Elucidation of the Key Aroma Compounds in Balsamic Vinegars Using Comprehensive Two-Dimensional Gas Chromatography Coupled to Mass Spectrometry.

Traditional balsamic vinegar is one of the best known and most popular types of Italian vinegar in the world. Several factors combine to determine the quality of this product, starting with the grape varieties, the production method used and the geographical area of origin. In the Emilia Romagna region, where the tradition of this product begins, there are two protected designations of origin (PDO) and one protected geographical indication (PGI). The latter are produced exclusively in defined geographical areas (Modena and Reggio-Emilia) and with specific grape varieties grown for that purpose. Traditional PDO balsamic vinegar is made from concentrated cooked must, which is then subjected to a dynamic aging process, that is, in different wooden barrels of decreasing size in which both alcoholic and acetic fermentation take place simultaneously. The aging process lasts for variable lengths of time and ranges from 12 years (affinato) to 25 years (extravecchio). PGI, on the other hand, is given by the combination of cooked wine must with caramel and other thickeners, being a product aimed at broader market needs and therefore sold at a reduced price. In fact, it is produced with a portion of cooked must that is added to wine vinegar and then undergoes aging for up to 3 years in single wooden barrels. The aroma, and thus the characteristic balsamic flavor of this product, is determined by hundreds of volatile compounds that belong to different chemical families. Characterization and understanding of the key aroma compounds present are therefore of great importance in supporting the quality of this food. In this contribution, we exploited multidimensional gas chromatography together with mass spectrometry (GC×GC-MS) to characterize the composition of volatile compounds and associate it with the quality of balsamic vinegar. Separation conditions and detection parameters were optimized for detailed fingerprinting of the aromatic compounds present in order to explain the complexity of the organoleptic profile of these high-value products

Modern sample preparation approaches for small metabolite elucidation to support biomedical research

The analysis of biological samples of clinical interest has certainly many analytical challenges. Among these, the preparation of samples for the determination of metabolites of interest is of paramount importance to avoid error propagation to the following separation/detection steps, but also to simplify the data elaboration. Sample preparation represents the initial key step for the acquisition of reliable and interpretable information. In this review, we showcase and discuss the most recent sample preparation techniques used for biological samples, limiting to those extracting the small (volatile or volatilizable) metabolites, thus those applications which enable the subsequent GC analysis. Essentially, these include the group of sorbent-based and liquid-based sampling techniques. Dedicated sections devoted to both assisted (i.e., ultrasound, microwave) extraction techniques and chemical derivatizations will also be presented. In the discussion, the importance and recent trends towards the development of green solutions in sample preparation, via automation and miniaturization, are highlighted