Italian garlic (Allium sativum L.) characterization through gas chromatography-isotope ratio mass spectrometry and headspace gas chromatography-mass spectrometry volatile profile

Italian garlic (Allium sativum L.) is worldwide appreciated for its unique flavour and taste. Excellence varieties such as Aglio di Voghiera and Aglio Bianco di Polesano have been officially recognised by the European Commission through the attribution of the Protected Designation of Origin (PDO) certification mark [1]. On this basis, an effective tool to preserve the reputation and the commercial value of this appreciated product, by assessing its geographical identity, is therefore required. For the first time, a method to analyse 3 volatile compounds that can be found in garlic, namely allyl alcohol (AA), triallyl disulphide (TD) and diallyl sulphide (DD), has been provided. The solid phase microextraction (SPME) followed by gas chromatography-combostiun-isotope ratio mass spectrometry (GC-C-IRMS) successfully lead to the analysis of the carbon isotopic ratios (δ13C) of the mentioned compounds. To ensure the repeatability of the method, a chosen sample has been analysed 10 consecutive times and also in different days. Moreover, the quantification of the volatile compounds was carried out through gas chromatography-mass spectrometry (GC-MS/MS). To first apply both methods, a set made up of 32 red garlic samples coming from 3 different Italian regions (Abruzzo, Lazio and Sicily) has been considered. Higher relative amounts of DD and DT were found in Sicilian samples with respect to Lazio and Abruzzo ones. Although to date no statistical differences could be found among the δ13CAA, δ13CDT and δ13CDD of the three groups, it must be considered the low number of samples, that has to be widened to verify whether the method could make it possible to discriminate among different regions. Moreover, garlic samples belonging to foreign competitors should be considered to look for differences in the δ13C of AA, DT and DD and more volatile compounds could be included in the analysis