Dados do Trabalho

Título

ENCAPSULATION OF BETANIN-RICH EXTRACT IN ULTRA FINE ZEIN FIBERS BY ELECTROSPINNING TECHNIQUE: TECHNOLOGICAL OPTION FOR THERMAL STABILITY OF PIGMENTS

Introdução

Betanin can be used to color different products, but it has low stability against temperature. Therefore, this study aimed to encapsulate betanins extracted from pitaya pulp in ultrafine zein fibers by the electrospinning technique and evaluate their thermal stability.

Material e Métodos

Pitaya pulp was sonicated for 30 min at 50 °C using distilled water (pH 5.5) to obtain a betanin-rich extract (BE). Subsequently, zein solutions were obtained by solubilizing them in 70% ethanol and adding lyophilized BE (5, 10, 15, 20, 25, 30, and 35%) to be subjected to the electrospinning technique. The materials obtained were evaluated for morphology and average diameters by scanning electron microscopy, loading efficiency by spectrophotometry, thermal properties by thermogravimetry, and color by a colorimeter. The results were evaluated using ANOVA and Duncan's test.

Resultados e Discussão

The fibers presented cylindrical and homogeneous morphology with average diameters ranging from 335-515 nm in concentrations of 0 to 35% of BE, being characterized as ultrafine fibers. The materials presented loading efficiency ranging from 49 to 65%, with a significant difference (p≤0.05) between some concentrations, with the ultrafine fibers
with 30% of BE having the highest loading efficiency (65.04 ± 1.53%). The thermograms indicate that the ultrafine zein fibers protected the BE at concentrations of 5 and 20%, with thermal degradation events characteristic of the pure extract at concentrations of 25 and 35% of BE in the materials. The thermal events for concentrations ranging from 5 to
20% started between 183 and 186 °C, with a maximum temperature of the event ranging from 190 to 196 °C, being characteristic of the degradation of the molecular structure of betanin. The ∆E* showed a significant difference (p≤0.05) among all BE concentrations in the materials. Values of ∆E* > 3.50 for 25% of BE in the ultrafine fibers were obtained, corroborated with the findings of the thermogravimetric analysis. Ultrafine zein fibers were obtained, with a maximum loading efficiency of 65% for fibers with 30% BE.

Conclusão

The materials were efficient in protecting the extract up to a concentration of 20%, with degradation at later concentrations, but associated with extract adhesion on the external region of the materials.