Phenolic composition and quality of white d.o.c. wines from Marche (Italy)

Two white d.o.c. wines produced with grape varieties typical from the region of Marche (Italy) were subjected to high performance liquid chromatography coupled with electrospray tandem mass spectrometry in order to characterize the phenolic fraction. Unlike Verdicchio, Passerina showed relatively high concentrations of tyrosol (up to 45 mg L−1) and quercetin, with the glucuronide (20 mg L−1), being more concentrated with respect to the free form (6 mg L−1). Conversely, Verdicchio showed high concentration of 3,4-dihydroxyphenylethanol (hydroxytyrosol) and hydroxycinnamic acids, such as caffeic, caftaric, coumaric and 2-S-glutathionylcaftaric acid and remarkable amounts of their esters with ethanol (total amount in the order of 30 mg L−1). The different composition of the phenolic fraction had a strong impact on the sensory properties, as confirmed by the sensory data elaborated with principal component analysis (PCA): the taste of burning and astringent was associated with caftaric, ethyl coumarate and 2-S-glutathionylcaftaric acid (thus with Verdicchio), whereas the taste of honey, fruity and exotic fruits was related to Passerina. The identification of 2-S-glutathionylcaftaric acid was performed with HPLC coupled with tandem mass spectrometry in the positive and negative electrospray ionization mode and is discussed here.