Development and Structural Characterization of Pullulan/Lecithin/Zein Composite Nanofibers Loaded with Mountain Germander (Teucrium montanum) Polyphenolic Extract

In this study, the electrospinning technique was employed to encapsulate mountain germander (MG) polyphenolic extract into pullulan/zein (PUL:ZE) delivery systems stabilized with sunflower lecithin. The rheological and physical properties of the pullulan (PUL), PUL:ZE, and zein (ZE) polymer solutions were evaluated to assess their electrospinnability potential. Fabricated nanofibers were then characterized for their morphology, physicochemical, and thermal properties, as well as encapsulation efficiency and simulated in vitro digestion. The elastic component of the polymer solution, quantified by the Deborah number, showed a strong correlation with nanofiber diameter (r = 0.75). FT-IR spectra confirmed the role of sunflower lecithin as a mediator in the formation of hydrogen and hydrophobic interactions among PUL, ZE, and polyphenols. The circular dichroism spectra confirmed the influence of the MG extract on the change in the secondary conformation of the protein structure. The PUL:ZE delivery matrix proved to be suitable for the retention of phenylethanoid glycosides (encapsulation efficiency > 73%). The formulation 50PUL:50ZE was found to have the highest potential for prolonged release of polyphenols under gastrointestinal in vitro conditions. These findings propose a water-based electrospinning approach for designing polyphenolic delivery systems stabilized with lecithin for potential applications in active food packaging or nutraceutical products.