DLLME AND GAS CHROMATOGRAPHY ACCURATE MASS SPECTROMETRY PROFILING OF AROMA COMPOUNDS IN GRAPE MARC DISTILLATES

FONTANA, A.; CELA, R.; RODRIGUEZ, I.

Santiago de Compostela

Conferencia; 40th International Conference on Environmental & Food Monitoring; 2018

Facultad de Química, Universidad de Santiago de Compostela

Grappa contains hundreds of volatile and semi-volatile species, either coming from seeds and peels of grape marc, or generated during the fermentation of the pomace [1]. These compounds are responsible for the organoleptic properties, and thus the quality, of these spirits. In addition, they serve as markers of grape variety, geographic origin, storage conditions of grape pomace and /or distillation techniques [2].In this presentation, the suitability of the DLLME sample preparation technique, followed by GC-TOF-MS analysis, for the profiling of volatile and semi-volatile organic compounds in grappa distillate samples is assessed. DLLME conditions are optimized using a selection of aroma compounds from different chemical families. The efficiency of the final extraction procedure is compared to that obtained using other techniques, such as SPME. Thereafter, identification of major and minor compounds in the DLLME GC-TOF-MS records is performed. A preliminary evaluation of chromatographic profiles to discriminate different distillates by using the molecular features extracted from GC-EI-TOF-MS chromatograms is shown.Identities of more than 100 aroma compounds is proposed from their accurate fingerprints EI-TOF-MS spectra, in combination with literature data of their linear retention index. The mined analytes belong to the main classes of aroma compounds in distillates: carboxylic acids and their esters with alcohols, acetals, aldehydes, ketones, benzene derivatives and terpenes. Tentative identities for some compounds are confirmed with authentic standards, whose accurate spectra are incorporated in a customized accurate database. The usefulness of responses for deconvoluted aroma compounds to discriminate distillates obtained from different grape marc varieties is illustrated with principal component analysis plots.