Research Laboratory for Beverage Technologies, Research & Development Division, Kirin Co. Ltd., 1-17-1, Namamugi, Tsurumi-ku, Yokohama, Kanagawa, 230-6826, Japan.
Published: April 2019
AI Article Synopsis
Article Abstract
The downward movement of the bubble-texture in a glass of Guinness beer is a fascinating fluid flow driven by the buoyant force of a large number of small-diameter bubbles. This texture motion is a frequently observed phenomenon on pub tables. The physical mechanism of the texture-formation has been discussed previously, but inconsistencies exist between these studies. We performed experiments on the bubble distribution in Guinness poured in an inclined container, and observed how the texture forms. We also report the texture-formation in controllable experiments using particle suspensions with precisely specified diameters and volume-concentrations. Our specific measurement methods based on laser-induced-fluorescence provide details of the spatio-temporal profile of the liquid phase velocity. The hydrodynamic condition for the texture-formation is analogous to the critical point of the roll-wave instability in a fluid film, which can be commonly observed in water films sliding downhill on a rainy day. Here, we identify the critical condition for the texture-formation and conclude that the roll-wave instability of the gravity current is responsible for the texture-formation in a glass of Guinness beer.
Introduction: The global alcohol industry sponsors social/music events targeting young people; however, existing literature focuses on Westernised contexts. Given the decline in young people's drinking in many Western countries, it appears that multinational alcohol companies are importing the strategies they have used in high-income countries to the Global South countries like Nigeria to recoup profits. This study aims to examine the Guinness Show- a free one-month annual music festival, alcohol marketing at the festival and the extent to which the event encourages diverse drinking practices among its attendees.
Beer is made via the fermentation of an aqueous extract predominantly composed of malted barley flavoured with hops. The transforming microorganism is typically a single strain of Saccharomyces cerevisiae, and for the majority of major beer brands the yeast strain is a unique component. The present yeast used to make Guinness stout brewed in Dublin, Ireland, can be traced back to 1903, but its origins are unknown.
Probiotic functionalization of non-dairy beverages has been garnering interest to provide dairy-sensitive populations with greater probiotic product varieties. The addition of probiotics into popularly consumed beverages-carbonated sodas and beers, presents an interesting challenge as the presence of acidic pH, hops-derived compounds, and ethanol have highly deleterious effects. Herein, alginate encapsulation was proposed to improve probiotics viability within sodas and beers.
In a glass of stout beer, a very large number of small dispersed bubbles form a texture motion of a bubble swarm moving downwards. Such a cascading motion is caused by a gravity-driven hydrodynamic instability and depends on the interbubble distance. To estimate these two corresponding indicators, an experimentally measured velocity profile is required and, thus, is obtained a posteriori.
