Amyloid-like sodium caseinate/pectin assemblies as multi-interface building blocks for wax-adhesive, transport-regulated active fruit coatings

AH-SC/P served as a multi-interface building block for active fruit coatings. • Acid–heat restructuring improved fruit-wax adhesion nearly five-fold. • Pectin regulated colloidal phase behavior and processable viscoelastic networks. • AH-SC/P stabilized 3% EUG with 94.95% encapsulation efficiency. • AH-SC-P-E delayed fruit deterioration with preliminary 28 d compatibility. Poor wetting and weak retention on low-energy waxy fruit surfaces remain major engineering barriers for waterborne edible coatings, even when the coating matrix shows good barrier or antimicrobial activity in model systems. Here, we developed a multi-interface engineering strategy to construct transport-regulated active coatings by restructuring sodium caseinate (SC) into wax-affinitive amyloid-like assemblies and regulating the resulting assemblies with pectin (PEC). Citric acid-assisted heating produced β-sheet-rich acid-heat-treated SC (AH-SC) assemblies with exposed hydrophobic domains, supporting stronger adsorption on a representative fruit-wax model and increasing the 180° peel force nearly fivefold from 65.3 to 323.2 N/m. PEC acted as a charged hydrocolloid regulator, balancing the wax affinity of AH-SC with colloidal phase control, shear-thinning processability, weak viscoelastic network formation, and oil–water interfacial adsorption. The optimized 2:1 AH-SC/P ratio stabilized 3% eugenol (EUG) with 94.95% encapsulation efficiency, enabled two-stage EUG release, and sustained antimicrobial and antioxidant activity. Upon drying, the emulsion was converted into a flexible, water-resistant, visually compatible, and water-removable coating matrix. Application tests on kumquats and strawberries showed reduced water loss, maintained firmness, delayed quality deterioration, and suppressed microbial growth. A 28-day mouse oral gavage study showed no obvious systemic or histological abnormalities under the tested conditions, supporting preliminary in vivo compatibility. Overall, this work establishes AH-SC-PEC as a single food-compatible hydrocolloid building block for coordinating oil–water stabilization, coating-matrix formation, fruit-wax adhesion, active-compound transport, and post-use removability. Download: Download high-res image (412KB) Download: Download full-size image