Investigating the stability of plant-based emulsions: Towards high quality 3D-printed meat analogues

Over the last decade, research on 3D food printing (3DFP) as novel processing technology for meat analogues has emerged. This combines bioscience and chemical engineering to understand every aspect of the process. Protein-rich and lipid-rich inks are applied, where the animal fat may be mimicked by an emulsion, i.e. a mixture of two immiscible liquids. Despite the plant-based trend, stabilizing multiphasic food products with plant-based proteins as stabilizers instead of conventional animal proteins still faces some challenges. The main reason is that plant proteins perform differently at the interface as they exhibit lower aqueous solubility and thus form weaker viscoelastic films. Therefore, the formulation and long-term stability of plant-based emulsions need further investigation. Preferably, one can find a way to predict the long-term emulsion stability. This work aims at (i) understanding the stabilization of oil-in-water (O/W) emulsions with plant-based proteins, (ii) extracting interfacial and bulk rheological data to enhance the rheological comprehension of O/W emulsions, and (iii) relating the stability to the used methods. O/W emulsions with oil/water content of 80/20 were formulated. The oil phase consists of soybean oil, whereas the water phase concerns a soy protein isolate (SPI) dispersion. Two different treatments were performed on the SPI dispersions. Whereas interfacial tension, interfacial rheology, and bulk rheology were investigated. Only the interfacial rheological results could explain the difference in emulsion stability after 30 days. In summary, this work provides a relation between the interfacial properties and long-term stability of plant-based emulsions. The reported findings acknowledge the importance of rheology and can pave the way to include novel lipid-rich inks in 3D-printed plant-based meat.