Entre-deux-Mers AOC

Science serving the mastery of dry white Bordeaux wines Discovering the aromatic character of Sauvignon Blanc.

Sauvignon Blanc aroma is fickle, unstable, strong or too discreet, surprising or disappointing, sometimes tenacious, often fleeting and was a mystery for a very long time. In the ’90s the General oenology team of the Bordeaux Faculty of Oenology directed by Professor Denis Dubourdieu paid particular interest to Sauvignon Blanc. Their research found wine growing and oenology practice leading to the production of quality white wines with good ageing potential for some. Today, this valuable information has spread to wine-making regions all over the world.

Sauvignon Blanc wines have different aroma profiles to those using other grape varieties. The volatile thiol molecules which give Sauvignon Blanc its distinctive aroma are:

• 4-mercapto-4 methyl-pentan-2 one

(4MMP) strong flavour of boxwood and broom • 3-mercapto-1-hexanol-ol (A3MH) with a complex boxwood and passion fruit nose

• 4-mercapto-4 methyl-pentan-2 ol

(4MMPOH) lemon zest nose • 3-mercaptohexan-1ol (3MH) hints of grapefruit and passion fruit

These thiols have a great impact on the aroma of Sauvignon Blanc wines; their perception threshold is very low. Present in the grapes in the form of odourless precursors they are released due to yeast action during alcoholic fermentation. Professor Denis Dubourdieu’s team has highlighted vine and winery practice for reaching aromatic potential: • moderate water stress approximately four weeks before harvesting helps aroma precursor compound synthesis; • controlled nitrogen nutrition helps aroma precursor compound synthesis and diminishes phenolic compound levels; • moderate water deficit while ripening and no deficiencies in but not excessive nitrogen nutrition gives very typical tasting Sauvignon Blanc wines.

Factors which influence alcoholic fermentation will affect revealing aromas and therefore the final product: the nutrients available for yeast development, the choice of yeast strain, fermentation temperature, quantity of oxygen, the choice of ageing means (using tanks or barrels), ageing duration, stirring – to agitate the lees (the frequency and duration of), the type of cork (regular, synthetic, screw cap), etc.

Crispness, a trade secret

Very early morning harvesting

• Ensuring the vineyard’s perfect state of health. • Adapting the date for optimum harvesting according to the variety. • Transporting the harvest quickly and gently • Controlled yields

In Bordeaux, harvesting always begins with the white varieties destined to produce dry white wines (from the end of August, very beginning of September).

Grapes being in a perfect state of health is essential for producing these wines. Any weathered grapes notably increase the wine’s susceptibility to oxidation.

Harvesting date is an important and sensitive stage. Bordeaux wines are the fruit of assembling several grape varieties and parcels. The harvesting date must therefore take the sugar level, phenolic and aromatic ripeness of each variety into account. Too early, it gives wines with dominant herbal aromas, too late it gives wines which are not refreshing and with very little aroma.

Harvesting takes place at sunrise in order to preserve the morning crispness and so that the heat doesn’t alter the grapes. Harvesting can be either manual or mechanical.