Rutin loaded zein-glycyrrhizin acid nanocomplexes: construction, characterization and potential application in yogurt

Abstract This study prepared ternary glycyrrhizic acid/rutin/zein (GRZ) complexes (at a zein: GA mass ratio of 1:1) via anti-solvent precipitation at varying pH levels (3.5, 4.5, 6.0). The pH 6.0 complex demonstrated optimal characteristics, featuring the smallest particle size (112 nm) and highest absolute zeta potential (−35.4 mV). Superior rutin encapsulation efficiency was achieved for complexes formed at pH 4.5 and 6.0. All complexes exhibited high physical stability across a pH range of 6.0–8.0, at temperatures up to 85 °C, and in salt concentrations up to 15 mmol/L. Complexes formed at pH 4.5 and 6.0 maintained better re-dispersibility after freeze-drying. FTIR and XRD analyses confirmed the formation of hydrogen bonds and hydrophobic interactions, resulting in an amorphous structure. Notably, GRZ complex incorporation enhanced yogurt coagulation without affecting fermentation kinetics. These findings establish a promising strategy for developing efficient rutin delivery systems with potential for functional food applications.