Extrinsic factors influencing nano-/micro-particle formation in pure soy glycinin solution via heating

Abstract

Soy glycinin could self-assemble into nanoparticles, microgels or hollow microcapsules depending on the extrinsic conditions. This research compares ion- and/or pH-induced particle formation through simple heat treatment of soy glycinin (80 °C, 5 min and 600 r/min), and the difference of zeta potential, particle size, hydrophobicity and their relevance to particle morphology were investigated. The results showed that only a combination of monovalent cation (K+ or Na+) and monovalent anion (Cl−) promoted the formation of hollow microcapsules with coexistence of microgels (protein solution pH: 7.2), whereas a reduce in pH inhibited hollow microcapsule formation upon heating, either in the presence of electrolytes or not. Strategies for size reduction of microparticles were also studied, either by increasing the shear stress during heating or through ultrasound pre-treatment of soy glycinin. In general, native soy glycinin was favorable for the formation of hollow microcapsules than the partially denatured, and the hollow microcapsule formation was highly sensitive to the extrinsic conditions.