Comparative Evaluation of Conventional and Innovative Wall Materials for Microencapsulation of Helichrysum splendidum Essential Oil

The encapsulation of essential oil (EO) from indigenous plants presents a promising strategy to improve its stability, controlled release, functional efficacy, and application in food systems. This study compared the effectiveness of four conventional wall materials (gum Arabic, GA; whey protein concentrate, WPC; sodium alginate, SA and chitosan) and two novel wall materials (Opuntia ficus-indica, L. cladodes mucilage and waste), in encapsulating EO from Helichrysum splendidum, a South African indigenous plant using the freeze-drying technique. The resulting powders were characterized based on their physical, technofunctional, chemical, and biological properties. The results revealed significant variations across the wall materials. Mucilage showed the highest encapsulation efficiency (62.54%) and favorable packing properties (highest bulk and tapped densities), WPC has the smallest particle size (0.22 µm) and PDI (0.23), superior DPPH radical scavenging activity (IC₅₀ = 3.6 mg/mL), good thermal stability (maximum degradation at 305 °C), and the highest cumulative in vitro EO release (65.60%), while chitosan exhibited the strongest antifungal activity (LD₁₀₀ = 1.25 mg/mL). Structural analysis using SEM, XRD, and FTIR confirmed successful encapsulation and revealed differences in morphology, crystallinity, and functional group interactions, while the in vitro release of EO from the wall materials was successfully modelled. The principal component analysis (PCA) revealed that no single wall material exhibited uniformly superior characteristics across all parameters suggesting that synergistic combinations of WPC and chitosan may enhance the microencapsulation of H. splendidum EO and its application in active food packaging.