Diacetyl

Diacetyl is a compound formed during malolactic fermentation. This ‘fermentation’  (bacterial action actually) reduces the acidity of wine and gives nutty and caramel flavours to the wine. A lot of wines undergo malo but sometimes the level of diacetyl is too high and it can actually spoil the wine imparting intense buttery flavours. I am coming across this more frequently in Chablis these days. The buttery flavour actually masks the primary fruit flavours of the wine. When faced with high natural acidity  some producers fear that the consumer will not enjoy these wines therefore they reduce the acidity with malo and sometimes to the detriment of the wine. Chablis is meant to have high acidity as this is part of its style and profile. Unfortunately this is just another case of wine being dumbed down for the consumer and ruined for the amateur.