Fabrication of pristine electrospun kafirin nanofiber mats loaded with thymol and carvacrol

In this project, we fabricated electrospun nanofiber mats from pristine kafirin, the storage protein of sorghum, for the first time which have the potential to be used as eco-friendly food packaging materials. The first novel step was kafirin extraction which showed that the purity of kafirin was higher in double-purification compared to single-purification, which led to high quality nanosized round, straight, unbroken and unentangled fibers. The electrospinning results indicate that binary solvent, 75% (v/v) acetic acid (AcOH) and 25% (v/v) butanol (BuOH) mixture, allows fabrication of homogenous nanofiber mats at 0.4 g/ml kafirin-to-solvent ratio, which is critical for to obtain good mechanical strength for the mats. Encapsulation of thymol and carvacrol was successful when the loading concentrations were 0.1 g/ml and 0.1–0.2 g/ml, for thymol and carvacrol, respectively. Loading of the fibers with the bioactives was confirmed with FTIR where the characteristic peaks for the bioactives appeared at 950 cm−1, 1150 cm−1, 1200 cm−1 and 1250 cm−1. Thymol or carvacrol encapsulation led to the conversion of some of the β-turn structures of kafirin into β-sheet structures. Surface hydrophilicity of loaded kafirin fiber mats decreased with increasing carvacrol concentration and increased with increasing thymol concentration.