Ultrasound-assisted starch succinylation (C8–C14): Balancing side-chain lengths and degree of substitution for optimal amphiphilicity and emulsification

In this study, rice starch was ultrasound-assisted (power = 0 W, 200 W, and 450 W) succinylated with C8–C14 anhydrides under controlled conditions, with the major aim of balancing side-chain lengths and degree of substitution (DS) for superior amphiphilicity and emulsification. A bell-shaped relationship between chain lengths and functionality was observed, peaking at decenyl succinic anhydride (DSA, C10)-modified starch, particularly DSA-450 W achieved optimal amphiphilicity (θ = 86.3°), emulsification performance (EAI = 34.3 m 2 /g, ζ-potential = −80.4 mV, CI > 61 % over 21 days), and a lower DS than OSA. Conventional octenyl succinic anhydride (OSA, C8) modification exhibited the highest swelling power (18.9 g/g) and peak viscosity (1348.5 BU). High-power ultrasound most enhanced tetradecenyl succinic anhydride (TDSA, C14) modification, yet the suboptimal contact angle and emulsification properties of TDSA-starch challenge conventional wisdom and show that longer hydrophobic side chains do not necessarily yield better performance. In summary, DSA-modified starch balances moderate hydrophobic chain lengths with reactivity and is expected to be an ideal alternative to OSA, offering a promising strategy for stabilizing Pickering emulsions with enhanced stability and cost-effectiveness in food and non-food applications.