Caroline Giacomin

Last Name

Giacomin

First Name

Caroline

ORCID

0000-0002-8066-993X

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Publications 1 - 10 of 11

Black tea interfacial rheology and calcium carbonate
Giacomin, Caroline; Fischer, Peter (2022)
Amyloid-Nanocellulose Interactions and Self-Assembly
Kummer, Nico; Giacomin, Caroline; Fischer, Peter; et al. (2022)
Artificial tap water and interfacial rheology of tea varieties
Giacomin, Caroline; Chen, Rebecca Yun; Fischer, Peter (2021)
92nd Annual Meeting of the Society of Rheology: Program and Abstracts
Tap water is known to contain ions including calcium, magnesium, bicarbonate, sodium, sulfate, and chloride. While water has been shown to be important to the turbidity, color, and flavanol content of the brewed tea, most everyday tea drinkers continue to use local tap water. For tea brewed in tap water, an interfacial phenomenon can be observed in a cup of tea. The surface film that forms is brittle and mildly iridescent, it cracks like ice floes when disturbed. Ion content of the water influences the mass of tea film generated such that deionized water forms no collectable film. This ion content, as well as the pH, has been shown to have an effect on the extraction of theaflavin from tea leaves. Additions of common tea add-ins, such as lemon, milk, or sugar have an effect on the physical thickness of the tea film formed but the physical thickness of the film does not correlate directly with the rheological properties of the film [3]. The interfacial film rheological properties are assessed using interfacial rheometry. All films formed in artificial tap water (ATW) exhibit yielding point behavior in interfacial oscillatory shear. Green and black tea are produced from the same plant, Camellia sinensis (L.) and form visible films, while rooibos tea forms no film, visibly or rheologically. Green tea films are less brittle than black tea films. The interfacial moduli of green tea is less affected by ion concentration than black tea. When the effect of milk components is studied, βcaseins extend the yielding interfacial shear strain by one order of magnitude. Β-lactoglobulins reduced the yield point interfacial shear strain. The addition of salt in ion rich ATW brews reduced interfacial viscous and elastic moduli equally by 0.8 Pa m. Conditions forming the weakest film may be useful in producing dried tea mixtures that reduce film appearance in regions with ion-heavy tap water.
Black tea interfacial rheology and calcium carbonate
Giacomin, Caroline; Fischer, Peter (2021)
Physics of Fluids
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.
Amyloid fibril-nanocellulose interactions and self-assembly
Kummer, Nico; Giacomin, Caroline; Fischer, Peter; et al. (2023)
Journal of Colloid and Interface Science
Amyloid fibrils from inexpensive food proteins and nanocellulose are renewable and biodegradable materials with broad ranging applications, such as water purification, bioplastics and biomaterials. To improve the mechanical properties of hybrid amyloid-nanocellulose materials, their colloidal interactions need to be understood and tuned. A combination of turbidity and zeta potential measurements, rheology and atomic force microscopy point to the importance of electrostatic interactions. These interactions lead to entropy-driven polyelectrolyte complexation for positively charged hen egg white lysozyme (HEWL) amyloids with negatively charged nanocellulose. The complexation increased the elasticity of the amyloid network by cross-linking individual fibrils. Scaling laws suggest different contributions to elasticity depending on nanocellulose morphology: cellulose nanocrystals induce amyloid bundling and network formation, while cellulose nanofibrils contribute to a second network. The contribution of the amyloids to the elasticity of the entire network structure is independent of nanocellulose morphology and agrees with theoretical scaling laws. Finally, strong and almost transparent hybrid amyloid-nanocellulose gels were prepared in a slow self-assembly started from repulsive co-dispersions above the isoelectric point of the amyloids, followed by dialysis to decrease the pH and induce amyloid-nanocellulose attraction and cross-linking. In summary, the gained knowledge on colloidal interactions provides an important basis for the design of functional biohybrid materials based on these two biopolymers.
Hagfish mucosa interaction with particles
Giacomin, Caroline; Founta, Dimitra; Vlassopoulos, Dimitris; et al. (2022)
Nanocellulose interactions with different protein aggregates
Kummer, Nico; Giacomin, Caroline; Fischer, Peter; et al. (2022)
Mucosal rheology in fresh and salt waters
Giacomin, Caroline; Founta, Dimitra; Vlassopoulos, Dimitris; et al. (2023)
Tea interfacial rheology
Giacomin, Caroline; Fischer, Peter (2020)
Abstract Book of the 18th International Congress on Rheology (ICR 2020)
Tea is consumed daily worldwide and is present in many culturally significant activities. This includes, among others, British afternoon tea, yerba mate rituals of South America, and traditional tea ceremonies in Japan or China. When tea is left to steep, a thin film at the air-water interface can form. In certain conditions, this film is observable by naked eye and, when disturbed, visibly cracks like sea ice. The properties of this interfacial film are assessed using interfacial shear rheology and surface tension measurements. Layer properties are distinguished between tea varieties and water conditions. Water hardness, acidity, presence of sugar or milk, tea concentration, and brewing temperature all affect the formation of this layer. Interfaces formed in hard water (200 mg/L CaCO3) exhibit increased elastic modulus when compared to those in both moderately hard water (100 mg/L CaCO3) and soft water (0 mg/L CaCO3). All films formed in chemically hardened water exhibit yielding point behavior in an amplitude sweep. Conditions forming strongest layer may be industrially useful in packaged tea beverages for preferable shelf life stability and for milk tea beverages, emulsion stabilization.
Hagfish slime behavior in particle-laden environments
Giacomin, Caroline; Founta, Dimitra; Vlassopoulos, Dimitris; et al. (2022)
Book of Abstracts of the Annual European Rheology Conference (AERC 2022) and the VIII Iberian Meeting on Rheology (IBEREO 2022)

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Caroline Giacomin

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