Forecasting the Vicinal Diketone Content of Finished Beer. Takashi Inoue, Kirin Brewery Co., Ltd., Takasaki, Gumma Pref., 370-12, Japan. J. Am. Soc. Brew. Chem. 36:0009, 1978.

Studies were made to calculate the total concentration of acetohydroxy acids (AHA) plus vicinal diketones (VDK) in filtered beer at an early stage of lagering. Concentration of AHA decreased during lagering according to first-order kinetics in which the velocity constant was virtually a function of temperature. Concentration of VDK was determined by integrating the difference in the rates of the following two reactions: 1. Its stoichiometric formation from AHA and; 2. Its absorption by yeasts. Concentration of VDK remained virtually constant from the time, after several days of lagering, when the concentration of yeast cells began to decrease according to first-order kinetics. According to these results, the total concentration of AHA + VDK in filtered beer could be calculated at an early stage of lagering from the concentrations of AHA + VDK and the yeast cells at the day of calculation and the predetermined temperature program.

Keywords: Calculation, Diacetyl, Lagering, Yeast concentration.