Sustainable Microencapsulation of Limonene via Complex Coacervation with Natural Biopolymers

Essential oils have been extensively explored across different industrial sectors due to their multiple bioactive properties and health benefits. Among their main constituents, terpenes stand out, with limonene being one of the most abundant in nature, particularly present in citrus essential oils. This compound possesses well-recognized antioxidant, antimicrobial, aromatic, and therapeutic activities, making it a promising candidate for applications in pharmaceuticals, cosmetics, food products, and sustainable materials. However, its high volatility and sensitivity to adverse environmental conditions limit its stability and direct application, making microencapsulation an essential strategy for preserving its functional properties and enabling controlled release. Therefore, the aim of this study was to produce limonene microcapsules via complex coacervation using natural biopolymers, such as chitosan and gum arabic, in order to investigate the effect of biopolymer concentration and limonene content on productivity as well as on the chemical and morphological properties of the particles. The microcapsules were characterized in terms of morphology, solid content, particle size, and encapsulation efficiency. Microscopic analyses revealed predominantly spherical and uniform morphologies, with diameters ranging from 1 to 10 µm. The solid content varied from 2.06% to 5.68% (w/w), influenced by formulation composition and close to the theoretical values calculated. Particle size distribution by laser diffraction showed mean values between 0.74 µm and 1.22 µm. Encapsulation efficiencies were remarkably high, exceeding 99% in all trials. The results confirm the feasibility of complex coacervation with natural biopolymers as a sustainable, versatile, and highly efficient method for limonene microencapsulation. This approach not only ensures the protection and stability of the compound but also enables its incorporation into innovative formulations, driving the development of functional products with high added value across different industrial sectors.