Research of Physics and Physical Chemistry of Foods
TOPICS
The topics are given in the tables below. The names that are given in the tables resemble that of the group members who have a main interest in the topic(s).
| Scientific challenges at different scales | Food innovations: Product technology (PT), Health (H), Sustainability (S) |
|---|---|
| Physics of complexity and chance phenomena: Dynamics and adaptive processes, delayed creaming/sedimentation, fracture (E. Scholten, P. Venema, E. van der Linden) | Food breakdown versus sensory, sensory-liking, product stability vs. storage and production methods, product-process-properties relations (PT, H, S) |
| Long time dynamics: Aging phenomena, drying, relaxations in concentrated systems (P. Venema) | Edible coatings, powder technologies, reduced water usage in processing, proteins near glass transition (PT, S, FS) |
| Bulk properties versus structure: Visco-elastic / mechanical properties, micro-mechanical properties, swelling / shrinking, influence of external fields, temperature and system composition (P. Venema, E. van der Linden, E. Scholten, G. Sala, L. Sagis, H. de Jongh) | Heat stable high protein drinks for clinical nutrition and infants, high vegetable content pasta’s, texture-taste interactions, food breakdown during mastication, building blocks, reformulation strategies (PT, H, S) |
| Interfacial properties versus structure: Surface visco-elastic / mechanical properties, mass transport through interfaces, effects of external fields, interaction with continuous phase, influence of external fields, and temperature and system composition (G. Sala, L. Sagis) | Heat stable high protein drinks for clinical nutrition and infants, high vegetable content pasta’s, texture-taste interactions, food breakdown during mastication, building blocks, reformulation strategies (PT, H, S) |
| Structural (self-) organisation of complex systems: Kinetics and thermodynamics, network morphology, phase behaviour (P. Venema, E. van der Linden, E. Scholten, G. Sala, L. Sagis, H. de Jongh) | High concentrated protein systems, meat replacers, reformulations using plant proteins, texture-taste interactions, fibers by electro-spinning, double emulsions, lipid-protein interactions (PT, H, S) |
| Molecular (self-) assembly into supra-molecular structures: Kinetics and thermodynamics, Protein and lipid assembly, phyto-sterol assembly in oils (P. Venema, E. van der Linden) | Oil structuring in polyunsaturated fatty acids systems, high density protein particles, food grade nanoparticles for Pickering stabilisation, novel bio-amphiphiles (PT, H, S) |
METHODS
We use experimental, theoretical, and computer simulation methods, as given in the figure below.
CONTEXT
The world faces a considerable challenge in the next decades in providing tasty, healthy, and sustainably produced food in sufficient amounts. Relevant issues in this context are for example ingredient availability in relation to food properties like texture, taste, smell, colour, and nutritional and health impact. Another example is ingredient availability versus sustainability requirements during harvesting, processing, and storage. Finding practical solutions and innovations to these issues is key.
The issues are often interrelated. This implies that instead of considering each issue separate we need to consider the issues together (a system approach) in finding practical solutions and innovations. Since many of the issues relate to physical phenomena, macroscopic physical properties and physical environmental conditions, physics is a discipline that provides a framework that is common to many of the issues. This allows physics to contribute to a system approach, and thereby yield significant contributions in finding practical solutions and innovations.
Any macroscopic physical property of a material is determined by the properties of the constituent molecules, their mutual interactions, and its environmental conditions. Ultimately, we need to relate macroscopic properties to ingredient type and concentration, temperature and externally introduced fields, like for example flow fields. For our research the ingredients refer to water, proteins, polysaccharides, fats, oils, gasses, and minor components like vitamins and minerals. Relating the macroscopic to the molecular scale is scientifically challenging from a physics point of view. The large amount of information on a molecular scale needs to be reduced to a practically manageable amount for the macroscopic scale, without losing any information that is relevant. The first step is to consider a scale in between, the mesoscopic length scale. This, to a first approximation, is the scale above which the properties are not different from the properties of the entire (macroscopic) system, and below which only the molecular scale plays a role. This mesoscopic scale acts as a bridge between the macroscopic and molecular scale. For foods, the mesoscopic scale exhibits a rich variety in structures and properties, due the types of molecules and their weak interactions. The scale magnitude lies typically between a few nanometers and a few millimeters. Our focus is on this mesoscale in relation to the molecular and macroscopic scale. Understanding at this lengthscale implies better control of food properties enabling food innovations.
The scientific understanding of the mesoscale can be deepened by testing the validity of the acquired descriptions for other and/or new mesostructures. Such new mesostructures can be created by actively exploring the area of mesostructure design and development. At the same time, these new mesostructures lead to new food material properties and new foods, i.e. innovations. Therefore, mesostructure design and development is essential for deepening our physical understanding and for a bottom-up approach to arrive at new food materials, i.e. food innovations.
The interrelations between physics, (meso)structure design and development, and application driven research, allow integration to their mutual benefit, and this enables innovations in an effective way. Applying this integration delivers fundamental knowledge, new mesostructures, and application concepts for academic partners, industry and society.
METHODOLOGY
The integration of physics, mesostructure design and development, and application driven research is generally an iterative process. We may for example start with the development of a new mesostructure (a new type of fibril or protein microparticle), and subsequently investigate the fundamentals of its assembly, or the interactions between these structures. The fundamental knowledge this generates may either be used to create improved mesostructures, or to develop new applications (more stable emulsions or perhaps a meat substitute). In other projects we start with a specific application in mind, and then develop suitable mesostructures that optimize the properties of the new product. By studying the interactions between these novel structures, and between these structures and other ingredients in the product, we can efficiently select the type of mesostructure that provides optimal (macroscopic) properties of the product.
An example of this iterative approach is our work on protein fibrils. Twelve years ago we started working on fibril formation from food proteins, with the idea to use these fibrils for weight efficient ways of structuring aqueous phases. Fibrils can form transparent gels at relatively low concentrations, and can be used as thickening agents (functionalities the protein does not possess in its native state). With these applications in mind we started an exploration of the types of fibrils we could form from common food proteins, such as ß-lactoglobulin, α-lactalbumin, bovine serum albumin, ovalbumin, lysozyme, glycinin, conglycinin, and patatin, and studied the effect of pH, ionic strength, temperature, and flow conditions on fibril properties (mesostructure design and development). To better understand the differences in fibril properties, and their behaviour in applications, we embarked on a fundamental study of the self-assembly process of the fibrils, their phase behaviour, and their dynamic behaviour in flow fields. The fundamental insights in their behaviour has inspired new application areas for these fibrils, one of which is to reinforce microcapsules for encapsulation and controlled delivery of functional ingredients. Using knowledge on the properties of the fibrils (contour length, flexibility, charge, degree of branching) we constructed various types of microcapsules with a fibril reinforced nanocomposite shell, with a wide range in mechanical strength and permeability, which can be tailored to the specific needs of an application.