Characterization, microstructure, and spectroscopic study of optimized sodium caseinate-sorbitol active biofilms with citral microencapsulate

There is increasing interest in the development of biodegradable active packaging, as well as in the wide availability of resources and methods for its production. This study aimed to formulate and characterize biofilms with sodium caseinate (SC) and sorbitol (Sb), incorporating citral microparticles (CM) as antimicrobial. The active biofilms were prepared by the casting method and optimized by response surface methodology, minimizing transparency, opacity, and elastic modulus concerning the SC:Sb (between 1:0.5 and 1:1.5) and SC:CM (between 1:0.5 and 1:1.5) ratios. The thickness, color, mechanical, and microstructural properties of the biofilms made with the optimal conditions (the SC:Sb and SC:CM ratios of 1:0.91 and 1:0.95, respectively) were then characterized. In addition, Fourier transformed infrared (FT-IR) and mid-infrared (MID) spectroscopy were performed for qualitative purposes to assess the molecular interactions in the supplies and mixtures used in the formulation of the active biofilms. The optical, physical, and mechanical properties were experimentally evaluated at this optimum point. The FT-IR data indicate intermolecular interactions between the biofilm components. The active biofilms obtained under optimal conditions show a thickness of 150.0 mu m, with acceptable optical and mechanical properties. The active biofilm obtained may be a promising material for the packaging of perishable fresh foods.