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The interfacial surface film that forms on black tea.
The Physics of Black Tea Film
By Dan Bolton
Have you ever noticed a colorful sheen on the surface of your tea? It appears brittle, breaking like ice floes in the arctic as the tea cools. Researchers once thought it formed from waxy substances in leaves released during steeping. That is not the case. The delicate film is an interfacial interaction of air, tea polyphenols, and calcium carbonate ions in water. It does not form on white, yellow, green, or lightly processed oolong teas, only black tea. In many parts of the world soft water prevents the film from forming. Is tea film a fleeting glimmer of color to enjoy or an unsightly scum that dissipates with a squeeze of lemon? Or does it? Caroline Giacomin, a student at ETH Zürich, in Switzerland joins us to explain the physics of tea film from a study she and colleague Peter Fischer recently published in the Physics of Fluids. Read more…
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Rainforest Alliance’s Director for South Asia, Dr. Madhuri Nanda
Regenerative Agriculture: A Holistic Approach
By Dan Bolton
The Rainforest Alliance’s Director for South Asia, Dr. Madhuri Nanda explains that while sustainable farming ensures that agricultural practices do not negatively impact and degrade the environmental, social, and economic aspects of the surrounding ecosystem, the focus shifts in regenerative agriculture towards making the system better by adopting an ecosystem approach to enhance biodiversity and improving soil health through increased microbial activities that build resilient systems capable of withstanding adverse climatic scenarios. Read more…
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