David Riveros (1), Guy Derdelinckx (1), Almeida Fran (1); (1) KULeuven, Leuven, Belgium
Although primary gushing in beer is not a widespread phenomenon within the global beer industry. The presence of one gushing event in front of a client is bad enough to affect greatly the brand image of a company. Primary gushing is created from the marriage between surface-active molecules, in this case class II hydrophobins, and CO2 present naturally in beer. Due to the amphipatic nature of hydrophobins, these will form elastic monolayers at the gas-liquid interface present at the bottleneck of the beer bottle. The hydrophobic part of this monolayer will adsorb strongly CO2 molecules that, by the movement of the bottle during the process, will be trapped and stabilized in the shape of a nanobubble. These nanobubbles of about 100 nm at atmospheric pressure will shrink to about 60-70 nm at 4 bar, remaining stable until the opening of the bottle, when sudden expansion of the bubble will break them, releasing enough energy to induce nucleation and strong overfoaming. The detection of 100 nm nanobubbles has been done already by dynamic light scattering (DLS); however, the detection of stabilized CO2 nanobubbles inside the bottle at 4 bar had remained elusive until now. In an effort to solve this problem we used a pressured DLS, as well as known experimental conditions of the sample, such as CO2 concentration, opening temperature and hydrophobin concentration. After this, the detection of 60-70 nm nanobubbles has been solved with reproducible results. These exciting finding are not just the experimental proof of nanobomb theory, but an additional step to include the DLS method of detection for primary gushing in beer.
David Riveros received a B.S. degree in microbiology from Pontificia Universidad Javeriana in Colombia. Later on, in 2008, he obtained his master’s degree in Valdivia (Chile). He is now pursuing his doctoral studies at Katholieke Universiteit Leuven in Leuven, Belgium, under the supervision of Prof. Guy Derdelinckx. He is working in a team fully devoted to understanding and controlling primary gushing phenomenon.