Kinetic study of vicinal diketones in brewing (I) formation of total vicinal diketones.

Nakatani, K., Takahashi, T., Nagami, K. and Kumada, J.

Abstract
Considering the fact that VDK gives a strong unmatured flavour to beer, it is essential to know factors effective in its control. The kinetic approach was used to study the influence of wort constituents and fermentation conditions in formation of total VDK during fermentation. Factors involved have been verified and have been used successfully with computer control in plant fermentations to minimize total VDK formation. Results include: (1) max. T-VDK formation is strongly correlated to min. value of FAN reached during fermentation. Their corelation is described by a hyperbolic function; (2) the min. value of FAN is correlated to the FAN content in the starting wort and the amount of yeast growth; (3) the amount of yeast growth is determined by trub content, wort DO, pitching rate, fermentation temperature and CO2 concentration.
Keywords: brewery brewing fermentation free amino nitrogen kinetics vicinal diketones wort yeast