Most textured foods are built of a network of small particles and macromolecules held together by a wide range of intermolecular and colloidal forces. Structure, texture and stability are strongly influenced by the strength of these interactions. In addition, texture depends strongly on the history of structural changes during processing. This is particularly the case for particle gel systems containing protein particles and/or protein-coated emulsion droplets.
At our current state of knowledge, we do not understand the mechanisms whereby subtle changes in protein-protein and protein-lipid interactions control the structure and mechanical properties of dairy based textured foods. The objective of this project is to establish definitively these mechanisms though a combined and integrated approach involving computer simulation and a range of powerful experimental techniques.
The strategy is to determine quantitatively the links between interactions, structure and rheology. by interactions it is meant all types of interactions between particles before and after network formation. By structure, it is meant the complete specification of the relative distributions of particles in space. Techniques to be used to determine experimental structure are light microscopy, electron microscopy and image analysis. By rheology we mean the frequency-dependent relationship between stress and strain at small deformations, as well as fracture and deformation-rate dependent behaviour at large deformations.
A key element of the strategy is the use of Brownian dynamics simulation to compute the time-dependent structure and viscoelastic properties of particle gel systems formed from aggregating particles interacting with known interparticle potentials. The timeliness of the project arises from the fact that the technique of computer simulation of aggregation and gelation in concentrated colloidal systems has reached a critical stage of development where it can now be used as a unique diagnostic tool for bridging the knowledge gap between interactions, structure and rheology. The aim is to make a detailed comparison of the evolving structure/rheological properties of real and simulated systems as a way of establishing the relationship between the particle interactions and the macroscopic behaviour of the real model systems. To determine the relationship between composition, processing conditions and gel texture, a link between the particle interactions and the molecular interactions between proteins and lipids at the oil-water interface is needed. This requires detailed consideration of competitive adsorption and interfacial complex formation studied at macroscopic interfaces and in concentrated emulsion systems by a combination of physico-chemical techniques over a range of experimental conditions.
The overall industrial objective is to develop a predictive generic methodology which is powerful enough to improve substantially the ability of manufacturers to create new products of specified and controlled consistency. This means leaping one step beyond our present level of conceptual or descriptive understanding to a much more quantitative level where computer simulation in combination with structural and rheological observations is used as an efficient and reliable tool in new product development. This methodology is necessary if the European food industry is to be able to maintain its competitive edge into the next century.
Funding SchemeCSC - Cost-sharing contracts
KA6 5HL Ayr
114 86 Stockholm
402 29 Göteborg
MK44 1LQ Sharnbrook
6700 EV Wageningen