Emulsion-based oleogelation using octenyl succinic anhydride modified granular cold-water swelling starch
Ornicha Champrasert, Leonard M.C. Sagis, Prisana Suwannaporn
Abstract
Oleogels were produced starting from Pickering emulsions, stabilized by octenyl succinic anhydride (OSA) modified high amylose (HS-OSA), waxy (WS-OSA), and granular cold-water swelling starch (GCWS-OSA). GCWS-OSA had the highest degree of OSA substitution (DS) and contact angle with the oil-water interface, and the smallest emulsion droplet size (0.0149, 80.4°, 12.58 μm), followed by WS-OSA (0.0098, 76.2°, 22.83 μm) and HS-OSA (0.0049, 73.3°, 31.50 μm). In small amplitude oscillatory shear (SAOS), all template emulsions and oleogels had G’ > G’’ (tan δ ≤ 0.1) and behaved as soft viscoelastic solids. The highest G’ was observed for WS-OSA and GCWS-OSA, which clearly produced a much stiffer material. In large amplitude oscillatory shear (LAOS), WS-OSA and GCWS-OSA oleogels showed a progressive disruption of the microstructure, which resulted in an increase in viscous dissipation. At the highest strain of 20.5%, WS-OSA and GCWS-OSA were showing completely plastic behavior, whereas the structure of the HS-OSA based oleogel still displayed significant residual elasticity, indicating only partial disruption of the microstructure. WS-OSA and GCWS-OSA also had a much higher strain overshoot (Payne effect) in G”, then the sample based on HS-OSA. The higher DS and granular structure of GCWS-OSA contributed to a more stable Pickering emulsion and stiffer oleogel.