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For optimal expression of varietal thiols

Thiols in wine, what do we talk about?

The thiols are:

scissors

Present in the grapes as odorless precursors
(bound to glutathione and cystein)

scissors

Revealed by the yeast through enzymatic action during alcoholic fermentation

scissors

The β-lyase is the enzyme related to the release of volatile thiols, from odorless thiol precursors

There are 3 main volatile thiols:

plant

4MMP

grapefruit

3MH

fruit

3MH-A

Are all yeasts equal in their ability to reveal thiols?

There is a wide variability between yeast strains, due to their intrinsic beta-lyase activity modulated by the IRC7 gene expression.

Aroma
precursor Béta-Lyase scissors green

Thiols
Realase
of aromas

IRC7 dnk

IRC7 gene (like every gene) possesses 2 alleles which exist in two versions:

LONG FORM IRC7L

Higher

beta-lyase expression

colba colba

IRC7L
Long

colba2 colba2

IRC7L
Long

SHORT FORM IRC7S

Not fully

functional beta-lyase

colba colba

IRC7S
Short

colba2 colba2

IRC7L
Long

Fleche

Only 17% of all yeasts have double alleles in their long form (IRC7L)

And there are also 2 different versions of IRC7 whatever the allele length (short or long): an original version and an altered one.

Fleche green

Only 20% of wine yeasts have the ORIGINAL version of IRC7

Original

schema-1
Original
altered

Up to 80% less thiol release compared to original version

Altered

schema-2
altered

Up to 80% less thiol release compared to original version

Only 3% of all wine yeasts own both features

And only one is
commercially available:

Product
Graphe

Control SauvyTM

Graphe

Thiols released by SAUVY™ (3MH + 3MH-A + 4MMP) compared to a reference thiolic yeast (average of 7 trials performed in Sauvignon blanc from France, Germany, United States, New Zealand and Chile)

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Sauvy - LP
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