Czech J. Food Sci., 2009, 27(4):267-275 | DOI: 10.17221/128/2009-CJFS

Optimisation of lab-scale continuous alcohol-free beer production

Radek Lehnert¹, Pavel Novák¹, Filipe Macieira², Michal Kuřec¹, José A. Teixeira², Tomáš Brányik¹

¹ Department of Fermentation Chemistry and Bioengineering, Faculty of Food and Biochemical Technology, Institute of Chemical Technology, Prague, Czech Republic

² Centro de Engenharia Biológica, Universidade do Minho, Braga, Portugal

In order to study the formation and conversion of the most important flavour compounds, the real wort used in alcohol-free beer fermentation was mimicked by a complex model medium containing glucose, yeast extract, and selected aldehydes. The fermentation experiments were carried out in a continuously operating gas-lift reactor with brewing yeast immobilised on spent grains (brewing by-product). During the continuous experiment, parameters such as oxygen supply, residence time (Rt), and temperature (T) were varied to find the optimal conditions for the alcohol-free beer production. The formation of ethanol, higher alcohols (HA), esters (ES), as well as the reduction of aldehydes and consumption of glucose were observed. The results suggest that the process parameters represent a powerful tool in controlling the degree of fermentation and flavour formation brought about by immobilised biocatalyst. Subsequently, the optimised process parameters were used to produce real alcohol-free beer during continuous fermentation. The final product was compared with batch fermented alcohol-free beers using the methods of instrumental and sensorial analysis.

Keywords: alcohol-free beer; continuous reactor; immobilised yeast; beer flavour

Published: August 31, 2009  Show citation