Protein-specific behaviour in food products; aggregation, network assembly and responses to mechanical deformation / Dynamic energy dissipation in protein-networks determines the texture of food gels

1st Talk (Harmen de Jongh) ---

In food products proteins are not only a macronutritional irreplaceable component, but also as structuring agent every protein type will create its own specific textural space. As in future animal proteins will become scarce, there is an increasing demand to better understand how proteins from plant sources generate microstructural building blocks, assemble into spatial networks during gel formation and how mechanical deformation leads to breakdown of these food gels in relation to mouthfeel. In this presentation an overview will be presented on the specifics of protein denaturation, aggregation and gel formation and how different gel structures can be generated and controlled at length scales ranging from nanometer up to supra-micron dimensions. The consequences of the different gel morphologies for a number of relevant functional characteristics will be discussed.

2nd Talk (Saskia de Jong) ---

During oral processing of semi-solid (protein-based) food products the balance how the applied energy dissipates into the protein-network has been shown to be critical for texture perception. The lack of a consistent description of this balance makes it difficult to, for example, employ proteins from different sources or design alternative processing routes in product (re-) formulation for the food industry.

Dissipation of energy applied to a protein continuous network may occur via a number of mechanisms, like (micro)fracture, structural relaxation, friction caused by flow of entrapped serum or between microstructural elements, or by irreversible mechanical deformation of the material. Each of these contributions will reduce the stored (recoverable) energy and may be time- and strain-dependent. In this presentation the protein-specific impact on the recoverable energy (RE) by stress dissipation via relaxation of (micro)structural rearrangements within protein gels is illustrated. Two protein-based gels are presented for their response to time-dependent mechanical deformation: one derived from cow’s milk caseinate and the other prepared from pork skin gelatin. These gels are known to develop structurally distinct network morphologies and the potentials for processing routes to direct the energy balance for designed texture are discussed.