation: Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, University of Messina, 98168, Messina, Italy.
authors.forename: Ivana
authors.initials: I
authors.lastname: Bonaccorsi
authors.affiliation: Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, University of Messina, 98168, Messina, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Cotroneo
authors.affiliation: Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, University of Messina, 98168, Messina, Italy.|Centro Integrato di Ricerca (C.I.R.), University Campus Bio-Medico of Rome, Roma, Italy.|Chromaleont s.r.l., A start-up of the University of Messina, c/o Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, University of Messina, Messina, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Dugo
authors.affiliation: Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, University of Messina, 98168, Messina, Italy.|Centro Integrato di Ricerca (C.I.R.), University Campus Bio-Medico of Rome, Roma, Italy.|Chromaleont s.r.l., A start-up of the University of Messina, c/o Dipartimento di Scienze del Farmaco e dei Prodotti per la Salute, University of Messina, Messina, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Mondello
mesh_terms: D002244:Carbon / Q000032:analysis*; D002247:Carbon Isotopes / Q000032:analysis*; D032084:Citrus sinensis / Q000737:chemistry*; D003132:Commerce; D005421:Flavoring Agents / Q000032:analysis*; D005638:Fruit / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D009822:Oils, Volatile / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry; D010938:Plant Oils / Q000032:analysis*; D013649:Taste
chemical_list: D002247:Carbon Isotopes; D005421:Flavoring Agents; D009822:Oils, Volatile; D010936:Plant Extracts; D010938:Plant Oils; D002244:Carbon; C087245:orange oil
keywords: aroma compounds; authenticity; gas chromatography; natural flavour; secondary metabolites; sweet orange