Kvasny Prumysl, 1997 (vol. 43), issue 9
Formation of Aldehydes by Controlled Oxidation of Amino Acids of Beer.Peer-reviewed article
J. ŠAVEL, D. ZDVIHALOVÁ, M. PROKOPOVÁ
Kvasny Prum. 1997; 43(9): 233-236 | DOI: 10.18832/kp1997017 
Amino acids dissolved in distilled water or unhopped wort were oxidized with peroxo (di) sulfate, permanganate and potassium dichromate under a simultaneous steam distillation. During oxidation of amino acids with ammonium peroxo (di) sulfate in water were obtained volatile products with a different nature of off-flavours and a positive reaction with thiobarbituric acid and Schiff s agent and 2, 4 - dinitrophenylhydrazine. Phenylalanine f.e. has provided a floral flavour and methionine a putrefaction of cabbage. During oxidation of amino acids in unhopped wort has only a pungent cardboard flavour arisen and the quantity of volatile substances has decreased....
Utilization of Cryoscopy for Determination of Original Extract of Beer.Peer-reviewed article
P. ČEJKA, M. JURKOVÁ, V. KELLNER, V. MIKAN
Kvasny Prum. 1997; 43(9): 237-238 | DOI: 10.18832/kp1997018
On the collection of 81 beer samples were carried out the determination of original extract of beer by freezing-point method (cryoscopy) on the ADVANCED 3D apparatus from firm Advanced Instruments together with the determination of apparent extract of beer on the A. Paar DMA 55 densitometer. From those two quantities were calculated the alcohol content, real extract and original extract of beer. The obtained results were compared with classical distillation method. A very good congruence between both methods was found. deviation magnitude by alcohol and original alcohol is approximately the same as by the DSA 48 apparatus, by real extract is...