Protein aggregation and gelation are highly sensitive to ionic environments and external physical processing conditions. This study investigated how Hofmeister anions (SO42−, Cl−, NO3−) direct the fabrication and properties of soy protein isolate (SPI) hydrogels formed under a low-voltage direct current (DC) electric field. Anion type governed protein pre-aggregation, with SO42− most effectively enhancing the modulus and viscosity of SPI aggregates, resulting in the highest gel fraction. The hydrogel network was predominantly stabilized by disulfide bonds and hydrophobic interactions, depending on the specific Hofmeister anion employed. Increasing salt concentration (100–300 mmol/L) reinforced these molecular interactions and led to microstructural coarsening. The electric field-induced anisotropic structure was maintained in hydrogels containing chaotropic-to-intermediate anions (Cl− and NO3−), whereas the strongly kosmotropic SO42− at 300 mmol/L disrupted this ordered architecture, suggesting that excessive protein aggregation prior to electrogelation inhibits directional ordering. Although all hydrogels exhibited high water content (85–90
Growing concerns regarding food safety, environmental sustainability, and the limited availability of synthetic packaging materials have driven demand for biodegradable and multifunctional alternatives. Starch-based films containing curcumin represent a multifunctional packaging system for active and smart food packaging, by combining curcumin’s pH-responsive, antioxidant, and antimicrobial properties with the film-forming ability of starch. This review critically examines the potential of curcumin-containing starch films in food packaging by discussing the functions of curcumin, the characteristics of the starch matrix, fabrication methods, and current strategies to enhance performance, including nanoencapsulation, ternary complexes, and scalable processing routes. As an active packaging component, curcumin provides photodynamic antioxidant and antimicrobial functions that have been proven to extend food shelf life. As a smart indicator, its reversible color changes across a pH range of 3–11 enables real-time visual monitoring of food spoilage. However, curcumin’s hydrophobic nature limits its dispersion and stability retention in hydrophilic starch matrices, and no single formulation approach has yet simultaneously optimized all performance dimensions. Commercialization is further hindered by the absence of standardized release kinetics testing protocols, limited pilot-scale validation, and unresolved regulatory pathways governing curcumin migration limits in food contact applications. Emerging approaches including co-encapsulation, starch structural modification, and green solvent-assisted processing are discussed as feasible directions for overcoming these barriers. This review provides an integrated technical framework and a prioritized research roadmap to guide the rational design and scale-up of curcumin–starch film systems for next-generation sustainable food packaging.
