Teapots, fluid dynamics, and baked potatoes – but what are we to do with the buttery taste?

Beating the teapot effect

(Submitted on 17 Oct 2009)

Cyrill Duez’s team show that superhydrophobic surfaces stop the tea from wetting the inner surface of the spout and pretty much stop the dripping.

Richard Alleyne, science correspondent for the UK Telegraph newspaper, says this backs up the old adage that putting butter inside the spout stops the drip.

But no-one is saying what we should do with the buttery taste – maybe get used to it like the Tibetans have with tsampa (toasted barley flour, green tea, and yak butter) – see picture on the last page of the linked PDF file

Of course all this leads to some interesting side trips on the internet, this time to the web page of Lydéric Bocquet an the Liquids @ interfaces’ group at the Laboratoire de Physique de la Matière Condensée et Nanostructures, Université Lyon 1, and a link to a paper of his from The American Journal of Physics from 2007 called “Tasting edge effects“. The paper  backs a hypothesis that, to quote him, “the baking of potato wedges constitutes a crunchy example of edge effects” .  He goes on to say in the abstract- “A simple model of the diffusive transport of water vapor around the potato wedges shows that the water vapor flux diverges at the sharp edges… This increased evaporation at the edges leads to the crispy taste of these parts of the potatoes“.

All I can say is, thank goodness this happens and that baked potatoes have extra tasty edges, all a function of increased drying rates that speed Maillard browning.

FotoosVanRobin via Flickr

Coffee stains explained

And an hour later  – even more interesting things – like the paper 12 years ago in “Nature” that explained the nature [pardon the unintentional but awful pun]  of the rings in coffee stains via a flow from the interior of the liquid to the exterior, bringing suspended material with the flow and depositing it at the edge of the drying droplet. And coffee is a good example because oft he amount of dispersed but not dissolved material in the cup. It would be interesting to see if the effect is more pronounced with espresso than drip filter given the far higher level of suspended solids in an espresso cup.

Capillary flow as the cause of ring stains from dried liquid drops“  Robert D. Deegan et al

Nature 389, 827-829 (23 October 1997) | doi:10.1038/39827 – even folks without a full text subscription should be able to access the abstract via this link .

Who’da thought Nature would be interested in coffee stains – still,  the journos and editors, they probably live on coffee.

Engaging students from the get-go

Starting a class today – Food Polymer Science for graduate students.

Getting students engaged is a challenge – even at this level (MS & PhD candidates) – some of them are only doing the course for required credits. So what can we do?

Mano Singham in Liberal Education** rails against the traditional “rule-infested, punitive, controlling syllabus that is handed out to students on the first day of class“, claiming that what is missing is any mention of learning and any indication of the passion of the instructor for the subject matter [we hope the instructor has some passion]. Our formal syllabi here at Oregon State U do list anticipated learning outcomes, but what is missing is the first person-narrative of the instructors view of the subject in the context of food production, consumption, and we hope, the enjoyment of our food.

The Center for Teaching and Learning here at OSU has a summer workshop on a “living course” – a guide to creating a partially web 2.0 based class delivery mechanism. A key part of the development of a living course/syllabus was to create a first person course narrative as a welcome to students and as a way of bringing the subject to life from the start.

I have linked to the current course narratives for both the graduate food polymers course as well as my science of deliciousness course for any of you food science instructors out there who are interested. Comments are welcome.



**Via TEACHING TIPS from the University of Hawaii’s Honolulu Community College.

Rye bread baked from a formula in Michel Suas’ “Advanced Bread and Pastry – A Professional Approach” from the San Francisco Baking Institute.