Simultaneous determination of sugars and organic acids in aged vinegars and chemometric data analysis

Aceto Balsamico Tradizionale of Modena (ABTM) is a typical product (PDO denomination) of the province of Modena produced by cooked grape must which undergoes a long ageing period (at least 12 years) in series of wooden casks (batterie). The study of the transformations of this product during ageing is extremely relevant in order to control the authenticity of ABTM towards succedaneous products and mislabelling of age. This paper presents the results of the investigation of sugars and fixed organic acids in ABTM samples of different ages, coming from different batterie. The analytes were simultaneously determined by a gas chromatographic method optimised for this peculiar matrix. The method shows good separation and resolution of the investigated chemical species and allows their determination in the concentration ranges reported in brackets: malic (7.6-15.5 g kg(-1)), tartaric (4.0-9.7 g kg(-1)), citric (0.6-1.5 g kg(-1)) and succinic (0.36-0.62 g kg(-1)) acid and glucose (153-294g kg(-1)), fructose (131-279g kg(-1)), xylose (011-0.39g kg(-1)), ribose (0.078-0.429g kg(-1)), rhamnose (0.061-0.195g kg(-1)), galactose (0.136-0.388g kg(-1)), mannose (0.41-1.46g kg(-1)), arabinose (0.33-1.00g kg(-1)) and sucrose (0.46-6.84g kg(-1)), with mean associated errors ranging from 5 to 19% depending on the analytes. Moreover, the recovery values are always satisfactory, being close to one for most of the analytes. Furthermore, in order to assess the degree of variability of the different analytes content with vinegar ageing and the similarity/dissimilarity among series of casks a three-way data analysis method (Tucker3) is proposed. The chemometric technique applied on the data set shows differences between the samples on the bases of their different ageing period, and between the batterie, which traditionally have an own peculiar production procedure.