Encapsulation by electrospinning technique of carotenoid compounds from watermelon pulp with microemulsion method and optimization

In this study, first carotenoid components from watermelon pulp were extracted with surfactant-assisted extraction. Then, the extract was encapsulated into nanofibers by using electrospinning method in order to increase the strength of the extracts. The extraction and encapsulation conditions were optimized by creating mathematical models according to the response surface method. As a result, Extraction-1 and Extraction-2 conditions determined as two different surfactant-assisted extractions. These independent variables were investigated. Optimum conditions for the Extraction-1 and Extraction-2 were detected as 6.025 g/g S20/P (Span 20/Pulp), 8.827 of Gly/P (Glycerol/Pulp), 38.75 °C, 18.75 min, and 1.13 g/g, SMP/P(Sucrosemonopalmitate/Pulp), 7.53 g/g Salt/P, 66.25 °C, 46.3 min, respectively. The microemulsion obtained according to Extraction-1 conditions had the highest extraction efficiency (96.5%). The microemulsion in the most appropriate ratio was added to coating solutions and encapsulated by electrospinning. The zein solution provided the highest encapsulation efficiency (79.74%) and fiber in the desired structure. Optimum encapsulation conditions were determined as 23 kV, 1.7 mL/h and 12.76 cm. Finally, the storage stability of the obtained optimum nanofibers and the model foods including nanofibers were determined during 84 days. Except milk, the L *, a *, b *, C * and Hue values and carotenoid contents of the other samples decreased while the ΔE * values increased during storage. The highest carotenoid stability was in the nanofibers and then olive oil, milk and water samples including nanofibers.