Tunable oleosome-based oleogels: Influence of polysaccharide type for polymer bridging-based structuring

Abstract

This research proposes a gelation method using soybean oleosomes as templates in combination with polysaccharides. Two anionic polysaccharides, sodium alginate, and xanthan gum were investigated for their ability to induce bridging flocculation. Bridging flocculation occurs when flexible polysaccharides such as alginate strongly interact with oppositely charged oleosome particles in acidic pH ranges. In contrast, the more rigid xanthan leads to a different flocculation mechanism, which is not driven by strong electrostatic attractive interactions. In microscopy images, xanthan induced microscopic and macroscopic phase separation between oleosome droplets and xanthan, presenting large, irregular-shaped particles. The ratio between alginate chains and oleosome droplets is critical for optimum bridging, where 0.005 g/g (also expressed as an equivalent per droplet surface area 0.4 mg/m2) induced extensive droplet flocculation. It is possible to obtain an interconnected droplet network at this optimum ratio. Upon densification at the optimum ratio, a compact and self-supporting gel of about 46 wt% starting from 5 wt% oleosome is obtained. Oscillatory rheology showed that gels at optimum bridging ratio have higher moduli (G’) than those formed at a different ratio, confirming a highly cross-linked network. Bridging flocculation provides an alternative method to design gels with predictable rheological properties suitable for food and drug design and cosmetic applications.