A dash of gunflint to boost aroma in white wines

Friday May 29 2020 by Vitisphere

 Galdric Nogues, product manager for Lamothe Abiet's fermentation range, monitored the research in conjunction with the Asti viticulture and oenology research centre in Italy during the 2019 harvest. Galdric Nogues, product manager for Lamothe Abiet's fermentation range, monitored the research in conjunction with the Asti viticulture and oenology research centre in Italy during the 2019 harvest. - Photo credit : Cédric Faimali/GFA

Initially, our aim was to better characterise expression of our two thiol-revealing flagship yeasts in the Excellence range, TXL and FTH, in an aromatic Italian grape variety”, explains Galdric Nogues, product manager of Lamothe Abiet's fermentation range. And that grape variety is Cortese. It produces white wines, both still and sparkling, that are rich in thiols mainly in Veneto and Piedmont. Both yeasts were used to ferment the same freshly pressed Cortese must. Then Lamothe-Abiet measured the resulting thiols in the wines. But there was a problem.

The two yeasts produced the three main known thiols at about the same concentration: about 2,000 ng/L of 3MH, between 20 and 35 ng/L for 3MHA and 5 ng/L for 4MMP”, announces Nogues. And yet the wines were very different. The TXL produced a rounded white wine with strong tropical fruit characters, whilst the FTH yielded intense notes of boxwood accompanied by tropical aromas and, above all, marked minerality.

After further measurements, Lamothe Abiet discovered the explanation - in this case a thiol that had never been detected before in wines fermented with FTH: BMT or benzenemethanethiol. Characterised at the start of the 2010s, the thiol displays mineral aromas of gunflint. It has recently been measured by specialist laboratories. Its detection threshold in the wine is very low (0.3 ng/L) compared to classic thiols (from 0.8 to 60 ng/L).

We measured it at 3.5 ng/L, which is a significant amount!” explains Nogues. “Now that we know that FTH produces BMT, we are going to study the impact of the grape variety and different winemaking practices, such as cold stabilisation of the deposit from the must”.

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