Effect of tunnel pasteurization upon sensory stability of beer. II. Monitoring of effect given by time of pasteurization carried out at the temperature of 63 °C.

This information follows up withthe previous article (Kvasny Prum. 47, 2001, p. 202)and presents results of the influence upona wide spectrum of the physicochemical parameters of beer, given by the effect of the time of tunnel pasteurization realized on full scale produced pale lager beers at the temperature of 63 °C. The prolongation of the pasteurization period became evident by increase of colours and contect of diacetyl and oxidized polyphenols while, contrary to that, total polyphenols, anthokyanogens and bitter substances declined. The samples of beers pasteurized for a longer period had lower reduction capacity and manifested more intense reaction with thiobarbituric acid. The prolonged period of pasteurization reflected as well in the increase of concentration of 3-methylbutanal and 2-furfural, while 2E-nonenal showed ambiguous trend of changes. The content of the total amino acids declined universally with the prolonged pasteurization action whereby, as regards individual amino acids, diverse substantibility for changes was registered. These finding confirm the occurrence of Maillard and oxidation reactions in the tunnel pasteurization. The sensory analysis proved fall of liking for beers with prolonging pasteurization period. The results underline that due attention must be given to the tunnel pasteurization not only from the microbiologie point of view but even because of the sensory stability and the organoleptic properties of beers.(In Czech, English summary only