Encapsulation efficiency and thermal stability of norbixin microencapsulated by spray-drying using different combinations of wall materials

Abstract

Norbixin is a carotenoid with antioxidant properties. It is commonly used as a natural coloring in processed products; however, its chemical structure makes it susceptible to environmental factors such as light, oxygen, and temperature. The microencapsulation technique is used to improve the stability and solubility of the compound. The process efficiency depends on the encapsulation agents and operational parameters. In this study, Gum Arabic (GA) and Maltodextrin (MD) were used in different proportions as wall materials. All formulations were prepared with the same ratio between the core and wall material. The formulation 0:100 (MD:GA) showed the highest microencapsulation efficiency with 40% of total soluble solids (TSS) (74.91%–226.40μg/g) and a good process yield (61.07%). The norbixin microcapsules (MCNs) showed a uniform particle diameter, good homogeneity, high solubility (>90%), low moisture (2.86±0.81%) content and antioxidant activity (77.77±0.59μmol TE/g dry sample). The study of stability was carried out in the aqueous model system at temperatures of 60, 90 and 98°C for 300min. Thermal degradation kinetics followed a first order kinetic reaction. The activation energy (Ea) required for degradation of MCN (Ea=15.08kcal/mol) was twice as high as that required for norbixin non-encapsulated (Ea=7.61kcal/mol). The microencapsulation by spray-drying improved a thermal stability of norbixin. Therefore increases in the shelf life of this bioactive compound and MCNs can be considered as an additive with high potential for use as a natural coloring in foods and beverages.