Influence of protein content on plant-based emulsified and crosslinked fat crystal networks to mimic animal fat tissue

Abstract

Plant-derived fats differ from animal fat tissue insofar that they do not exhibit elastic properties, but rather show a plastic behaviour upon deformation. To mimic this key property of animal fat, a system using emulsified plant derived fat crystal networks (EFCNs) embedded as droplets inside a plant protein matrix has recently been introduced. In this study the effect of protein content on the properties of the mixed network system was investigated. EFCNs were produced by hot-emulsifying mixtures of canola oil and fully hydrogenated canola oil (solid fat) at 65 °C using protein dispersions containing 5 and 11 wt% soy protein isolate (SPI). Gelation was induced by addition of transglutaminase at 37 °C, forming a covalently-linked protein network. Confocal laser scanning microscopy images revealed a decrease in mean droplet diameter at higher protein concentration. Increasing protein content, increased hardness, but also counteracted the increasingly dominating plastic behaviour at higher solid fat contents, originating from the network of fat crystals within the lipid phase. Samples manufactured with 11% SPI dispersions had higher values for cohesiveness and springiness than samples containing 5% SPI. Rheological analysis similarly showed that the limit of the linear viscoelastic region γL was found to occur at larger strains in samples with higher protein content. Taken together, results indicate that the material behaviour at a desired solid fat concentration can be tuned by variation of the protein content, which gives flexibility to manufacturers of products using the new fat system to adjust to changing processing or product requirements.