Black tea interfacial rheology and calcium carbonate
An interfacial phenomenon can be observed in the kitchen in a cup of black tea. When tea is left to cool after steeping, a thin film at the air-water interface can form. In certain conditions, this film is observable by naked eye and, when disturbed, cracks visibly like sea ice. The mechanical prope...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/505412 2023-05-15T18:18:34+02:00 Black tea interfacial rheology and calcium carbonate Giacomin, Caroline Fischer, Peter 2021-09 application/application/pdf https://hdl.handle.net/20.500.11850/505412 https://doi.org/10.3929/ethz-b-000505412 en eng AIP Publishing info:eu-repo/semantics/altIdentifier/doi/10.1063/5.0059760 info:eu-repo/semantics/altIdentifier/wos/000749832400004 http://hdl.handle.net/20.500.11850/505412 doi:10.3929/ethz-b-000505412 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International CC-BY Physics of Fluids, 33 (9) info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2021 ftethz https://doi.org/20.500.11850/505412 https://doi.org/10.3929/ethz-b-000505412 https://doi.org/10.1063/5.0059760 2022-04-25T14:33:47Z An interfacial phenomenon can be observed in the kitchen in a cup of black tea. When tea is left to cool after steeping, a thin film at the air-water interface can form. In certain conditions, this film is observable by naked eye and, when disturbed, cracks visibly like sea ice. The mechanical properties of this interfacial film are assessed using bicone interfacial rheometry. Water hardness, acidity, the presence of sugar or milk, tea concentration, and brewing temperature all affect the formation of this film. Interfaces formed in hard water (200 mg CaCO3/L) exhibit increased elastic modulus vs those in moderately hard water (100 mg CaCO3/L), soft water (50 mg CaCO3/L), and Milli-Q water. All films formed in chemically hardened water exhibit yielding point behavior in the interfacial oscillatory shear. Film physical thickness shows no correlation with measured physical strength. Conditions forming the strongest film, chemically hardened water, may be industrially useful in packaged tea beverages for preferable shelf stability and for emulsion stabilization of milk tea products. Conditions forming weakened films, addition of citric acid, may be useful for dried tea mixes. In lab conditions, the film visibility is obscured due to purity of tea ingredients and careful washing. However, the film physically forms and can still be measured through interfacial rheometry. ISSN:1070-6631 ISSN:1089-7666 ISSN:0031-9171 Article in Journal/Newspaper Sea ice ETH Zürich Research Collection |
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ETH Zürich Research Collection |
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language |
English |
description |
An interfacial phenomenon can be observed in the kitchen in a cup of black tea. When tea is left to cool after steeping, a thin film at the air-water interface can form. In certain conditions, this film is observable by naked eye and, when disturbed, cracks visibly like sea ice. The mechanical properties of this interfacial film are assessed using bicone interfacial rheometry. Water hardness, acidity, the presence of sugar or milk, tea concentration, and brewing temperature all affect the formation of this film. Interfaces formed in hard water (200 mg CaCO3/L) exhibit increased elastic modulus vs those in moderately hard water (100 mg CaCO3/L), soft water (50 mg CaCO3/L), and Milli-Q water. All films formed in chemically hardened water exhibit yielding point behavior in the interfacial oscillatory shear. Film physical thickness shows no correlation with measured physical strength. Conditions forming the strongest film, chemically hardened water, may be industrially useful in packaged tea beverages for preferable shelf stability and for emulsion stabilization of milk tea products. Conditions forming weakened films, addition of citric acid, may be useful for dried tea mixes. In lab conditions, the film visibility is obscured due to purity of tea ingredients and careful washing. However, the film physically forms and can still be measured through interfacial rheometry. ISSN:1070-6631 ISSN:1089-7666 ISSN:0031-9171 |
format |
Article in Journal/Newspaper |
author |
Giacomin, Caroline Fischer, Peter |
spellingShingle |
Giacomin, Caroline Fischer, Peter Black tea interfacial rheology and calcium carbonate |
author_facet |
Giacomin, Caroline Fischer, Peter |
author_sort |
Giacomin, Caroline |
title |
Black tea interfacial rheology and calcium carbonate |
title_short |
Black tea interfacial rheology and calcium carbonate |
title_full |
Black tea interfacial rheology and calcium carbonate |
title_fullStr |
Black tea interfacial rheology and calcium carbonate |
title_full_unstemmed |
Black tea interfacial rheology and calcium carbonate |
title_sort |
black tea interfacial rheology and calcium carbonate |
publisher |
AIP Publishing |
publishDate |
2021 |
url |
https://hdl.handle.net/20.500.11850/505412 https://doi.org/10.3929/ethz-b-000505412 |
genre |
Sea ice |
genre_facet |
Sea ice |
op_source |
Physics of Fluids, 33 (9) |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1063/5.0059760 info:eu-repo/semantics/altIdentifier/wos/000749832400004 http://hdl.handle.net/20.500.11850/505412 doi:10.3929/ethz-b-000505412 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/20.500.11850/505412 https://doi.org/10.3929/ethz-b-000505412 https://doi.org/10.1063/5.0059760 |
_version_ |
1766195187300696064 |