Kvasny Prumysl, 2001 (vol. 47), issue 11-12
Determination of 5-hydroxymethylfurfural (HMF) by means of flow-through analyzer.Peer-reviewed article
J. ŠAVEL, K. PAZOUREK
Kvasny Prum. 2001; 47(11-12): 314-316 | DOI: 10.18832/kp2001022 
The article deals with the determination of 5-hydroxymethylfurfural in intermediates and beer during its production and storage by means of SKALAR flow-through analyzer. The determination is based on the classic Winkler's method with barbituric acid and p-toluidine after precious separation of HMF in a dialyzer unit. In the work, HMF contens were monitored in laboratory wort, hopped wort, hopped wort under fermentation and ready bottled beer in the course of its aging. The content of HMF in bottled beer was increasing in course of storage, this was also dependent on the type of beer. The changes in HMF content that were found were in agreement with...
Determination of vicinal diketons in beer by means of SPME method.Peer-reviewed article
T. HORÁK, J. ČULÍK, P. ČEJKA, M. JURKOVÁ, V. KELLNER
Kvasny Prum. 2001; 47(11-12): 316-321 | DOI: 10.18832/kp2001023
The necessity of monitoring of the content of vicinal diketons - 2,3-butandione (diacetyl) and 2,3-pentanedione - in beer is based on the fact that the exceeding of threshold concentration of perception results in the negative influence of sensorial properties of beer, called as butter aroma. For the determination of these substances, a spectrophotometry method is used after distillation with water stream, high-efficient liquid chromatography or gas chromatography in connection with headspace technique. This work gives a new opportunity of the selective determination of diacetyl and pentanedione by means of gas chromatography. During the preparation...
Development of colloidal hazes in bottled pale lager beer during ageing.Peer-reviewed article
P. SLADKÝ, H. CÍSAŘOVÁ, M. DIENSTBIER, P. GABRIEL
Kvasny Prum. 2001; 47(11-12): 322-327 | DOI: 10.18832/kp2001024
The haze development patterns of protein - polyphenol beer colloids has been simultaneously studied at nephelometric 90° angle and forward 15° angle of scattered light, directly an intact commercially bottled 12 grade pale lager beer samples at various thermal ageing conditions. It has been discovered and proved that during the beer ageing process the size of protein - polyphenol chill haze particles is temporary growing over the one micrometer dimension and dissolves again with increasing ageing tome as indicated by the appearance of temporary forward scattering haze maximum on the haze development pattern curve. The observed effect can be explained...