Anais do Simpósio Latino Americano de Ciências de Alimentos
Actas del 14 SLACA - Simposio Latinoamericano de Ciencia de los Alimentos

Onion skin (Allium Cepa, L.) is usually discarded by industries, but this residue is an alternative source of bioactive compounds, especially phenolics. However, these compounds can be encapsulated in materials, as starch, in order to preserve structural integrity, preventing their bioactivity losses. Electrospinning is an effective encapsulation technique that stands out for not involving high temperatures or pressures. In the literature, no studies have been found regarding the use of white sweet potato starch for encapsulation of onion skin bioactive extract by electrospinning. Therefore, the aim of this study was to encapsulate red onion skin extract (ROSE) in native sweet potato starch nanofibers by electrospinning. The ROSE was extracted using 70% ethanol (v/v, in deionized water) at a ratio of 1:45 (w/v). Then, it was lyophilized and stored at -20°C. The fiber-forming polymer solution was prepared by dissolving 0.6 g of starch in 3 mL of 75% formic acid (v/v, in deionized water) keeping under agitation for 20 h. The parameters used in the electrospinning process were: voltage of 18kV, flow of 0.75 mL/h, and needle-collector distance of 20 cm. The ROSE was incorporated into the solutions at concentrations of 0, 3, 6, and 9% (w/w). The nanofibers were evaluated for their morphology through scanning electron microscopy, diameter distribution by measuring 100 random fibers and antioxidant activity by DPPH (2,2-diphenyl-1-picrylhydrazyl) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods. The fibers showed nanometric scale, with uniform and continuous morphology, without the presence of beads. The average diameter varied from 137 to 217 nm, decreasing gradually with the incorporation of ROSE. For antioxidant, it ranged from 27.4 to 44.5% for DPPH and from 34.8 to 92.1% for ABTS, increasing according to the incorporation of ROSE. The starch bioactive nanofibers have great potential for application in active packaging, as well as directly into food products matrix.