Studium faktoru senzoricke stability piva

The changes of sensory properties during a beer storage, the so-called staling of beer, represent nowadays one of the main problems in beer research. Present knowledge does not allow full elucidation of this phenomenon and up to date there is no simple technological measure ensuring prolongation of a sensory stability of beer. A heterogeneity of investigated beers and their substantially different features are one of the reasons why technological measure devises for one kind of beer can be proved as utterly ineffective for another beer. Moreover, there are only few research papers dealing with sensory stability of Czech beers. Aldehydes are recognised as the key compounds of beer staling. Therefore, a new method was developed and successfully applied that enables determination of selected aldehydes (namely 3-methyl-butanal, 2-furfural and 2E-nonenal) in beer. Contrary to other procedures, the method does not require an expensive analytical equipment, is not time consuming and provides satisfactory results. An influence of staling on wide range of chemical constituents of beer and its sensory properties during six-month storage of a typical Czech lager at 9C was determined. From analysed compounds, a decrease of total amino acids has been proved with different susceptibility of individual amino acids to the changes. Evaluation of sensory properties showed different tendency of the samples to the changes during storage. A dominant significance of amino acid level in bottled beer and extent of its decrease during storage was established. Beers with original concentration of amino acids less than 800 mg.l-1 showed moderate changes of sensory stability even when the amount of amino acids decreased by 6% in comparison with beers above the limit, with the comparable decrease. In parallel samples stored at room temperature the content of furfuryl alcohol increased for which a mechanism of formation and possible connection with 2-furfural has been proposed and a decrease of ethyl acetate was observed in comparison with fresh samples and samples stored at 9CAvailable from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi