The modification of wine aromas and wine texture is an important component of many red and white wines and in base wines of some styles of sparkling wines. Increased mouthfeel and lower acidity are desired characteristics in many wines. All malolactic (ML) starter cultures can give this benefit. The malolactic starter cultures differ in how they affect the aroma of wine. Some may reduce the vegetative aromas more than others. The reduction in the intensity of vegetative aromas will evoke more pronounced fruity (berry) aromas. Some strains of ML bacteria might even help to release fruit/floral/spicy aromas. More study is needed in this area. Starter cultures also differ in the type and amount of buttery, yeasty, nutty, earthy, sweaty aromas they contribute from their metabolism. The winemaker can control the amount of diacetyl contributed by selecting low or high diacetyl producing strains. Excessive amounts of diacetyl found in wine near the end of malolactic fermentation (MLF) can be reduced by leaving the bacteria in contact with the wine longer. This allows them to reduce the diacetyl to acetoin which is not perceptible. A fresh yeast culture can also be added to remove excess diacetyl. Individual ML cultures can leave their flavor imprint on a wine if, following completion of MLF, further microbial growth is inhibited by proper clarification and sulfite additions. If extensive growth of other bacteria (lactic acid bacteria or acetic acid bacteria) and yeast (Brettanomyces or Candida) is permitted then these microorganisms can wipe out all flavor characteristics contributed by the yeast and ML fermentation.
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