Production of core-shell nanofibers from zein and tragacanth for encapsulation of saffron extract.

In this study, encapsulation of aqueous saffron extract (ASE) was studied using a core-shell nanofiber structure (zein-tragacanth) via coaxial electrospinning technique. Morphological features of nanofibers were investigated under different processing conditions (polymer concentration and applied voltage). The nanofibers produced under optimum criteria had diameter in a range of 95 to 271 nm. Concentration of zein and percentage of ASE were found to be critical factors affecting loading capacity (LC) and encapsulation efficiency (EE). The range of LC and EE were 3.57-9.52% and 60.89-91.55%, respectively. FTIR and differential scanning calorimetry (DSC) characterizations demonstrated that ASE was appropriately encapsulated in the nanofibers matrix with high thermal stability. TEM images showed a core-shell structure. Release values of 21.66, 27.75, 43.88 and 16.12% of saffron extract were observed in saliva, hot water, gastric and intestinal media, respectively. Mechanism of safranal release from fibers for saliva, water, gastric and intestinal were well demonstrated by Kopcha, Peppas-Sahlin, Peppas-Sahlin and Ritger-Peppas models, respectively. Finally, the results of this research indicated that produced thermostable core-shell nanofibers can be used in various food industries such as chewing gum and tea bag development.