Phase separation in food material design inspired by Nature

The Effects of Oil Extraction Methods on Recovery Yield and Emulsifying Properties of Proteins from Rapeseed Meal and Press Cake

The agricultural sector is thought to be responsible for around 30% of the anthropogenic climate change and it is well established that high meat consumption has a tremendous impact on the environment. Rapeseed is mainly used for production of vegetable oil, but press cake has high protein content with the potential for incorporation into new plant protein-based foods. Protein was recovered from press cakes generated from different oil pressing processes. Industrially cold-pressed, hot-pressed, and solvent-extracted rapeseed press cake and the effect of heat treatment in the recovery process was assessed. Protein recovery yield, protein concentration and emulsifying properties were analyzed. Cold-pressed rapeseed press cake (RPC) recovered in the absence of heat, yielded the highest protein recovery (45%) followed by hot-pressed rapeseed meal (RM) (26%) and solvent-extracted RM (5%). Exposure to heat during recovery significantly reduced the yield for cold-pressed RPC but no difference was found for hot-pressed RM. The protein recovery yield was improved for solvent-extracted RM when heat was applied in the recovery process. The ability to stabilize emulsions was highest for protein recovered from cold-pressed RPC, followed by hot-pressed RM and solvent-extracted RM, and was in the same range as commercial emulsifying agents. Heat treatment during recovery significantly reduced the emulsifying properties for all pressing methods examined. This study suggests that cold-pressed rapeseed press cake without heat in the recovery process could be a successful strategy for an efficient recovery of rapeseed protein with good emulsifying properties.

Use of molecular interactions and mesoscopic scale transitions to modulate protein-polysaccharide structures

Mixed protein-polysaccharide structures have found widespread applications in various fields, such as in foods, pharmaceuticals or personal care products. A better understanding and a more precise control over the molecular interactions between the two types of macromolecules leading to an engineering of nanoscale and colloidal building blocks have fueled the design of novel structures with improved functional properties. However, these building blocks often do not constitute the final matrix. Rather, further process operations are used to transform the initially formed structural entities into bulk matrices. Systematic knowledge on the relation between molecular structure design and subsequent mesoscopic scale transitions induced by processing is scarce. This article aims at establishing a connection between these two approaches. Therefore, it reviews not only studies on the underlying molecular interaction phenomena leading to either a segregative or associative phase behavior and nanoscale or colloidal structures, but also looks at the less systematically studied approach of using macroscopic processing operations such as shearing, heating, crosslinking, and concentrating/drying to transform the initially generated structures into bulk matrices. Thereby, a more comprehensive look is taken at the relationship between different influencing factors, namely solvent conditions (i.e. pH, ionic strength), biopolymer characteristics (i.e. type, charge density, mixing ratio, biopolymer concentration), and processing parameters (i.e. temperature, mechanical stresses, pressure) to generate bulk protein-polysaccharide matrices with different morphological features. The need for a combinatorial approach is then demonstrated by reviewing in detail current mixed protein-polysaccharide applications that increasingly make use of this. In the process, open scientific questions that will need to be addressed in the future are highlighted.

Gelatin-polysaccharide composite scaffolds for 3D cell culture and tissue engineering: Towards natural therapeutics

Gelatin is a promising material as scaffold with therapeutic and regenerative characteristics due to its chemical similarities to the extracellular matrix (ECM) in the native tissues, biocompatibility, biodegradability, low antigenicity, cost-effectiveness, abundance, and accessible functional groups that allow facile chemical modifications with other biomaterials or biomolecules. Despite the advantages of gelatin, poor mechanical properties, sensitivity to enzymatic degradation, high viscosity, and reduced solubility in concentrated aqueous media have limited its applications and encouraged the development of gelatin-based composite hydrogels. The drawbacks of gelatin may be surmounted by synergistically combining it with a wide range of polysaccharides. The addition of polysaccharides to gelatin is advantageous in mimicking the ECM, which largely contains proteoglycans or glycoproteins. Moreover, gelatin-polysaccharide biomaterials benefit from mechanical resilience, high stability, low thermal expansion, improved hydrophilicity, biocompatibility, antimicrobial and anti-inflammatory properties, and wound healing potential. Here, we discuss how combining gelatin and polysaccharides provides a promising approach for developing superior therapeutic biomaterials. We review gelatin-polysaccharides scaffolds and their applications in cell culture and tissue engineering, providing an outlook for the future of this family of biomaterials as advanced natural therapeutics.