Kvasný průmysl (Oct 2001)
Effect of amino acids content in beer on its sensoric stability.
Abstract
The additions of amino acids phenylalanin (100mg/l) and methionin (20 mg/l) in the samples of tree types of 12 % pale industrially produced beers, the following artificial aging for 14 days at the temperature of 37 °C and 45 °C, and the natural aging for tree months at the temperature 20 °C have produced no substantial effect on changes in values of colour, polyphenol compounds, vicinal diketones and oxid-reduction capacity when compared with original beers and with the samples with distilled water addition. During the artificial and natural aging, the total content of amino acid has declined. From the point view of sensoric testing, the addition of phenylalanin showed out an inexpressive degradation of the sensoric evaluation results while the addition of methionin proved a considerable one, in particular in the total impression after drink. This implies, in connection with the changes of the amino acid levels, the participation of these compounds in production of undesirable components of the beer old flavour. An expressive degradation of the samples with the added methionin in comparison with the five times higher additions of phenylalanin confirmed different inclination of individual amino acids to degradating changes during the artificial and natural aging of beer and evidently even different intensity of sensoric perception of the resulting products. The degree of the changes dependend on the heat load value. The changes in beer composition, and the degradation of the total impression of beer after drink in course of the sensoric analysis of the sample aged 14 days at the temperature of 37 °C, came near to the changes observed on the same samples that were stored of 3 months at 20 °C. The values of stability tests of TBA number and of the absorptive integrals failed to give comparable results.The additions of amino acids phenylalanin (100mg/l) and methionin (20 mg/l) in the samples of tree types of 12 % pale industrially produced beers, the following artificial aging for 14 days at the temperature of 37 °C and 45 °C, and the natural aging for tree months at the temperature 20 °C have produced no substantial effect on changes in values of colour, polyphenol compounds, vicinal diketones and oxid-reduction capacity when compared with original beers and with the samples with distilled water addition. During the artificial and natural aging, the total content of amino acid has declined. From the point view of sensoric testing, the addition of phenylalanin showed out an inexpressive degradation of the sensoric evaluation results while the addition of methionin proved a considerable one, in particular in the total impression after drink. This implies, in connection with the changes of the amino acid levels, the participation of these compounds in production of undesirable components of the beer old flavour. An expressive degradation of the samples with the added methionin in comparison with the five times higher additions of phenylalanin confirmed different inclination of individual amino acids to degradating changes during the artificial and natural aging of beer and evidently even different intensity of sensoric perception of the resulting products. The degree of the changes dependend on the heat load value. The changes in beer composition, and the degradation of the tota
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