Method for the Simultaneous Assay of Diacetyl and Acetoin in the Presence of alpha-Acetolactate: Application in Determining the Kinetic Parameters for the Decomposition of alpha-Acetolactate

摘要

A simultaneous assay method for diacetyl and acetoin was developed to investigate the formation of diacetyl during the brewing of alcoholic beverages.A GC-MS analysis after the extraction from neutralized sample by ethyl acetate gave accurate assay results.The detection limit was below 0.1 mg/l and the assay was quantitative from 0.1 to 100 mg/l for both compounds.Unlike other methods,the assay results were unaffected by the presence of alpha-acetolactate (up to 26 mg/l),which easily decomposes to diacetyl or acetoin,because the extraction condition prevents the decomposition and extraction of this acidic compound.Since our assay is compatible with samples that contain a-acetolactate,the kinetic parameters for decomposition of alpha-acetolactate to diacetyl and acetoin were determined.The decomposition rate constants were affected by the ethanol concentration.Overall kinetics for the decomposition of alpha-acetolactate was formulated as a function of ethanol concentration,pH and temperature.The kinetics can be applied to alcoholic beverages such as sake.