Electrospinning of PCL-Black Pepper Oleoresin Coatings

The PCL fibers containing black pepper oleoresin were directly electrospun onto both sides of the gelatin films using a high throughput electrospinning/electrospraying pilot line Fluidnatek^® LE 500 manufactured and commercialized by Bioinicia S.L. (Valencia, Spain). The solutions were electrospun under a constant flow using a 24 emitter multi nozzle injector that scans vertically onto the gelatin film (see Figure 1). A voltage of 20 kV, a flow-rate of 1.5 mL/h per single emitter, and a tip-to-collector distance of 18 cm was used. A PCL coating without black pepper oleoresin was used as control. The electrospun conditions were different for the latter materials including an applied voltage of 30 kV, a flow-rate of 1 mL/h per single emitter, and a tip-to-collector distance of 18 cm were used. To obtain transparent, adhesive, and continuous coating layers based on PCL, a curing heating step was applied. To do so, the multilayers were placed between hot plates without applying pressure at 70 °C for several seconds in order to obtain self-adhering ultrathin fibers coalescence and a continuous PCL coating. The various monolayer and multilayer structures developed in the study with the corresponding coding used throughout the paper are gathered in Table 1.