Pectin-chitosan multilayer films for controlled anthocyanin release: Experimental structure-property relationships...

Layer-by-layer (LbL) assembly of biological macromolecules has been widely employed to fabricate polymer films for the controlled release of bioactive compounds. Numerous studies have shown that properties such as nano- and microstructure, swelling behavior, and mechanical performance can influence the functionality of these biopolymer films. Because the preparation of LbL films involves many intertwined experimental variables, it becomes challenging to establish a direct correlation between the film architecture and its functional properties. In this work, principal component analysis (PCA) was used as a complementary exploratory tool to integrate mechanical, structural, antioxidant, and release-related parameters in a series of polysaccharide/protein LbL films encapsulating anthocyanins. Dual controlled-release multilayers were produced by incorporating zein-anthocyanin coacervate complexes into spray-assisted LbL architectures composed of alginate, pectin, zein, and chitosan. Among the evaluated systems, pectin-chitosan films containing zein-anthocyanin (P/Ch/A) exhibited the highest encapsulation efficiency (77%), limited swelling over a wide pH range, and superior stiffness and tensile strength, together with high extensibility, compared to zein-containing films. The multivariate analysis was consistent with the direct experimental results and highlighted formulation-dependent clustering, with P/Ch/A showing the most balanced overall property profile for polyphenol delivery.