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Air trapped in pockets of cellulose fiber submerged in stout beer
In this photo of a cellulose fiber submerged in stout beer, pockets of air trapped inside the fiber become seed bubbles that trigger nucleation (the formation of additional bubbles). Here, the initial seed bubble continues to grow larger due to the flux of nitrogen and carbon dioxide (CO2) gas through the walls of the cellulose fibers from the surrounding liquid.
[Research supported in part by the U.S. National Science Foundation.]
Learn more in the Nature article The widget-free way to foamy stout. Date of Image: 2011)
Credit: Michael Devereux, MACSI, University of Limerick, Ireland
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