Occurrence of methyl salicylate in Lugana wines: aroma impact and biogenesis

AIM: Methyl salicylate (MeSA) has been reported as a potentially impactful compound in Verdicchio wines produced in central Italy. Lugana is another white wine produced in the north-east of Italy from a grape locally known as Trebbiano di Soave, sharing a very similar genetic background with Verdicchio.  The aims of this study were evaluating MeSA occurrence in Lugana, assessing its aroma impact on white wines aroma and elucidating its biogenesis during vinification.

METHODS: Fifteen Lugana wines were analysed for methyl salycilate content in comparison with Verdicchio, Pinot grigio and Garganega wines. MeSA impact on white wine aroma was studied by means of triangular test, adding MeSA at different concentrations. Possible routes of MeSA formation by yeast were investigated by means of a high throughput assay in which S. cerevisiae cells were put in contact with precursor such as salicylic acid (esterification) or glycosidic extracts (glycosidase). Sub-fractions of Lugana glycosidic extracts were also obtained by HPLC fractionation, allowing further evaluation of precursors role. MeSA formation was also followed during fermentation of Lugana must as well as during wine aging. All analyses of  MeSA were carried out by SPME-GC-MS.

RESULTS: MeSA concentration in Lugana wines varied in the range 5-120 g/L, and was on average higher that in the other wines analysed. Sensory data showed that 20 µg/L of MeSA were sufficient to impact wine aroma, conferring floral and balsamic notes. Formation of MeSA was  observed when yeast cells were in the presence of glycosidic extract, whereas esterification of salicylic acid was not confirmed. Release of MeSA from different HPLC fractions was observed, suggesting  multiple possible precursors

CONCLUSIONS: MeSA is present in Lugana wines at concentrations sufficiently high to impact wine aroma. MeSA odor in wine MeSA appears to be associated to floral attributes. MeSA  formation is mostly due to yeast cleavage of grape glycosidic precursor

ACKNOWLEDGMENTS: Biolaffort is acknowledged for financial support.