Balsamic vinegar is one of the best known and most popular types of vinegar, and it is a rich source of polyphenolic compounds. The quality of balsamic vinegar as well as the content of phenolic substances vary depending on the production method. In the present work, we have developed a method for comprehensive characterization of the content of phenolic compounds in balsamic vinegars based on the combination of gas chromatography (GC) and high-performance liquid chromatography (HPLC) coupled with mass spectrometric detection in single mode (MS) and tandem mode (MS/MS). In total, 14 samples of different types of balsamic vinegar were analyzed without difficulty in sample preparation. The separation conditions and detection parameters of HPLC-MS/MS were optimized and used for the determination of 29 phenolic compounds and 6 phenolic acids. The profile of phenolic compounds was completed by semi-quantitative analysis of volatile organic compounds using GC-MS after optimized headspace solid-phase microextraction. Gallic acid, protocatechuic acid, caffeic acid, and p-coumaric acid have been identified as the major phenolic compounds in balsamic vinegars.

Vinegars are natural products manufactured by two-step fermentation. One of the most famous is balsamic vinegar, especially that produced in Modena, Italy. Its unique production process positively distinguishes it from other vinegars. There are basically three types of balsamic vinegar: common balsamic vinegar, Balsamic vinegar of Modena, and Traditional balsamic vinegar of Modena. The chemical analysis of these vinegars is mainly carried out by using gas or liquid chromatography, often coupled to mass spectrometric detection. Although gas chromatography is generally used for the determination of the overall profile of volatile organic compounds, furfurals, phenolic compounds, and organic acids, high-performance liquid chromatography is typically applied for the determination of amino acids, sugars, and polyphenols. The two complementary techniques, the combination of which is useful for the detailed characterization of balsamic vinegars, are reviewed and discussed in this article.