METHYL SALICYLATE, A COMPOUND INVOLVED IN BORDEAUX RED WINES PRODUCED WITHOUT SULFITES ADDITION
Sulfur dioxide (SO₂) is the most commonly used additive during winemaking to protect wine from oxidation and from microorganisms. Thus, since the 18th century, SO₂ was almost systematically present in wines. Recently, wines produced without any addition of SO₂ during all the winemaking process including bottling became more and more popular for consumers. A recent study dedicated to sensory characterization of Bordeaux red wines produced without added SO₂, revealed that such wines were perceived differently from similar wines produced with using SO₂ and were characterized by specific fruity aromas and coolness1,2. The aim of this study was therefore to progress in wines without added SO₂ specificities characterization, focusing on compounds involved in their particular aroma.
To identify these compounds, a sensory targeted approach using semi-preparative HPLC3 followed by GC-O and GC-MS characterization was applied. For that, the same wines than those used for previous sensory characterization were studied. These wines were produced in 2017 from same merlot grape batches, according to a standard winemaking process, with or without SO₂ addition. First of all, wine aroma extracts were fractionated by semi-preparative HPLC to identify fractions perceived differently between wines. After comparing the fractions of the wines with or without sulfites, three consecutive fractions have been selected for their olfactive difference between the wines. These fractions were then analyzed by GC-O and GC-MS. Methyl salicylate was identified as responsible for sensory differences observed between these fractions. This compound was quantified4 in a large set of commercial red wines. Methyl salicylate was present at higher concentrations in the wines without added SO₂ ranging from 6 to 105 µg/L whereas, in the wines with added SO₂, its concentration was below 10 µg/L. Sensory threshold of methyl salicylate was determined in red wines at 62.3 µg/L and one-quarter of the wines without sulfites studied, presented a concentration higher than this threshold.
Finally, methyl salicylate qualitative sensory impact was characterized in wines without added SO₂ by sensory profile determinations. This was done after a descriptor generation procedure and an adapted training on natural references associated to generated descriptors. This revealed that methyl salicylate was at the origin of wine without added SO₂ coolness and modified fruity aroma perception of these wines.
Issue: OENO Macrowine 2023
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Wines without added sulfites, Methyl salicylate, Sensory analysis, GC-O