Protein aggregates as building blocks for oil structuring

E. Scholten
Wageningen University,
Netherlands

Keywords: food materials, oleogels

Summary:

Over the recent years, structuring of organic solvents and oils into organogels (oleogels) has gained much attention from colloid, material and food scientists. Organogels are obtained through network formation of certain gelators (organogelators), and are often classified into two different categories: (i) low molecular weight organogelators (LMOG), that self-assemble into larger interconnecting structures as cylindrical micelles or bilayers, or (ii) polymeric organogelators, of which polymers and polysaccharides have been shown to provide a network through entanglement formation. Although many gelators are known, their use in applications is limited as the gelators are often expensive, not effective, and have low stability. Especially in the food and pharmaceutical industry, the need for such new gelators is required. In this presentation, a new category to the common oleogelators will be presented: proteins. As they are cheap, widely available, biocompatible and food grade, they have a large potential to be used in many different types of applications, especially in the food and pharmaceutical industry. To obtain such gels, heat-set protein building blocks of different dimensions (200 nm, a few mm) were created, which are used to create a network in oil to form so-called protein oleogels. A method was developed to transform the protein building blocks from an hydrophilic aqueous phase into hydrophobic oil using a solvent exchange technique. This method is used to obtain either firm gels with brittle fracture properties, or soft gel with plastic deformation and yielding behavior. By changing the interactions between the building blocks in the network formation, the final properties of the protein oleogels can be controlled. This presentation will give an overview of the different interactions that are of relevance between proteins in hydrophobic environments, and discuss how these interactions can be varied. The effect of attractive interactions in the network, such as hydrogen bonds, capillary interactions, and van der Waals interactions will be discussed, as well as the effect of repulsive hydrophobic interactions. The oleogels show large versatility regarding rheological properties (strength, yield stress and plastic behavior), in a similar way as is known for very common protein hydrogels. This presentation will briefly discuss how these new type of oleogels can be used in commercial applications, and how they could be produced on large scales.