The aroma of butter having the name of diacetyl!
What is the diacetyl taste? It’s butterscotch-like, a hard yellowish-brown sweet made from butter and brown sugar.
Diacetyl is a volatile compound so-called vicinal diketone (VDK) because it has two C=O groups, side-by-side. Its buttery character plays an important role in beers giving them a typical flavour.
So Diacetyl and VDKs have an effect on the organoleptic profile of the finished beer.
Yeast and VDKs
VDKs are some products of yeast metabolism and they are formed in every brewery fermentation.
The amount of diacetyl produced is yeast strain-dependent but wort composition and fermentation conditions, as well as temperature, are also significant parameters to overall diacetyl levels.
The effects of diacetyl and other VDKs on the organoleptic profile
Diacetyl concentrations above 0,05 mg/L can be perceived as a negative flavour characteristic in some “lager” (a type of beer conditioned at low temperature), while concentrations about 1 mg/L are allowed in “ALE” (a type of beer brewed using a warm fermentation method), in order to balance the peculiar full-bodied and fruity taste of ale beers.
The determination of VDKs
Performing the analysis for the determination of VDKs is essential to achieve an improvement in the production process, management and finally the conservation of the product.
Check out the key points about Diacetyl and VDKs in brewing process
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