cfaed Seminar Series
Prof. Dr. Thomas A. Vilgis, Dr. Birgitta Zielbauer , Max Planck Institute for Polymer Research, Mainz, Germany
Pre-Christmas bakery: delicious soft and hard matter physics
, 13:00 - 14:00
TU Dresden, Max Bergmann Zentrum (MBZ), Seminar Room Bio, , Budapester Str. 27 , 01069 Dresden
No matter in which culture, great religious feasts lead to opulent sweets and high level bakery art work resulting in cakes, cookies and other sweet delicious confectioneries. Star shaped cinnamon biscuits (Zimtsterne, “cinnamon stars”), Panettone in Italy, Stollen in Dresden, sugar pretzels and other examples define a class of sugar based foods with exceptional sweet taste, but very different mouth feel. In this talk the different “universality” classes of bakery products will be considered from a simple physical point of view.
Proteins, water, starch and granular materials, such as ground nuts and almonds, form different kinds of dough, based on simple molecular properties. Wheat flour and water form viscoelastic elastic dough materials which can be widely deformed without rupture. Short bread and cookies based on granular materials form brittle semi-solid doughs.
The role of the sugar, apart from its culinary function as sweetener, is essential for the physics of the different systems. In panettone and other sponge mixtures (Biskuit in German) it binds water and keeps moisture during baking and longtime storage. In short bread and cinnamon stars it forms together with proteins (wheat or egg white) glasses after drying (“baking”) between the granules.
The central message of the talk will be a unified view of the dough based on the different functions of its basic ingredients proteins, starch, water and fat, where sugars provide fine tuning on local scales – especially in Christmas bakery.
Thomas Vilgis studied physics at the University of Ulm, where he also received his PhD in physics. He spent his postdoc time at the Cavendish Laboratory at Cambridge, UK. In 1990 he obtained his venia legendi from the University of Mainz and spent two years as directeur de recherche at the Institute Charles Sadron in Strasbourg. His main activities at the Max-Planck-Institute for Polymer Research, Mainz, have been the field of statistical mechanics of polymers and soft matter. Since five years Vilgis leads also an experimental ‘soft matter food science’ group at the same institute.
Birgitta Zielbauer, born in 1978, studied Physics at Heidelberg University, where she received her doctor’s degree in Nanotechnology in 2007. After 2 years of research in France, she started working as scientific assistent and became part of Prof. Thomas Vilgis workgroup „Soft Matter and Food Science“ at Max-Planck-Institute for Polymer Research in Mainz. There she is researching the physical properties and the physical structure of food.