|
|
Stanovení koloidní stability u vybraných druhů piv
Petráň, David
Unlike majority of sorts of alcoholic drinks beer is considered significantly un-stable. This thesis examines the factors influencing the stability of beer, especially phys-ical-chemical, primarily content of polyphenols and potential of components of beer to form haze. Twenty eight samples from differently large breweries were processed (Černá Hora, Poutník Pelhřimov, Pegas, Richard and minibrewery of Mendel University in Brno). The total content of polyphenols was determined using the Folin-Ciocalteu method (spectrophotometrically at 750 nm) and subsequently expressed in the content of ferulic acid, which served as a standard for purposes of this study. The average con-tent of polyphenols was in Černá Hora Sklepní 338,5 mg.l-1, in light lager beer Poutník 370 mg.l-1, in light lager beer Pegas 694,5 mg.l-1, in light lager beer Richard 726,3 mg.l-1, in wheat beer from Mendel University in Brno 562 mg.l-1 and in Rauch from Mendel University in Brno 817 mg.l-1. Turbidity of beer for consumption and potential of beer components to form haze using EBC test was also assessed. Both types of turbidity were measured by turbi-dimeter at 620 nm using Helm BaSO4 standard and based on the measured values were compared with the established range of haze. Finally, the results were discussed and assessed physical-chemical stability of observed beers.
|
guest ::
