Determination of glycerol carbon stable isotope ratio for the characterization of Italian balsamic vinegars

The gas chromatographic-combustion-isotopic ratio mass spectrometry (GC-C-IRMS) approach was applied to determine the compound-specific 13C/12C isotopic ratio of glycerol in balsamic vinegars of Modena (Italy). In particular, Italian Protected Designation of Origin and Protected Geographical Indication balsamic vinegars, namely the traditionally made Aceto Balsamico Tradizionale di Modena (ABTM) and the industrial Aceto Balsamico di Modena (ABM) products, were analyzed and a first attempt at classification was carried out. The carbon isotopic ratio of the glycerol polyalcohol varies on the basis of origin, varietal or provenance; therefore the discriminating potentiality of this species might be useful to elucidate the balsamic vinegar production process. To do this, a preliminary study was conducted and several marketable products, ABTM and ABM type, were subjected to measurements in addition to samples coming from three ABTM cask series (batteria). Experimental results highlighted the peculiarities of the two different production processes, suggesting the use of the carbon isotopic ratio of glycerol as an additional tool for balsamic vinegar authentication.