Modification and Characterization of Waxy and Native Tapioca Starches for Stabilizing Resveratrol Pickering Emulsion

¹ Department of Industrial Chemistry, Faculty of Applied Science, King Mongkut’s University of Technology North Bangkok, 10800 Bangkok, Thailand
² Department of Chemical Engineering, Faculty of Engineering, Mahidol University, 73170 Nakhon Pathom, Thailand
³ Expert Centre of Innovative Herbal Products, Thailand Institute of Scientific and Technological Research, 12120 Pathum Thani, Thailand

^* Corresponding author: sukanya.t@sci.kmutnb.ac.th

Abstract

Tapioca starch is a promising biopolymer for use as a solid particle stabilizer in Pickering emulsions. This study aimed to enhance the emulsifying performance of native (NS) and waxy (WS) tapioca starches through antisolvent precipitation followed by esterification with 3% (w/v) octenyl succinic anhydride (OSA). Structural and functional changes were characterized by SEM, XRD, DSC, FTIR, contact angle measurements, and degree of substitution analysis. The modifications transformed the starch morphology from smooth granules into rough, aggregated particles and reduced crystallinity, gelatinization enthalpy, and the intensity of characteristic functional groups. Both starch types exhibited similar structural changes; however, the modified native starch (NSp-OSA) showed higher hydrophobicity (contact angle: 103.73 ± 0.50°) than the modified waxy starch (WSp-OSA, 84.83 ± 0.60°), resulting in improved emulsion stability. Emulsion screening using jojoba oil identified optimal starch-to-oil ratios of 2.0:1.2 g/g for NSp-OSA and 1.0:1.2 g/g for WSp-OSA. These conditions were then applied for encapsulating resveratrol (RES). Due to the poor solubility of RES in oil, a ternary solvent system comprising of PEG 400, jojoba oil, and olive oil (0.1:0.5:0.5:0.5 g/g) was formulated to enhance solubility and emulsion uniformity. The NSp-OSA formulation produced more stable RES-loaded emulsions than WSp-OSA. This study demonstrates the potential of modified tapioca starches as bio-based stabilizers for emulsion-based delivery systems.