Home / News / Enartis News – Prevention and Treatment of reductive aromas
 
09 April 2018
 

ENARTIS NEWS – PREVENTION AND TREATMENT OF REDUCTIVE AROMAS

Reduction is one of the most common problems in winemaking. Hydrogen sulphide and other volatile sulphur-containing compounds are generally produced during alcoholic fermentation, but they can also develop during wine storage and ageing, as well as after bottling.

Prevention and treatment of reductive aromas
Reduction is one of the most common problems in winemaking. Hydrogen sulphide and other volatile sulphur-containing compounds are generally produced during alcoholic fermentation, but they can also develop during wine storage and ageing, as well as after bottling. The aromas generated by these sulphur compounds are usually described as rotten egg, burnt rubber, skunky, burnt match, asparagus, onion, and garlic. Additionally, they can impact mouthfeel and intensify other negative wine attributes such as bitterness and herbaceous character. Their presence, when close to or above the sensory threshold, decreases wine aromatic quality. For this reason, it is important to know how to prevent or treat this defect during the different stages of winemaking.

Alcoholic fermentation: the beginning of reduction
Production of sulphur off-aromas begins during alcoholic fermentation.
   • The first mechanism is related to the synthesis of amino acids. Yeast produce hydrogen sulphide as a normal step in the synthesis of sulphur containing amino acids. This explains why accumulation of H2S often occurs in case of deficiency of available nitrogen.
   • A second mechanism is the transformation of the elemental sulphur (S) sprayed in the vineyard to H2S.
   • A third mechanism takes place right after the alcoholic fermentation. The enzymatic activities of the fermenting yeast remain active for at least 10-15 days after the end of the alcoholic fermentation. An addition of SO2 in this phase activates the sulphite reductase activity that turns the toxic compound into the more harmless H2S. This is the reason why, in presence of lees, it is recommended to wait at least two weeks before proceeding with the sulphitation. In the meanwhile, to protect wine form spoiling microorganisms and oxidation, it is possible to use alternatives like Enartis Stab Micro M (antimicrobial preparation of specially activated chitosan) and Enartis Tan SLI (ellagic tannin with strong antioxidant effect extracted from untoasted American oak)

Sulphur compounds responsible of wine reduction
Several different compounds can produce a reductive character in wine: H2S, mercaptans and disulfides are the most known. Not all of them can be removed by copper or aeration. In order to remove offensive sulfur compounds without producing a bigger stink, it’s important to run a simple aroma screen that allows to identify the cause of the problem before deciding the correct curative treatment.

What Treatments are available?
Aeration, copper preparation like Revelarom, tannins like Enartis Tan Elevage are tools that can effectively be sued to solve the problem, depending on its origin.

If you want to know more about the origin of sulphur off-aromas, how to recognise the compounds responsible for this defect and how to prevent and treat it, download the complete newsletter.

 
 

◄ Go Back ▲ Back to top

back to top