Morphological, Structural, and Thermal Properties of Microbial Carotenoids Microencapsulated by Spray-Drying Using Different Combinations of Wall Materials

This study evaluated the spray-drying encapsulation of carotenoid-rich extracts produced by Sporidiobolus salmonicolor, with the optimization of a ternary wall system of gum arabic (GA), inulin (IN), and corn starch (ST). Carotenoids were produced in a semi-continuous bioreactor, extracted with organic solvents, and microencapsulated by spray drying. A 2³ CCRD was used to optimize the proportions of the wall materials. The microcapsules were subjected to physicochemical, morphological, structural, and thermal analyses. Optimal conditions (20% extract, 2% Tween 80, 5% wall material at a 1:1:1 ratio, 120°C inlet temperature, and 5.83 mL/min feed rate) achieved 75% EE, 20.5 µg/g carotenoid loading, 83% EY, 5.5% moisture, and 0.126 a_w. SEM showed spherical, smooth particles, while XRD indicated an amorphous structure stable up to 215°C. The optimized ternary system produced stable microcapsules suitable for use as sustainable natural colorants for food and pharmaceutical applications. PRACTICAL APPLICATIONS: The carotenoid microcapsules obtained from Sporidiobolus salmonicolor by spray drying using gum arabic, inulin, and starch show potential application as natural colorants and functional ingredients in food and pharmaceutical products. The observed technological properties, such as high encapsulation efficiency, low moisture content and water activity, an amorphous structure, and thermal stability, favor handling, stability, and incorporation into different matrices, including beverages, dairy products, and powdered foods. The developed system represents a sustainable alternative to synthetic pigments and a promising platform for the industrial utilization of microbial carotenoids.