Working Group II. Biopolymers
Head: Prof. Dr. Peter Köhler
This group is working on the characterisation and quantitation of plant biopolymers, in particular those of cereals. The work is focussed on the structural (amino acid sequences, disulphide bonds, other post-translational modifications) and functional (dough properties baking performance, texture) characterisation of the storage proteins of different cereal species. Based on the fact that both the type and the amount of macromolecules may influence the properties of food, an extraction/HPLC method for the quantification of cereal storage proteins has been developed, which is widely used in this group. The techno-functional properties are determined by means of micro-scale methods based on 10 g of flour, which have been developed in our lab and which are highly correlated with the results of standard-scale methods based on 1000 g of flour. This allows correlating compositional data with technologiocal properties and gives insight into mechanisms of action. Another research topic is coeliac disease, which is triggered by the ingestion of storage proteins of wheat, rye, barley, and possibly oats (termed gluten in this context). These storage proteins are incompletely digested in the small intestine and cause damage to the mucosa of coeliacs. The only therapy is a strict life-long omission of gluten. The working group is involved in the elucidation of coeliac toxic amino acid sequences from cereal storage proteins, and also in the development of methods to produce gluten-free food, which is tolerated by patients suffering from coeliac disease.
Future work will be focused on the correlation between techno-functional effects of additives (e.g. emulsifiers and enzymes) and processing (e.g high pressure, thermal and mechanical treatment) and the texture as well as sensory attributes such as mouthfeel. Basic knowledge has been made recently by the work on texture / taste relationships of sodium chloride in wheat bread. Further work on structure and texture is aimed at establishing two-dimensional separation techniques for intact proteins as well as protein hydrolysates. This will provide a more detailed understanding of cereal proteins and other biopolymers. The studies on health effects of cereal proteins will be put onto a broader basis by studying all major intolerances towards cereals (coeliac disease, wheat allergy, Non-Celiac Gluten Sensitivity) and by close collaborations with hospitals. The analytical studies on the quantitation of gluten in (gluten-free) food will be continued. Since appropriate reference proteins are required for this research, the group will be part of international initiatives (Prolamin Working Group, MONIQA Association) aiming at producing reference proteins for gluten analysis. The molecular description of coeliac disease-inducing epitopes of cereal proteins might allow for specific technological treatments to reduce coeliac disease activity through inactivation. This might open up opportunities for internal collaboration with working group III.